<Page>
    AS FILED WITH THE U.S. SECURITIES AND EXCHANGE COMMISSION ON MAY 7, 2002
                                                     REGISTRATION NO. 333-
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------

                       SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, DC 20549


                                AMENDMENT NO. 1
                                       TO
                                   FORM F-10
                          REGISTRATION STATEMENT UNDER
                           THE SECURITIES ACT OF 1933


                             TRANSALTA CORPORATION
             (Exact Name of Registrant as Specified in Its Charter)

<Table>
                                                        
            CANADA                     NOT APPLICABLE           NOT APPLICABLE
      (Province or Other             (Primary Standard         (I.R.S. Employer
Jurisdiction of Incorporation    Industrial Classification    Identification No.
       or Organization)         Code Number (if Applicable))   (if Applicable))
</Table>

    110 - 12TH AVENUE S.W., CALGARY, ALBERTA, CANADA T2P 2M1  (403) 267-7110
   (Address and Telephone Number of Registrant's Principal Executive Offices)

       CT CORPORATION SYSTEM, 111 EIGHTH AVENUE, 13TH FLOOR, NEW YORK, NY
                             10011  (212) 894-8700
            (Name, Address (Including Zip Code) and Telephone Number
        (Including Area Code) of Agent For Service in the United States)

                                   COPIES TO:

<Table>
                                                            
       RODGER D. CONNER                 BRUCE L. MACPHAIL                ROBERT A. ZUCCARO
     TransAlta Corporation           McCarthy Tetrault LLP               Latham & Watkins
    110 - 12th Avenue S.W.        Suite 3300, 421 - 7th Avenue     885 Third Avenue, Suite 1000
   Calgary, Alberta, Canada                   S.W.                   New York, New York 10022
           T2P 2M1                  Calgary, Alberta, Canada              (212) 906-1295
        (403) 267-7110                      T2P 4K9
                                         (403) 260-3657
</Table>

   APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE OF THE SECURITIES TO THE
                                    PUBLIC:
   FROM TIME TO TIME AFTER THE EFFECTIVE DATE OF THIS REGISTRATION STATEMENT.

                          PROVINCE OF ALBERTA, CANADA
       (Principal Jurisdiction Regulating This Offering (if Applicable))

It is proposed that this filing shall become effective (check appropriate box):


    A. / / Upon the filing with the Commission pursuant to Rule 467(a) (if in
           connection with an offering being made contemporaneously in the
           United States and Canada).



     B. / / At some future date (check the appropriate box below).


     1. / / Pursuant to Rule 467(b) on             (date) at             (time)
            (designate a time not sooner than seven calendar days after filing).

     2. / / Pursuant to Rule 467(b) on             (date) at             (time)
            (designate a time seven calendar days or sooner after filing)
            because the securities regulatory authority in the review
            jurisdiction has issued a receipt or notification of clearance on
                        (date).


     3. /X/ Pursuant to Rule 467(b) as soon as practicable after notification of
            the Commission by the registrant or the Canadian securities
            regulatory authority of the review jurisdiction that a receipt or
            notification of clearance has been issued with respect hereto.


     4. / / After the filing of the next amendment to this form (if preliminary
            material is being filed).


    If any of the securities being registered on this form are to be offered on
a delayed or continuous basis pursuant to the home jurisdiction's shelf
prospectus offering procedures, check the following box.   /X/


- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<Page>
                                     PART I

                           INFORMATION REQUIRED TO BE
                      DELIVERED TO OFFEREES OR PURCHASERS

                                      I-1
<Page>

                             BASE SHELF PROSPECTUS


<Table>
                                                                                 
[LOGO]                                      TRANSALTA CORPORATION
                                               US$1,000,000,000
                                                COMMON SHARES
                                            FIRST PREFERRED SHARES
                                               DEBT SECURITIES
                                                   WARRANTS
</Table>

    We may from time to time offer our common shares, first preferred shares,
debt securities or warrants to purchase common shares, first preferred shares,
debt securities or other securities (collectively, the "Securities"), up to a
total initial offering price of US$1,000,000,000 (or its equivalent in Canadian
dollars or any other currency or currency unit used to denominate the
Securities) during the 25 month period that this base shelf prospectus (the
"Prospectus"), including any amendments hereto, remains valid.

    NEITHER THE SECURITIES AND EXCHANGE COMMISSION (THE "SEC") NOR ANY STATE
SECURITIES COMMISSION OR OTHER REGULATORY BODY HAS APPROVED OR DISAPPROVED THESE
SECURITIES OR PASSED UPON THE ACCURACY OR ADEQUACY OF THIS PROSPECTUS. ANY
REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENCE.

    WE ARE PERMITTED TO PREPARE THIS PROSPECTUS IN ACCORDANCE WITH CANADIAN
DISCLOSURE REQUIREMENTS, WHICH ARE DIFFERENT FROM THOSE IN THE UNITED STATES. WE
PREPARE OUR FINANCIAL STATEMENTS IN ACCORDANCE WITH CANADIAN GENERALLY ACCEPTED
ACCOUNTING PRINCIPLES ("CANADIAN GAAP"), AND THEY ARE SUBJECT TO CANADIAN
AUDITING AND AUDITOR INDEPENDENCE STANDARDS. AS A RESULT, THEY MAY NOT BE
COMPARABLE TO FINANCIAL STATEMENTS OF UNITED STATES COMPANIES.

    OWNING THE SECURITIES MAY SUBJECT YOU TO TAX CONSEQUENCES BOTH IN THE UNITED
STATES AND CANADA. THIS PROSPECTUS MAY NOT DESCRIBE THESE TAX CONSEQUENCES
FULLY. YOU SHOULD READ THE TAX DISCUSSION UNDER "CERTAIN INCOME TAX
CONSIDERATIONS" AND IN ANY APPLICABLE PROSPECTUS SUPPLEMENT.

    YOUR ABILITY TO ENFORCE CIVIL LIABILITIES UNDER THE UNITED STATES FEDERAL
SECURITIES LAWS MAY BE AFFECTED ADVERSELY BECAUSE WE ARE INCORPORATED IN CANADA,
MOST OF OUR OFFICERS AND DIRECTORS AND SOME OF THE EXPERTS NAMED IN THIS
PROSPECTUS ARE CANADIAN RESIDENTS, AND MOST OF OUR ASSETS AND THE ASSETS OF
THOSE OFFICERS, DIRECTORS AND EXPERTS ARE LOCATED OUTSIDE OF THE UNITED STATES.

    The specific variable terms of any offering of Securities will be set forth
in a shelf prospectus supplement (a "Prospectus Supplement") including, where
applicable: (i) in the case of common shares, the number of shares offered and
the offering price; (ii) in the case of first preferred shares, the designation
of the particular series, the number of shares offered, the offering price, any
voting rights, any rights to receive dividends, any terms of redemption, any
conversion or exchange rights and any other specific terms; (iii) in the case of
debt securities, the specific designation of the debt securities, any limit on
the aggregate principal amount of the debt securities, the currency or currency
unit, the maturity, the offering price, whether payment on the debt securities
will be senior or subordinated to our other liabilities and obligations, whether
the debt securities will bear interest, the interest rate or method of
determining the interest rate, any terms of redemption, any conversion or
exchange rights and any other specific terms; and (iv) in the case of warrants,
the designation, number and terms of the common shares, first preferred shares,
debt securities or other securities purchasable upon exercise of the warrants,
and any procedures that will result in the adjustment of those numbers, the
exercise price, the dates and periods of exercise, and the currency in which the
warrants are issued and any other specific terms. We reserve the right to
include in a Prospectus Supplement specific variable terms pertaining to the
Securities that are not within the options and parameters set forth in this
Prospectus. You should read this Prospectus and any applicable Prospectus
Supplement before you invest.


    Our common shares are listed on the New York Stock Exchange (the "NYSE")
under the symbol "TAC" and on The Toronto Stock Exchange (the "TSX") under the
symbol "TA". There is currently no market through which the first preferred
shares, debt securities or warrants to purchase common shares, first preferred
shares, debt securities or other securities may be sold and purchasers may not
be able to resell such securities issued under this Prospectus.


    We may sell the Securities to or through underwriters or dealers purchasing
as principals, directly to one or more purchasers pursuant to applicable
statutory exemptions or through agents. See "Plan of Distribution". The
Prospectus Supplement relating to a particular offering of Securities will
identify each underwriter, dealer or agent engaged in connection with the
offering and sale of the Securities, and will set forth the method of
distribution of such Securities, including, to the extent applicable, the
proceeds to us and any fees, discounts or any other compensation payable to
underwriters, dealers or agents and any other material terms of the plan of
distribution.


                  THE DATE OF THIS PROSPECTUS IS MAY 14, 2002

<Page>
                               TABLE OF CONTENTS


<Table>
<Caption>
                                                                PAGE
                                                              --------
                                                           
About this Prospectus.......................................      2
Glossary....................................................      3
Where You Can Find More Information; Documents Incorporated
  by Reference..............................................      3
Special Note Regarding Forward-Looking Statements...........      5
The Corporation.............................................      5
Business of the Corporation.................................      6
Selected Consolidated Financial Data........................     21
Management..................................................     23
Use of Proceeds.............................................     23
Interest Coverage...........................................     23
Description of Share Capital................................     24
Description of Debt Securities..............................     27
Description of Warrants.....................................     40
Certain Income Tax Considerations...........................     41
Plan of Distribution........................................     41
Risk Factors................................................     42
Legal Matters...............................................     48
Experts.....................................................     48
Auditors....................................................     48
Documents Filed as Part of the Registration Statement.......     48
Enforcement of Civil Liabilities............................     48
</Table>


                             ABOUT THIS PROSPECTUS


    In this Prospectus and in any Prospectus Supplement, unless otherwise
specified or the context otherwise requires, all dollar amounts are expressed in
Canadian dollars. "U.S. dollars" or "US$" means lawful currency of the United
States. Unless otherwise indicated, all financial information included and
incorporated by reference in this Prospectus or included in any Prospectus
Supplement is determined using Canadian GAAP. "U.S. GAAP" means generally
accepted accounting principles in the United States. For a discussion of the
principal differences between our financial information as calculated under
Canadian GAAP and under U.S. GAAP, you should refer to note 26 of our
consolidated annual financial statements and the U.S. GAAP reconciliation to our
unaudited consolidated interim financial statements incorporated by reference
into this Prospectus. Except as set forth under "Description of Debt
Securities", and unless the context otherwise requires, all references in this
Prospectus and any Prospectus Supplement to "TransAlta", the "Corporation",
"we", "us" and "our" mean TransAlta Corporation and its consolidated
subsidiaries including any consolidated partnerships of which the Corporation or
any of its subsidiaries are partners.


    This Prospectus provides a general description of the Securities that we may
offer. Each time we sell Securities under this Prospectus, we will provide you
with a Prospectus Supplement that will contain specific information about the
terms of that offering. The Prospectus Supplement may also add, update or change
information contained in this Prospectus. Before investing, you should read both
this Prospectus and any applicable Prospectus Supplement together with
additional information described below under "Where You Can Find More
Information; Documents Incorporated by Reference."

                                       2
<Page>
                                    GLOSSARY

    This Prospectus and any Prospectus Supplement may include the following
terms:

"ALBERTA PPA" means an Alberta government mandated power purchase arrangement;

"GIGAWATT HOUR" or "GWH" means one million kilowatt hours of electrical power;

"KILOWATTS" or "KW" means 1,000 watts of electrical power;

"KILOWATT HOUR" or "KWH" means one hour during which one kilowatt of electrical
power has been continuously produced;

"MEGAWATT" or "MW" means 1,000 kilowatts of electrical power;

"MEGAWATT HOUR" or "MWH" means 1,000 kilowatt hours;

"PPA" means a power purchase agreement having an initial term of five years or
greater;

"WATT" means the scientific unit of electrical power, being the rate of energy
use that gives rise to the production of energy at a rate of one joule per
second; and

"WATT-HOUR" is a measure of energy production or consumption equal to one watt
produced or consumed for one hour.

                      WHERE YOU CAN FIND MORE INFORMATION;
                      DOCUMENTS INCORPORATED BY REFERENCE

    The following documents of the Corporation, filed with the Alberta
Securities Commission and with the SEC, are specifically incorporated by
reference in, and form an integral part of, this Prospectus provided that such
documents are not incorporated by reference to the extent that their contents
are modified or superseded by a statement contained in this Prospectus or in any
other subsequently filed document that is also incorporated by reference in this
Prospectus:

    (a) Consolidated annual financial statements and auditors' report for the
       years ended December 31, 2001 and 2000;

    (b) Management's discussion and analysis of financial condition and results
       of operations for the years ended December 31, 2001 and 2000;

    (c) Unaudited consolidated interim financial statements of the Corporation
       for the three month periods ended March 31, 2002 and 2001;

    (d) Management's discussion and analysis of the financial condition and
       results of operations for the three month periods ended March 31, 2002
       and 2001;

    (e) Annual Information Form of the Corporation dated May 1, 2002 (the
       "Annual Information Form");

    (f) Management Proxy Circular dated March 14, 2002 prepared in connection
       with the Corporation's annual meeting of shareholders held on May 1, 2002
       (excluding the sections entitled "Report on Executive Compensation",
       "Comparative Shareholder Return" and "Corporate Governance", which shall
       be deemed not to be incorporated by reference in this Prospectus);

    (g) the first two paragraphs of the Corporation's press release dated
       May 2, 2002 relating to the entering into of a memorandum of
       understanding with EPCOR Utilities Inc.; and

    (h) the reconciliation to U.S. GAAP of the unaudited consolidated interim
       financial statements of the Corporation for the three month periods ended
       March 31, 2002 and 2001.

    Any documents of the type referred to above (other than press releases
(including press releases disseminating financial information) unless indicated
in any applicable Prospectus Supplement) and material change reports (excluding
confidential material change reports) subsequently filed by the Corporation with
the Alberta Securities Commission after the date of this Prospectus and prior to
the termination of the offering of Securities shall be deemed to be incorporated
by reference into this Prospectus. These documents are available through the
internet on the System for Electronic Document Analysis and Retrieval (SEDAR)
which can be

                                       3
<Page>
accessed at www.sedar.com. In addition, any similar documents filed on Form 6-K
or Form 40-F by the Corporation with the SEC after the date of this Prospectus
shall be deemed to be incorporated by reference into this Prospectus and the
registration statement of which this Prospectus forms a part, if and to the
extent expressly provided in such report. The Corporation's reports on Form 6-K
are available on the SEC's website at www.sec.gov.

    ANY STATEMENT CONTAINED IN THIS PROSPECTUS OR IN A DOCUMENT INCORPORATED OR
DEEMED TO BE INCORPORATED BY REFERENCE HEREIN SHALL BE DEEMED TO BE MODIFIED OR
SUPERSEDED FOR PURPOSES OF THIS PROSPECTUS TO THE EXTENT THAT A STATEMENT
CONTAINED HEREIN OR IN ANY OTHER SUBSEQUENTLY FILED DOCUMENT WHICH ALSO IS OR IS
DEEMED TO BE INCORPORATED BY REFERENCE HEREIN MODIFIES OR SUPERSEDES SUCH
STATEMENT. THE MODIFYING OR SUPERSEDING STATEMENT NEED NOT STATE THAT IT HAS
MODIFIED OR SUPERSEDED A PRIOR STATEMENT OR INCLUDE ANY OTHER INFORMATION SET
FORTH IN THE DOCUMENT THAT IT MODIFIES OR SUPERSEDES. THE MAKING OF A MODIFYING
OR SUPERSEDING STATEMENT IS NOT TO BE DEEMED AN ADMISSION FOR ANY PURPOSES THAT
THE MODIFIED OR SUPERSEDED STATEMENT, WHEN MADE, CONSTITUTED A
MISREPRESENTATION, AN UNTRUE STATEMENT OF A MATERIAL FACT OR AN OMISSION TO
STATE A MATERIAL FACT THAT IS REQUIRED TO BE STATED OR THAT IS NECESSARY TO MAKE
A STATEMENT NOT MISLEADING IN LIGHT OF THE CIRCUMSTANCES IN WHICH IT WAS MADE.
ANY STATEMENT SO MODIFIED OR SUPERSEDED SHALL NOT BE DEEMED, EXCEPT AS SO
MODIFIED OR SUPERSEDED, TO CONSTITUTE A PART OF THIS PROSPECTUS.

    Upon a new annual information form and related consolidated comparative
annual financial statements and related management's discussion and analysis of
financial condition and results of operations being filed by us with and where
required, accepted by, the applicable securities regulatory authorities during
the currency of this Prospectus, the previous annual information form, the
previous consolidated comparative annual financial statements and related
management's discussion and analysis of financial condition and results of
operations and all interim financial statements and related management's
discussion and analysis of financial condition and results of operations,
material change reports and management proxy circulars filed prior to the
commencement of the Corporation's financial year in which the annual information
form is filed shall be deemed no longer to be incorporated into this Prospectus
for purposes of future offers and sales of Securities under this Prospectus.

    A Prospectus Supplement containing the specific terms of any Securities
offered thereunder will be delivered to purchasers of such Securities together
with this Prospectus and will be deemed to be incorporated by reference into
this Prospectus as of the date of the Prospectus Supplement solely for the
purposes of the offering of the Securities covered by that Prospectus
Supplement.

    Copies of the documents incorporated herein by reference (other than
exhibits to such documents, unless such exhibits are specifically incorporated
by reference in such documents) may be obtained on request without charge from
the Corporate Secretary of TransAlta, 110 - 12th Avenue S.W., Calgary, Alberta,
Canada, T2P 2M1, Telephone (403) 267-7110.

    The Corporation has filed with the SEC under the United States Securities
Act of 1933, as amended (the "U.S. Securities Act"), a registration statement on
Form F-10 relating to the Securities and of which this Prospectus is a part.
This Prospectus does not contain all of the information set forth in such
registration statement, certain items of which are contained in the exhibits to
the registration statement as permitted or required by the rules and regulations
of the SEC. See "Documents Filed as Part of the Registration Statement".
Statements made in this Prospectus as to the contents of any contract, agreement
or other document referred to are not necessarily complete, and in each
instance, reference is made to the exhibit for a more complete description of
the relevant matter, each such statement being qualified in its entirety by such
reference. Items of information omitted from this Prospectus but contained in
the registration statement may be inspected and copied at the public reference
facilities maintained at the offices of the SEC described below.

    The Corporation is subject to the information requirements of the United
States Securities and Exchange Act of 1934, as amended (the "U.S. Exchange
Act"), and in accordance therewith files reports and other information with the
SEC. Under the multi-jurisdictional disclosure system adopted by the United
States and Canada, such reports and other information may be prepared in
accordance with the disclosure requirements of Canada, which requirements are
different from those of the United States. The Corporation is exempt from the
rules under the U.S. Exchange Act prescribing the furnishing and content of
proxy statements, and its officers, directors and principal shareholders are
exempt from the reporting and short-swing profit recovery provisions contained
in Section 16 of the U.S. Exchange Act. Under the U.S. Exchange Act, the
Corporation is not required to publish financial statements as promptly as
United States companies. Such reports and other information may be inspected
without charge, and copied upon payment of prescribed fees, at the public
reference facility maintained by the SEC at 500 West Madison Street, Chicago,
Illinois 60661; and copies of such material may also be obtained from the Public
Reference Section of the SEC at 450 Fifth Street, N.W., Washington, D.C. 20549
at prescribed rates.

                                       4
<Page>
               SPECIAL NOTE REGARDING FORWARD-LOOKING STATEMENTS

    This Prospectus contains both historical and forward-looking statements
within the meaning of Section 27A of the U.S. Securities Act and Section 21E of
the U.S. Exchange Act. These forward-looking statements are not facts, but only
predictions and generally can be identified by the use of statements that
include phrases such as "believe," "expect," "anticipate," "intend," "plan,"
"foresee" or other words or phrases of similar import. Similarly, statements
that describe the Corporation's objectives, plans or goals also are
forward-looking statements. These forward-looking statements are subject to
risks and uncertainties which could cause actual results to differ materially
from those currently anticipated. Certain factors that could materially affect
these forward-looking statements are described below and can be found in this
Prospectus, including those factors described under the heading "Risk Factors".
Potential investors and other readers are urged to consider these factors
carefully in evaluating the forward-looking statements and are cautioned not to
place undue reliance on these forward-looking statements. The forward-looking
statements included in this Prospectus are made only as of the date of this
Prospectus and the Corporation does not undertake to publicly update these
forward-looking statements to reflect new information, future events or
otherwise. In light of these risks, uncertainties and assumptions, the
forward-looking events might or might not occur. The Corporation cannot assure
you that projected results or events will be achieved.

    Factors that may adversely impact the Corporation's forward-looking
statements include: (i) the rules and regulations in the various markets in
which the Corporation operates are subject to change; (ii) environmental
requirements and changes in, or liabilities under, these requirements;
(iii) risks under the Alberta PPAs, pursuant to which the Corporation operates
most of its facilities in Alberta, including risks associated with unplanned
outages; (iv) changes in the market prices and availability of fuel supplies
required to generate electricity, and in the price of electricity; (v) risks
relating to the operation of the Corporation's facilities; (vi) currency rate
risk and political uncertainty; (vii) trading risks and counterparty risks; and
(viii) rapid change and competition in the wholesale power industry.

    These and additional factors are described in more detail under "Risk
Factors" and in our Annual Information Form and our management's discussion and
analysis of financial condition and results of operations incorporated by
reference in our Annual Information Form.

                                THE CORPORATION

    The registered office and principal place of business of the Corporation are
at 110 - 12th Avenue S.W., Calgary, Alberta, Canada, T2P 2M1. TransAlta has two
principal operating subsidiaries, each incorporated under the federal laws of
Canada: TransAlta Utilities Corporation and TransAlta Energy Corporation.

                                       5
<Page>
                          BUSINESS OF THE CORPORATION

OVERVIEW

    The Corporation and its predecessors have been engaged in the production and
sale of electric energy since 1911. The Corporation is among Canada's largest
non-regulated electric generation and energy marketing companies with over
9,000 MW of generating capacity operating and under construction (of which
approximately 1,400 MW is under construction). The Corporation is focused on
generating electricity in Canada, the United States and Mexico through its
diversified portfolio of facilities fuelled by coal, gas and hydroelectric
power. The Corporation believes that it has positioned itself to capitalize on
opportunities created by the recent deregulation of the Alberta energy market
with its extensive facilities located in Alberta and its experience as a
developer of non-regulated independent power projects since 1992. On January 1,
2001, the Corporation's Alberta coal-fired and hydroelectric generating plants
began operating under the Alberta PPAs which established committed capacity and
electrical energy generation requirements and availability targets to be
achieved by each coal-fired plant, energy and ancillary services obligations for
the hydroelectric plants, and the price at which power would be supplied. The
Corporation also has several gas-fired cogeneration facilities in Ontario which
serve the Ontario market. In addition, the Corporation owns a 1,372 MW
coal-fired plant in Centralia, Washington and plans to build a 248 MW gas-fired
facility on the same site to supply electricity in the U.S. pacific northwest.
The Corporation has two facilities under construction in Mexico with a combined
capacity of 511 MW.

    On April 29, 2002, the Corporation completed the sale of its Alberta-based
transmission business to AltaLink, a consortium of companies comprised of SNC
Lavalin Energy, Trans-Elect Inc., the Ontario Teachers' Pension Plan and
Macquarie North America Ltd. The sale was carried out in furtherance of the
Corporation's strategy to focus on developing a portfolio of generation assets
capable of realizing the Corporation's financial objectives. The transmission
business segment was reclassified as a discontinued operation upon the
announcement in July 2001 of the agreement to sell the business.

    The Corporation is now organized into two business segments: generation
(which includes the former independent power projects group) and energy
marketing. The generation group is responsible for constructing and managing
power generation facilities. The energy marketing group is responsible for
managing the risks associated with the Corporation's generation assets.

BUSINESS STRATEGY

    The Corporation is focused on creating shareholder value through prudent
growth while maintaining a strong balance sheet. The Corporation intends to meet
its growth objectives by pursuing a strategy consisting of the following
elements:

    FOCUS ON OPERATIONAL EXCELLENCE.  The Corporation has set stringent
operational targets for its generation business. The Corporation is working to
reduce its already low production costs and to increase the availability of its
coal-fired and gas-fired plants to an average target of 90%. The performance
standards established by the Corporation for each of its generating units are
based on each unit's unique operating characteristics.

    INCREASE GENERATION CAPACITY.  The Corporation plans to increase its
generation capacity by at least 1,000 MW per year through to the end of 2005.
The Corporation intends to achieve this objective through a combination of
facility expansions, acquisitions and new development projects. The Corporation
seeks to prudently add generation capacity in markets which display attractive
supply and demand fundamentals and in which it can establish a significant
market presence. The Corporation has identified a number of cost-effective
opportunities to add capacity to its existing facilities, including additions to
its Alberta coal-fired facilities. The Corporation owns, leases or controls
extensive low sulfur coal reserves in Alberta capable of fuelling such
additional capacity. The Corporation has the ability under the Alberta PPAs to
sell such increased capacity into the spot market or directly to customers under
long-term arrangements.

    MANAGE RISK PROFILE.  The Corporation intends to develop facilities using a
variety of non-nuclear fuels in diverse markets across North America to mitigate
the price and regulatory risks associated with particular fuels and markets. In
connection with its new facilities, the Corporation intends to either enter into
long-term fuel

                                       6
<Page>
supply contracts that match PPAs or enter into PPAs that provide a flow-through
of fuel costs to the power purchaser. In addition to the Alberta PPAs, the
Corporation typically enters into staggered short-term contracts and other PPAs
to limit its exposure to price movements and optimize overall returns. The
Corporation manages supply risk from unplanned outages through proper plant
maintenance, FORCE MAJEURE clauses in contracts, insurance, and trading
activities. The Corporation will continue to work towards its objective of
having approximately 70% of its output governed by PPAs. These strategies are
intended to enable the Corporation to achieve positive, stable returns while
retaining the flexibility to capture favorable market opportunities when
available.

    LEVERAGE ENERGY MARKETING CAPABILITIES.  The Corporation will continue to
use energy marketing activities to manage and limit risk exposures from both
financial or physical positions and counterparty risks. The Corporation also
intends to leverage its energy marketing capabilities to identify and gain an
operational understanding of markets with attractive fundamentals to pursue
capacity additions. In addition, the Corporation will continue to seek
transmission access to execute physical trades and capture market opportunities.
See "Business of the Corporation -- Energy Marketing Business".

    PURSUE SUSTAINABLE DEVELOPMENT.  The Corporation believes that it conducts
its operation and development activities in a socially and environmentally
responsible manner. The Corporation plans to use a combination of new
technology, renewable resources, emissions trading and offsets to reduce its
emissions of greenhouse gas. In Canada, the Corporation has targeted zero net
emissions by 2024. Since establishing this emissions target, the Corporation has
entered into emissions trading arrangements to acquire offsets for over 250,000
tonnes of carbon dioxide. In 2000, the Corporation established a plan to invest
up to $100 million in sustainable development and research. Investments will be
made in new technologies to reduce carbon emissions, to further environmental
offset and credit use, and to develop renewable energy sources. As at March 31,
2002, the Corporation has invested approximately $23 million. Among its other
environmental activities, the Corporation is also developing methods of burning
coal in a more environmentally-friendly and efficient manner.

    EXERCISE FINANCIAL DISCIPLINE.  The Corporation will continue to exercise
financial discipline in acquiring, developing and operating facilities. This
discipline has enabled the Corporation as a non-regulated generation company to
preserve its investment grade rating. The Corporation views the maintenance of a
strong investment grade rating as important to providing it with ongoing access
to Canadian and international debt capital markets on attractive terms. Access
to equity capital will be achieved through the Corporation's prudent approach to
building its asset portfolio and supported by its TSX and NYSE listings.
Finally, the Corporation exercises portfolio discipline by continually reviewing
the rate of return of each of its assets and pursuing the sale of assets that
are not strategic or do not meet the Corporation's rate of return objectives.

MARKET OPPORTUNITIES

    As the largest generator of electricity in Alberta, measured by capacity,
and with generation assets in Ontario, the U.S. pacific northwest, Mexico and
Australia, the Corporation is well-positioned to capitalize on opportunities in
these regions. Alberta, located in Western Canada, is the country's fourth
largest province by population with approximately three million residents
representing 10% of Canada's total population. Alberta consumed approximately
49,403 GWh of electricity in 2001. As at December 31, 2001, the aggregate
installed capacity of generating facilities in Alberta was 11,588 MW.


    Ontario is Canada's largest province with approximately 12 million
residents, representing 38% of Canada's total population. Ontario consumed
approximately 150,000 GWh of electricity in 2001. Ontario Power
Generation Inc., the successor to the generation business of Ontario's former
integrated electric utility, controls over two-thirds of Ontario's approximately
30,000 MW of installed capacity, the balance of which is owned by municipal
electric utilities and private independent power producers or industrial
consumers.



    Power in the U.S. pacific northwest is regulated by the Western Electricity
Coordinating Council ("WECC"). The WECC is the largest of the 10 regions in the
North American Electric Reliability Council and is divided into four subregions,
of which Region 1 includes British Columbia, Alberta, Washington, Oregon, Idaho,
Montana, Utah, western Wyoming and northern Nevada. This subregion is referred
to as the Northwest Power Pool (the "NWPP"). Approximately 323,873 GWh of
electricity was generated in the NWPP in 2001. According


                                       7
<Page>

to the WECC, as of the summer 2001, aggregate generating capacity of
approximately 75,000 MW was located in the NWPP.


    The Corporation expects that the demand for electricity will continue to
grow in its target markets. In addition to increased demand, the market for
electricity in some of these regions has undergone deregulation. Legislation in
Alberta and Ontario and many states in the United States have mandated the
unbundling of services traditionally provided by vertically integrated utilities
to promote competition in the market for generation, transmission and
distribution of electricity. These regulatory changes have caused some
integrated utilities to sell all or parts of their generation assets. The
Corporation believes that the combination of increased demand for electricity,
deregulation and the increased availability of generation assets provides it
with an opportunity to increase its generation capacity and leverage its energy
marketing capabilities.

    In addition, the Corporation believes that the demand for electricity in
Mexico will continue to grow in the next several years due to the rapid rise of
manufacturing activity and increased commercial and consumer consumption. The
Corporation expects that the Government of Mexico's Comision Federal de
Electricidad ("CFE"), the state-owned and operated utility, will offer for
tender more independent power projects that are similar to those of the
Corporation's in Campeche and Chihuahua in order to meet this increase in demand
for electricity.

COMPETITIVE STRENGTHS

    The Corporation believes it is well-positioned to achieve its business
strategy due to its numerous competitive strengths, which include the following:

    STABLE CASHFLOW BASE.  As at March 31, 2002, approximately 90% of the
Corporation's existing aggregate production is contracted with counterparties
that meet the Corporation's risk management criteria. Approximately 63% of the
output is sold under Alberta PPAs, most of which expire from 2013 to 2020 and
are ultimately backed by the "Balancing Pool", an entity established by the
Government of Alberta. The Corporation expects that these Alberta PPAs will
provide a stable, long-term base for its cash flow and earnings. See "Generation
Business -- Alberta -- Alberta PPAs".

    OWNERSHIP OR CONTROL OF COAL SUPPLY.  The Corporation owns, controls or
leases extensive coal reserves in Alberta which provide a long-term and stable
source of fuel for approximately 85% of its generation capacity in Alberta. The
Corporation also owns a coal mine near its Centralia facility, which currently
provides approximately 70% of the fuel required at the Centralia facility. The
Corporation's mines in Alberta contain some of the cleanest burning coal in
North America, averaging 0.28% sulfur at the Whitewood mine and 0.19% at the
Highvale mine. Coal with lower sulfur content emits less sulfur dioxide
("SO(2)") when it is burned thereby minimizing environmental degradation. By
comparison the sulfur content of coal mined in the Powder River Basin typically
has sulfur content of about 0.45%.

    FINANCIAL STRENGTH.  The Corporation has investment grade issuer ratings
from Moody's Investor Services, Inc. and Standard & Poor's Corporation. The
Corporation expects that its financial strength will allow it to continue to
prudently take advantage of both acquisition opportunities and development
programs.

    GEOGRAPHIC DIVERSITY.  The Corporation has a geographically diverse asset
base with assets in Alberta, Ontario, the United States, Mexico and Australia.

    MANAGEMENT TEAM.  The Corporation's management team has substantial industry
and local markets experience and has successfully transformed the Corporation
from a regulated integrated utility to a deregulated electricity generator.

    ENERGY MARKETING EXPERTISE.  The Corporation's energy marketing group works
to enhance returns from its existing generation base. The energy marketing group
seeks to obtain more favorable pricing for uncommitted electricity, secure fuel
supply on a cost-effective basis and fulfill electricity delivery obligations in
the event of an outage.

                                       8
<Page>
GENERATION BUSINESS

    The following table summarizes the Corporation's generation facilities
operating and under construction:

<Table>
<Caption>
                                                  CAPACITY   OWNERSHIP                                               CONTRACT
REGION                          FACILITY            (MW)        (%)           FUEL            REVENUE SOURCE       EXPIRY DATE
- ------                  ------------------------  --------   ---------   --------------  ------------------------  ------------
                                                                                                 
ALBERTA                 Keephills...............     754         100          Coal       Alberta PPA                   2020
(20 FACILITIES)         Sheerness...............     732          50          Coal       Alberta PPA                   2020
                        Sundance................   2,029         100          Coal       Alberta PPA                   2020
                        Wabamun.................     569         100          Coal       Alberta PPA                   2003
                        Fort Saskatchewan.......     120          30          Gas        PPA                           2019
                        Meridian................     215          50          Gas        PPA                           2024
                        Poplar Creek............     360         100          Gas        Partial output PPA (3)        2024
                        Hydro assets (1)........     801         100         Hydro       Alberta PPA               2013 to 2020
                                                   -----
                                                   5,580
                                                   =====
ONTARIO                 Mississauga.............     110       50.01          Gas        PPA                           2017
(4 FACILITIES)          Ottawa Health Services..      68       50.01          Gas        PPA                           2012
                        Windsor-Essex...........      70       50.01          Gas        Partial output PPA (4)        2016
                        Sarnia (2)..............     650         100          Gas        Partial output PPA (5)        2022
                                                   -----
                                                     898
                                                   =====
UNITED STATES           Centralia...............   1,372         100          Coal       Partially contracted (6)       --
(4 FACILITIES)          Binghamton..............      55         100          Gas        Uncontracted                   --
                        Pierce..................     154     Leased           Gas        Contracted (6)                2002
                        Big Hanaford (2)........     248         100          Gas        Uncontracted                   --
                                                   -----
                                                   1,829
                                                   =====
MEXICO                  Campeche (2)............     252         100     Gas and Diesel  PPA                           2025
(2 FACILITIES)          Chihuahua (2)...........     259         100          Gas        PPA                           2026
                                                   -----
                                                     511
                                                   =====
AUSTRALIA               Parkeston...............     110          50          Gas        PPA                           2016
(2 FACILITIES)          Southern Cross..........     250          85          Gas        PPA                           2013
                                                   -----
                                                     360
                                                   =====
TOTAL                                              9,178
                                                   =====
</Table>

- ------------

(1) Comprised of 13 facilities.

(2) These facilities are currently under construction.

(3) Approximately 200 MW of the total 360 MW capacity are contracted under a
    PPA.

(4) Approximately 50 MW of the total 70 MW capacity are contracted under a PPA.

(5) Approximately 160 MW of the total 650 MW capacity are contracted under PPAs.

(6) Under agreements for full or partial output that are for terms of less than
    five years.

                                       9
<Page>
ALBERTA

COAL-FIRED FACILITIES

    The following table summarizes the Corporation's Alberta coal-fired
generation facilities:

<Table>
<Caption>
                                                  CAPACITY   OWNERSHIP   COMMISSIONING
LOCATION  PLANT                                     (MW)        (%)          DATES
- --------  -----                                   --------   ---------   -------------
                                                             
Wabamun   Wabamun Unit No. 1....................      69        100          1958
          Wabamun Unit No. 2....................      67        100          1956
          Wabamun Unit No. 3....................     147        100          1962
          Wabamun Unit No. 4....................     286        100          1968

Sundance  Sundance Unit No. 1...................     286        100          1970
          Sundance Unit No. 2...................     286        100          1973
          Sundance Unit No. 3...................     352        100          1976
          Sundance Unit No. 4...................     352        100          1977
          Sundance Unit No. 5...................     352        100          1978
          Sundance Unit No. 6...................     401        100          1980

Keephills Keephills Unit No. 1..................     377        100          1983
          Keephills Unit No. 2..................     377        100          1984

Sheerness Sheerness Unit No. 1..................     366         50          1986
          Sheerness Unit No. 2..................     366         50          1990
                                                   -----
TOTAL...........................................   4,084
                                                   =====
</Table>

    The Keephills, Sundance and Wabamun facilities are located approximately
70 kilometers west of Edmonton, Alberta. The Sheerness facility, which is
jointly owned by the Corporation and ATCO Power Ltd. ("ATCO Power"), is located
northeast of Calgary, Alberta.

    The Corporation's coal-fired plants are all base-load plants, meaning that
they are expected to operate for long periods of time at maximum output.
Availability, being the percentage of time that a plant is operating or
otherwise available for operation, is an important measure of the economic
success of a coal-fired plant. The historical average availability over the past
five years for the Corporation's coal-fired Alberta plant units is as follows:

<Table>
<Caption>
                                                               AVAILABILITY
                                                                    (%)
                                                            -------------------
PLANT                                                         HIGH       LOW      NO. OF UNITS
- -----                                                       --------   --------   ------------
                                                                         
Keephills.................................................    91.1       88.9          2
Sundance..................................................    90.4       86.7          6
Wabamun...................................................    89.8       64.1          4
Sheerness.................................................    83.1       81.9          2
</Table>

    The low availability for Wabamun is a result of a shut down from
August 2000 through June 2001 of one of its oldest units caused by cracking in
waterwall tubing. See "Business of the Corporation -- Legal Proceedings".

    Fuel for the Corporation's coal-fired facilities is supplied by nearby
surface strip coal mines that are owned, leased or controlled by the
Corporation. The Corporation owns two surface mines in Alberta which supply coal
to its facilities other than Sheerness. The Whitewood mine supplies the Wabamun
plant and the Highvale mine supplies the Sundance and Keephills plants. The
Corporation estimates that as at December 31, 2001 the recoverable coal reserves
contained in these mines are approximately 708 million tonnes which the
Corporation expects will be sufficient to meet the fuel requirements of these
plants for more than 50 years.

    Coal for the Sheerness plant is provided from the adjacent Sheerness mine,
which is jointly owned, leased or controlled by the Corporation and ATCO Power.
The Corporation and ATCO Power have executed coal supply agreements with
Luscar Ltd. which owns a portion of the coal reserves and operates the mine, to
supply coal until 2026.

                                       10
<Page>

    On February 5, 2001, the Corporation announced a proposal for a
$1.5 billion, 900 MW expansion at its Keephills facility. On February 12, 2002,
the Corporation received regulatory approval to proceed with the expansion. The
regulatory approval is currently under appeal by a third party. The Corporation
is in the process of updating the feasibility study factoring in the impact of
Alberta's transmission constraints, environmental requirements that may be
imposed by the EUB and market conditions to determine whether to pursue the
expansion. The Corporation currently expects to announce its plans in the second
half of 2002.


GAS-FIRED FACILITIES

    The following table summarizes the Corporation's Alberta gas-fired
generation facilities:

<Table>
<Caption>
                                                   CAPACITY   OWNERSHIP   COMMISSIONING
LOCATION           PLANT                             (MW)        (%)          DATES
- --------           -----                           --------   ---------   -------------
                                                              
Lloydminster       Meridian......................    215          50          1999
Fort McMurray      Poplar Creek..................    360         100          2001
Fort Saskatchewan  Fort Saskatchewan.............    120          30          1999
                                                     ---
TOTAL............................................    695
                                                     ===
</Table>

    The Meridian plant, a joint venture between the Corporation and Husky Oil
Operations Ltd., sells electricity to Saskatchewan Power Corporation, an agency
of the Province of Saskatchewan, and steam to the Husky Oil Lloydminster
Upgrader.

    The Poplar Creek plant provides electricity and steam to Suncor
Energy Inc.'s oil sands project. This 360 MW cogeneration facility became fully
operational in the first quarter of 2001 and delivers approximately 200 MW of
electricity and steam to Suncor. Any surplus power not used by Suncor is also
available for sale by the Corporation.

    The Corporation also holds an indirect interest in the 120 MW Fort
Saskatchewan gas-fired combined-cycle cogeneration facility in Alberta. The
Corporation's interest in the Fort Saskatchewan facility is held through
TransAlta Cogeneration, L.P. ("TA Cogen"), an Ontario limited partnership owned
50.01% by TransAlta and 49.99% by TransAlta Power, L.P. ("TA Power"), another
Ontario limited partnership. See "TransAlta Cogeneration, L.P. and TransAlta
Power, L.P."

HYDROELECTRIC FACILITIES

    The following table summarizes the Corporation's wholly-owned Alberta
hydroelectric facilities:

<Table>
<Caption>
                                                              CAPACITY   COMMISSIONING
LOCATION                         PLANT                        (MW)(1)        DATES
- --------                         -----                        --------   -------------
                                                                
Bow River system                 Horseshoe..................     14          1911
                                 Kananaskis.................     19       1913, 1951
                                 Ghost......................     51       1929, 1954
                                 Cascade....................     36       1942, 1957
                                 Barrier....................     13          1947
                                 Bearspaw...................     17         1953-54
                                 Pocaterra..................     15          1955
                                 Interlakes.................      5          1955
                                 Spray......................    103       1951, 1960
                                 Three Sisters..............      3          1951
                                 Rundle.....................     50       1951, 1960

North Saskatchewan River system  Brazeau....................    355       1965, 1967
                                 Bighorn....................    120          1972
                                                                ---
TOTAL.......................................................    801
                                                                ===
</Table>

       -------------------

        (1) Approximate capacity.

                                       11
<Page>
    The Corporation's hydroelectric facilities are primarily peaking plants,
meaning they are generally only operated during times of peak demand. The
productivity of these facilities is measured by "capacity factor", which is the
ratio of the net electricity generated compared to the electricity that could
have been generated had the plant been operating continuously at full-power. The
Bearspaw, Bighorn, Ghost, Horseshoe and Kananaskis plants have average five-year
capacity factors in excess of 40%, with the Horseshoe plant having the highest
five-year average capacity factor of 71%.

ALBERTA PPAS

    All of the Corporation's Alberta coal-fired and hydroelectric facilities
began operating under Alberta PPAs in January 2001.


    These Alberta PPAs established committed capacity and electrical energy
generation requirements and availability targets to be achieved by each
coal-fired plant, energy and ancillary services obligations for the
hydroelectric plants, and the price at which power would be supplied. The
Corporation bears the risk or retains the benefit of volume variances (except
for those arising from events considered to be FORCE MAJEURE, in the case of the
coal-fired plants), and any change in costs required to maintain and operate the
facilities.


    Under the Alberta PPAs for the coal-fired facilities, the Corporation is
exposed to electricity price risk in the event of an unplanned outage, other
than outages caused by an event of FORCE MAJEURE. In such circumstances, the
Corporation must pay a penalty for the lost production based upon a price equal
to the 30-day trailing average of Alberta's market electricity prices. The
Corporation mitigates this exposure through high-quality operating and
maintenance practices and hedging activities.

    The Corporation's hydroelectric facilities are not contracted on a facility
by facility basis, rather facilities are aggregated in a single Alberta PPA
which provides for energy and ancillary services obligations based on hourly
targets. These targeted amounts are established annually and they are met by the
Corporation through physical delivery or third party purchases.

    The Corporation's compensation under the Alberta PPAs is based on a pricing
formula which replaces the cost of service regime applicable under historical
utility regulation. Key elements of the pricing formula are the amount of common
equity deemed to form part of the capital structure and the amount of risk
premium attributable to deemed common equity. Common equity is deemed to be 45%
of total capital and the return on equity is set annually at a 4.5% premium over
the rate on a 10 year Government of Canada bond.

    The pricing formula includes a provision for site restoration costs of the
coal-fired generating plants. The Alberta PPAs do not provide compensation for
site restoration costs related to the Corporation's hydroelectric facilities.
The Corporation does not anticipate that its hydroelectric facilities will be
dismantled because of the water supply, irrigation, flood control and recreation
related purposes they serve.

    The expiry dates for the Corporation's Alberta PPAs, other than the Alberta
PPA for the Wabumun facility, range from 2013 to 2020. The Alberta PPA for the
Wabamun plant expires in 2003. Concurrent with the expiry of each Alberta PPA,
the applicable licenses from Alberta Environment and the Alberta Energy and
Utilities Board (the "EUB") terminate. The Corporation has procured an extension
of the licenses to operate the Wabamun plant until 2010 and intends to procure
extensions of the licenses for the other facilities upon the expiry of their
respective Alberta PPAs. Upon the expiry of the Alberta PPAs, the Corporation
will be able to sell its power output to the Alberta Power Pool and to third
party purchasers through direct sales agreements.


    The Alberta PPAs (together with legislation which applies thereto) permit
the Balancing Pool, directly or indirectly as successor to the power purchaser
under the Alberta PPAs, to terminate the Alberta PPAs in certain circumstances.
These termination provisions are similar to those found in some PPAs entered
into by government-related power purchasers. The Corporation will be entitled to
receive a lump sum payment in connection with any such termination, other than a
termination resulting from the Corporation's default. In any event, the
Corporation will thereafter be able to sell the output from any affected
facilities for its own account.


                                       12
<Page>
ONTARIO

    The Corporation's Ontario generating facilities are summarized in the
following table:

<Table>
<Caption>
                                                   CAPACITY   OWNERSHIP   COMMISSIONING
LOCATION     PLANT                                   (MW)        (%)          DATES
- --------     -----                                 --------   ---------   -------------
                                                              
Sarnia       Sarnia Regional(1)..................    650        100           2002
Ottawa       Ottawa Health Services..............     68        50.01         1992
Mississauga  Mississauga.........................    110        50.01         1992
Windsor      Windsor-Essex.......................     70        50.01         1996
                                                     ---
TOTAL............................................    898
                                                     ===
</Table>

- ------------

(1) This facility is currently under construction.

    The Ottawa Health Services plant is a combined-cycle cogeneration facility
designed to produce 68 MW of electrical energy. This capacity is sold under a
PPA with the Ontario Electricity Financial Corporation ("OEFC"), an agency of
the Province of Ontario. This agreement expires in 2012. The Ottawa Health
Services plant also provides steam to the member hospitals and treatment centers
of the Ottawa Health Sciences Centre, National Defence Medical Centre and the
Perley and Rideau Veterans' Health Centre.

    The Mississauga plant is a combined-cycle cogeneration facility designed to
produce 110 MW of electrical energy. This capacity is contracted under a PPA
with OEFC which expires expires in 2017. The plant also supplies steam,
compressed air, waste water treatment and de-ionized water to the Boeing
Canada Inc. manufacturing facility located adjacent to the Mississauga plant.

    The Windsor-Essex plant is a combined-cycle cogeneration facility designed
to produce 70 MW of electrical energy. Currently, 50 MW of the capacity is sold
under a PPA to OEFC. This agreement expires in 2016. The Corporation expects
deregulation to provide additional opportunities to sell additional capacity
into a competitive marketplace. The Windsor-Essex plant also provides steam and
compressed air to Chrysler Canada Ltd.'s mini-van assembly facility in Windsor.

    The Corporation's interest in the Mississauga, Ontario Health Services and
Windsor-Essex facilities in Ontario, are held through TA Cogen. See "TransAlta
Cogeneration, L.P. and TransAlta Power, L.P."

    The Corporation's 650 MW facility in Sarnia, Ontario is expected to be the
largest cogeneration facility in Canada. The Sarnia facility is comprised of a
440 MW gas-fired facility currently being built by the Corporation and an
existing 210 MW gas-fired plant acquired by the Corporation. The Corporation
anticipates the new 440 MW facility to be commissioned by the fourth quarter of
2002 and in commercial operation during 2003. The combined 650 MW facility will
provide steam and electricity to nearby facilities owned by Dow Chemical
Canada Inc., Bayer Inc., Nova Chemicals (Canada) Ltd. and Sunoco Inc. The
Corporation is committed to sell 25% of the capacity of the Sarnia facility
under PPAs and expects to sell the excess electricity into Ontario's power grid
and potentially the United States, subject to the deregulation of Ontario's
power market and transmission availability. The Corporation is negotiating
conditional power sales contracts and corresponding fuel supply contracts are
presently being negotiated for the uncommitted amount.

                                       13
<Page>
UNITED STATES

    The Corporation's generation facilities in the United States are summarized
in the following table:

<Table>
<Caption>
                                                    CAPACITY   OWNERSHIP   COMMISSIONING
LOCATION                 PLANT                        (MW)        (%)          DATES
- --------                 -----                      --------   ---------   -------------
                                                               
Centralia, Washington    Centralia Unit No. 1.....     670        100          1971
                         Centralia Unit No. 2.....     702        100          1971
                         Big Hanaford (1).........     248        100           N/A

Binghamton, New York     Binghamton...............      55        100          1992

Fredrickson, Washington  Pierce...................     154     Leased          2001
                                                     -----
TOTAL.............................................   1,829
                                                     =====
</Table>

       -------------------

        (1) This facility is currently under construction.

CENTRALIA

    The Corporation owns a two-unit 1,372 MW coal-fired facility and adjacent
mining operations located in Centralia, Washington, approximately 130 kilometers
south of Seattle, Washington.

    The Corporation sells power from the Centralia plant into the WECC, and in
particular, the U.S. pacific northwest energy market. Prior to the acquisition
of the Centralia plant and mine, the Corporation signed a number of medium to
long-term energy sales agreements for 87% of the plant's capacity. The
Corporation's target is to sell forward approximately 70% of its projected
output, leaving approximately 30% subject to sales at market prices.

    The Centralia mine produces approximately six million tonnes annually, or
approximately 70%, of the Centralia plant's annual coal requirements. The
Centralia mine's permitted coal reserves, being the amount of coal which can be
mined under the existing regulatory approval, are estimated to be 112 million
tonnes as at December 31, 2001, which represents approximately 19 years of
supply at current production levels. The Corporation currently imports the
balance of its coal requirements by rail using coal from the Powder River Basin
provided under short-term contracts.

BIG HANAFORD

    On April 10, 2001, the Corporation announced the construction of the Big
Hanaford gas-fired facility in Centralia, Washington, at a cost of
US$210 million. Once completed, the new facility will add 248 MW of electricity
to the U.S. pacific northwest energy market and will raise total capacity at
Centralia from 1,372 MW to 1,620 MW. Construction is expected to be completed by
July 2002.

BINGHAMTON

    The Corporation owns a 55 MW gas-fired peaking facility in Binghamton,
New York. This facility was commissioned in 1992 and is located near the
Pennsylvania and New York State borders. The Binghampton facility provides
electricity to the New York Power Pool during periods of high demand.

PIERCE

    The Corporation has installed seven simple-cycle gas-fired turbines at a
temporary generation facility located near Fredrickson, Washington. The
Corporation sells all of its output from this 154 MW facility into the WECC
under contracts. The Pierce facility is a short-term project that was designed
to address the energy needs in the U.S. pacific northwest and bridge the energy
gap until new generation becomes available in the region. The turbines are
leased from General Electric and will be returned at the end of 2002.

                                       14
<Page>
MEXICO

CAMPECHE

    On March 22, 2000, the Corporation and CFE entered into a 25-year PPA for
all of the output of the 252 MW dual fuel (gas and diesel), combined-cycle plant
in the State of Campeche, Mexico. The Corporation has also entered into a
related gas transportation agreement with CFE. CFE bears the price risk on fuel
under the PPA. Construction of the Campeche plant began in 2001 and commercial
operations are projected to commence in the first quarter of 2003. In addition
to the PPA and gas transportation agreement, the Corporation has entered into a
corresponding 25-year fuel supply agreement with Pemex Gas y Petro Quimica
Basica.

CHIHUAHUA

    On March 8, 2001, TransAlta announced it had won a competitive bid to build
and operate a 259 MW gas fired combined-cycle facility in Chihuahua, Mexico. The
Corporation entered into a 25-year PPA with CFE for all of the output of the
plant. The Corporation has also entered into a related gas transportation
agreement with CFE. CFE bears the price risk on fuel under the PPA. The
Corporation is currently considering a number of firm proposals for natural gas
fuel supply from high quality credit natural gas suppliers. Construction of the
plant began in the third quarter of 2001 and commercial operations are projected
to commence in mid-2003.

AUSTRALIA

    The Corporation holds interests in Western Australia consisting of: (i) the
110 MW Parkeston generation facility through a 50/50 joint venture with Normandy
Mining Limited; (ii) a partnership between the Corporation and the Australian
Gas Light Company, under which the Corporation has an 85% interest in the
250 MW Southern Cross gas-fired facility; and (iii) an 8.82% interest in a 1,380
kilometer gas transmission pipeline which delivers natural gas from the
Australian northwest shelf producing area to Western Australia.

TRANSALTA COGENERATION, L.P. AND TRANSALTA POWER, L.P.

    The Corporation's interest in the 120 MW Fort Saskatchewan gas-fired
cogeneration facility in Alberta, and the Mississauga, Ontario Health Services
and Windsor-Essex facilities in Ontario, are held through TA Cogen, an Ontario
limited partnership owned 50.01% by TransAlta and 49.99% by TA Power, another
Ontario limited partnership. The Corporation formed TA Cogen in 1998 to directly
or indirectly hold interests in generation facilities capable of producing
stable cash flows that would be distributed to TA Power's unitholders. The
partnership units of TA Power are publicly traded on the TSX.

    The Corporation is obligated to purchase all of the units of TA Cogen owned
by TA Power in 2018 at a price equal to the fair market value of the units, for
cash, common shares or a combination thereof.

ENERGY MARKETING BUSINESS

    The Corporation's energy marketing group was formed in 1995. The group has
largely been built by internal growth and has offices in Calgary, Alberta,
Portland, Oregon and Annapolis, Maryland.

    The energy marketing group derives revenue and earnings from the wholesale
trading of electricity and other energy-related commodities and derivatives. The
group's activities manage and limit risk exposures from both financial or
physical positions and counterparty risks. The group plays a strategic role in
managing risks and optimizing assets by assisting the Corporation in arranging
physical deliveries on contracted power obligations, while seeking to increase
the value of its electricity output.

    The key risk control activities of the energy marketing group include credit
review and approval, credit and performance risk measurement and monitoring,
validation of transactions, portfolio valuation and daily portfolio reporting
for the trading activities, including mark-to-market valuation, "value-at-risk"
("VAR") determination, which is a probabilistic measure providing the maximum
potential loss that the Corporation may incur at any given time due to
fluctuations in market energy prices, and application of other risk measurement

                                       15
<Page>
metrics. The Corporation's policy is to limit the group's aggregate VAR exposure
to $10 million at any point in time.

    An important factor in the group's trading success has been its ability to
access transmission capacity, which is necessary in order to be able to take
advantage of price differentials between regional markets. The group's trading
activities also provide market intelligence to improve corporate decision making
and provide entry points to new geographic markets.

    With the exception of transmission contracts, the fair value of all energy
trading activities is based on quoted market prices. The Corporation's
transmission trading strategy involves committing to make fixed payments for the
right, but not the obligation, to use electricity transmission. The fair value
of transmission contracts is based on quoted market prices and a spread option
valuation model. The Corporation's transmission contracts outstanding at
March 31, 2002 had a net fair value of $6.8 million. Realized and unrealized
changes in the fair value of energy trading contracts at the end of the first
quarter of 2002, exclusive of hedging transactions, were income of
$27.7 million and a loss of $28.8 million, respectively. There were no changes
in valuation techniques during the quarter.

    Maturities of energy trading contracts, exclusive of hedging transactions,
existing at March 31, 2002 over each of the next five years and thereafter is as
follows:


<Table>
<Caption>
                                                                    Fair value of contracts at period end
                                                 ----------------------------------------------------------------------------
                                                                                (in millions)
                                                                                                                    2007 AND
                                                  TOTAL       2002       2003       2004       2005       2006     THEREAFTER
                                                 --------   --------   --------   --------   --------   --------   ----------
                                                                                              
Prices actively quoted.........................   $(6.9)     $(7.9)     $(1.2)     $(0.1)     $(0.1)     $(0.1)       $ 2.5
Prices based on models or other valuation
  methods......................................     6.8        5.4        1.4       --         --         --          --
                                                  -----      -----      -----      -----      -----      -----        -----
                                                  $(0.1)     $(2.5)     $ 0.2      $(0.1)     $(0.1)     $(0.1)       $ 2.5
                                                  =====      =====      =====      =====      =====      =====        =====
</Table>


RISK MANAGEMENT POLICIES AND PROCEDURES

    The Corporation uses a multi-level risk management structure to manage the
Corporation's various risk and energy trading exposures. The Audit and
Environment Committee (the "A&E Committee") of the Corporation's board of
directors oversees corporate-wide risk management by reviewing the Corporation's
overall business risks. The Corporation's Chief Financial Officer reports to the
A&E Committee on at least a quarterly basis and is responsible for ensuring
compliance with the Corporation's financial and commodity risk exposure
management policies and procedures. These policies and procedures include limits
on exposures (commodity prices, insurance, currency, credit and interest rates),
reporting practices and other procedures necessary for the Corporation to manage
and control its financial and commodity exposures. The Corporation's Exposure
Management Committee (the "EM Committee") is responsible for reviewing,
monitoring and reporting on compliance of these financial and commodity risk
exposure management policies and procedures. The EM Committee is chaired by the
Chief Financial Officer and is comprised of the Director of Financial Operations
for each of the Corporation's business units, the Vice-President and Treasurer,
the Vice-President and Comptroller, the Director of Internal Audit, and the
Vice-President of Energy Marketing. The EM Committee is not a committee of the
board of directors of the Corporation and unlike the A&E Committee, does not
report to the board of directors.

ENVIRONMENTAL REGULATION

    The Corporation is subject to federal, provincial, state and local
environmental laws, regulations and guidelines concerning the generation and
transmission of electrical and thermal energy and surface mining. The
Corporation is committed to complying with or exceeding regulatory requirements
and to minimizing the environmental impact of its operations. The Corporation
works with governments and the public to develop appropriate frameworks to
protect the environment and, at the same time, achieve economic development.

                                       16
<Page>
CANADA

    In December 1997, the Government of Canada agreed, subject to subsequent
domestic ratification requirements, to a net reduction of emissions of
greenhouse gases from within Canada by 6% from 1990 levels by 2008 to 2012.
Canada's earlier target had been stabilization of such emissions at 1990 levels
by the year 2000. The Corporation is a significant emitter of carbon dioxide, a
greenhouse gas, and has been an active participant in the federal government's
Voluntary Challenge and Registry program. Under that program, the Corporation
has already reduced net emissions of greenhouse gases to below 1990 levels. An
important component of the program is offset projects which, through actions
taken at third-party sites, reduce the Corporation's greenhouse gas emissions on
a net basis. Because of the potential magnitude of the December 1997 commitment
made by the Government of Canada, the Corporation expects that offsets will need
to be a significant component of any national response.

    The Corporation's climate change strategy is designed to address the
potential competitive risks to its fossil-fuelled generation plants from future
public policy which could include environmental controls, regulatory regimes,
taxes or charges. The potential for higher electricity prices exists if new
policy does not permit cost-effective, market-based approaches for reducing
greenhouse gas emissions.

    The Corporation's climate change strategy contains the following key
components:

    - Reducing net emissions by improving the efficiency of the Corporation's
      existing operations; developing new high efficiency cogeneration
      facilities which produce lower overall emissions; acquiring a diverse
      portfolio of greenhouse gas offset projects; purchasing renewable energy;
      and promoting energy efficiency initiatives.

    - Participating in federal and provincial policy development.

    - Developing and testing market-based approaches, such as the trading of
      emission reduction credits.


    In 2000, the Corporation established a plan to invest up to $100 million in
sustainable development and research. Investments will be made in new
technologies to reduce carbon emissions, to further environmental offset and
credit use, and to develop renewable energy sources. As at March 31, 2002, the
Corporation has invested approximately $23 million. Among its other
environmental activities, the Corporation is also developing methods of burning
coal in a more environmentally-friendly and efficient manner.


UNITED STATES


    AIR EMISSIONS GENERALLY.  The Corporation's United States facilities are
subject to the federal Clean Air Act and many state laws and regulations
relating to air pollution. The pollutants subject to these laws and regulations
principally include, carbon monoxide ("CO"), SO(2), nitrogen oxides ("NO(x)"),
and particulate matter ("PM") and those contributing to the formation of
ground-level ozone ("O(3)"). As a general matter, the Corporation's generating
facilities emit these pollutants at levels within regulatory requirements.


    Prior to the Corporation's acquisition of the Centralia facility, the prior
owners agreed with the regulatory agencies to install scrubbers to reduce
certain pollutants, particularly SO(2) and PM, pursuant to a stipulated
schedule. The Corporation has assumed that obligation and the installation of
the first of the two scrubbers has been completed. The Corporation presently
expects that it will complete this project in accordance with its
legal obligations.


    In addition to the regulatory programs described below, further legislative
or administrative amendments to the air pollution regulations are possible,
including multi-pollutant legislation, regulation of green-house gas emissions,
and amendments to the regulations governing the permitting of new or modified
major sources of air pollutants. The Bush Administration's "Clear Skies
Initiative" proposes to reduce NO(x), SO(2), and mercury emissions from new and
existing facilities by approximately 70% through a mandatory "cap-and-trade"
program. Also, although the United States has not joined the international
treaty to reduce greenhouse gas emissions (the "Kyoto Protocols"), significant
international and public pressure to reduce greenhouse gas emissions still
exists and could result in adoption of new regulations applicable to facilities
in the United States. Depending upon the


                                       17
<Page>

stringency of these and other future requirements, the potential impact on the
Corporation's results of operation could be significant.


    NITROGEN OXIDES/OZONE.  Federal and state agencies have adopted rules
limiting the emission of NO(x) and volatile organic compounds ("VOC") from
fossil fuel-fired generating facilities. These new regulations include a more
stringent ambient air quality standard for ground-level ozone (formed by the
reaction of NO(x) and VOC with other compounds) and efforts to reduce the
formation and regional transport of NO(x) in the midwestern and eastern states.
Although these regulations are not anticipated to have a major effect on the
Corporation's existing facilities, they may affect future development plans.


    SULFUR DIOXIDE.  The acid rain provisions of the Clean Air Act require
substantial reductions in SO(2) emissions through a mandatory "cap and trade"
program for affected electric generating units. Marketable SO(2) allowances were
allocated to certain units that were in operation prior to November 1990. Units,
including new units, that emit SO(2) in excess of their allowances, must buy
excess allowances from other sources. The Corporation currently projects that it
will need to purchase SO(2) allowances for its Centralia operations. These
allowances are readily available on the market.


    VISIBILITY IMPAIRMENT AND REGIONAL HAZE.  EPA has promulgated regulations
seeking to reduce the impairment of visibility resulting from man-made
pollution. The regulations have been challenged in court. Even if the existing
rules are upheld, the extended compliance dates mean that the rules would not
have an impact on the Corporation until 2012 and beyond. However, this impact
may be significant. EPA's proposed rule defining the best available retrofit
technology ("BART") standard would require some existing facilities to reduce
haze-forming emissions by 90% or more. Depending upon the final versions of the
regulations that are implemented, the scrubbers presently being installed at the
Centralia facility may satisfy the Corporation's BART and Regional Haze
obligations. However, if additional pollution control measures are required, the
cost to the Corporation may be significant. Until the regulations are fully
adopted and all related administrative and judicial challenges are completed,
the precise impact on the Corporation cannot be determined.

    PARTICULATES.  In July 1997, EPA issued a new and more stringent national
ambient air quality standard for fine particulate matter. Future regulations
implementing the new standards could require further NO(x) and SO(2) reductions
in designated non-attainment areas. Because, EPA's designation of the affected
non-attainment areas was delayed due to litigation and is unlikely to be
completed until 2004 or 2005, the impact, if any, of the new fine particulate
matter standard on the Corporation's facilities can not be determined at this
time.

    NEW SOURCE REVIEW COMPLIANCE.  As part of a nationwide enforcement effort,
EPA and the U.S. Department of Justice have initiated enforcement actions
against a number of utilities for alleged violations of the Clean Air Act's
New Source Review permitting requirements related to past modifications of
existing coal-fired generating facilities. The recent scrubber installation at
the Centralia facility, which was subject to preconstruction review by the
applicable agencies, should reduce the Corporation's exposure to this
enforcement initiative.

    MERCURY.  Pursuant to Title III of the Clean Air Act, which requires
technology-based controls of hazardous air pollutant emissions from specific
industrial categories, EPA is under court order to propose a mercury-emissions
rule applicable to coal-fired facilities by December, 2003 and to promulgate a
final rule by December, 2004. Affected facilities must comply with the rule in
December, 2007. At present, the applicable control levels are uncertain, as are
the future costs of compliance.

WATER WITHDRAWALS AND DISCHARGES

    The federal Clean Water Act prohibits the discharge of any pollutants,
including heat, contaminated process water or storm water, into any body of
surface water, except in compliance with a discharge permit issued by EPA or a
delegated state agency. All of the Corporation's facilities are presently in
substantial compliance with these permitting obligations. The Corporation's
application for renewal of the Centralia facility and mine's national pollutant
discharge elimination system permit is currently under agency review. The
Corporation is not aware of any reason why the permit would not be reissued on
substantially similar terms as the current permit. However, there can be no
assurance that the results will be in accordance with the Corporation's
expectations.

                                       18
<Page>
    The Centralia facility and the 248-megawatt expansion now under construction
both rely on water withdrawals from the Skookumchuck River. The Centralia coal
mine also impacts tributaries of the Skookumchuck River. The effect of these
operations is being evaluated by the U.S. Fish and Wildlife Service and the
National Marine Fisheries Service for potential impact on certain fish that are
listed (or proposed for listing) as threatened species protected under the
federal Endangered Species Act ("ESA"). If the Corporation's operations are
found to harass or harm these species, the Corporation may be required to obtain
a permit and adopt measures to mitigate or eliminate the adverse impacts. There
can be no assurance that the results of this review will be in accordance with
the Corporation's expectations.

    EPA has adopted final rules establishing uniform, minimum technology
requirements on new cooling water intake structures. Similar rules for existing
intake structures were published by EPA in April of 2002. Based upon the
proposed rule, the Corporation does not anticipate that it will be required to
make significant modifications to its existing water intake structures. However,
the precise impact on the Corporation will not be known until the final
regulations are promulgated.

    In July 2000, EPA issued final rules for the implementation of the total
maximum daily load ("TMDL") program of the Clean Water Act. The goal of the TMDL
rules is to establish, over the next 15 years, the maximum amounts of various
pollutants that can be discharged into waterways while maintaining compliance
with water quality standards. The establishment of TMDL values may eventually
result in more stringent discharge permit limits that could require the
Corporation's facilities to install additional wastewater treatment, modify
operational practices or implement other wastewater control measures.
Implementation of the TMDL program remains controversial and the impact on the
Corporation, although potentially significant, cannot be determined.

SOLID WASTE AND TOXICS

    The Corporation's facilities are subject to the requirements of the Resource
Conservation and Recovery Act and the Comprehensive Environmental Response,
Compensation and Liability Act, along with other federal and state laws and
regulations. The Corporation believes that it is substantially compliant with
these requirements. In connection with the Corporation's acquisition of the
Centralia facility, it assumed certain environmental liabilities, which it does
not believe to be material. The prior owners retained any liabilities associated
with the facility's pre-acquisition offsite disposal practices.

    The ash generated by the Corporation's coal-fired generating facilities is
subject to regulation and must be disposed of at sites permitted under state and
local regulations. Regulatory changes seeking to classify coal ash as a
hazardous waste or otherwise restrict its disposal could increase the
Corporation's disposal costs facilities and potentially expose it to greater
liabilities for environmental remediation.

    The Corporation's Centralia assets are more than 30 years old, and as a
result contain asbestos insulation and other asbestos containing materials, as
well as lead-based paint. Existing state and federal rules require the proper
management and disposal of these potentially toxic materials. The Corporation
has established plans that call for the proper management of existing asbestos
containing materials and lead-based paint, and for their abatement and disposal
when needed. The cost of these efforts is included in the Corporation's
financial planning.

EMPLOYEES

    As of December 31, 2001, the Corporation had approximately 2,768 full and
part-time employees. Approximately 1,600 of the Corporation's employees belong
to labor unions. The Corporation is currently a party to nine different
collective bargaining agreements, with two additional collective bargaining
agreements presently being negotiated with unions that will represent workers at
the Mexican plants. The Corporation expects to conclude these negotiations by
2003. Of its nine existing collective bargaining agreements, the Corporation has
recently renewed four of the agreements and anticipates negotiating renewed
agreements with three others in 2002. The two remaining agreements continue to
be in force until 2003.

                                       19
<Page>
LEGAL PROCEEDINGS

    The Corporation is involved in various litigation and regulatory matters in
connection with its business. Other than the matters described below, the
Corporation does not believe that any of these matters will have a material
adverse effect on the Corporation.

WABAMUN PLANT SHUT DOWN

    On August 3, 2000, the 286 MW generating unit at the Wabamun plant ("Unit
No. 4"), the largest generating unit of the plant, was shut down when an
examination of its boiler indicated cracks in waterwall tubing. Unit No. 4 was
shut down until June 2001, when the tubing was replaced and the unit was
recommissioned.

    The Corporation was a party to two separate proceedings as a consequence of
the shut down. The first proceeding was a regulatory proceeding under the
Electric Utilities Act (Alberta) (the "EUA") relating to the period from
August 3, 2000 to December 31, 2000. The second proceeding was an arbitration
under the Wabamun PPA relating to the period from January 1, 2001 to June 8,
2001 when Unit No. 4 became fully operational.

    EUA REGULATORY PROCEEDING.  A hearing before the EUB was held in 2001 to
consider the Corporation's application for relief from certain payment
obligations under the EUA in relation to Unit No. 4. In its decision released in
December 2001, the EUB relieved the Corporation of approximately $11 million of
an $18 million obligation relating to the shut down of Unit No. 4 during 2000.

    PPA ARBITRATION.  The Corporation and the holder of the Wabamun Alberta PPA
arbitrated the consequences of the shut down of Unit No. 4 during 2001. The
arbitration hearing has been completed and the decision is pending.

    The Wabamun PPA contains FORCE MAJEURE provisions which suspend the
obligations of a party during the period that the event of FORCE MAJEURE is
operative. In the event that the shut down of Unit No. 4 is considered not to be
an event of FORCE MAJEURE, the Corporation will be required to make certain
penalty payments mandated by the Wabamun Alberta PPA, which aggregate
approximately $90 million. If the shut down is considered to be an event of
FORCE MAJEURE, the Corporation will not be subjected to any liability. The
Corporation cannot provide any assurance that it will be successful in defending
the claim for penalty payments under the Wabamun Alberta PPA.

                                       20
<Page>
                      SELECTED CONSOLIDATED FINANCIAL DATA

    The Corporation's selected consolidated financial data as at and for each of
the three years ended December 31, 1999, 2000 and 2001 have been derived from
its audited consolidated financial statements, certain of which have been
incorporated by reference in this Prospectus. The Corporation's selected
consolidated financial data for the three months ended March 31, 2001 and 2002
are derived from its unaudited interim consolidated financial statements
incorporated by reference in this Prospectus. The interim financial results
reflect all adjustments which, in the opinion of management, are necessary for a
fair statement of the results. Historical and interim results are not
necessarily indicative of the results to be expected in the future.


    The Corporation's consolidated financial statements are prepared in
accordance with Canadian GAAP. Canadian GAAP conforms in all material respects
with U.S. GAAP, except as described in note 26 to the Corporation's consolidated
financial statements for the years ended December 31, 2001 and 2000 and the
U.S. GAAP reconciliation for the three months ended March 31, 2002 and 2001,
incorporated by reference in this Prospectus. The selected consolidated
financial data should be read in conjunction with the Corporation's audited
consolidated annual financial statements and unaudited consolidated interim
financial statements, and the notes thereto, and management's discussion and
analysis of financial condition and results of operations related thereto
incorporated by reference in this Prospectus.


<Table>
<Caption>
                                                                                     THREE MONTHS ENDED
                                                      YEAR ENDED DECEMBER 31,             MARCH 31,
                                                  --------------------------------   -------------------
                                                    1999       2000        2001        2001       2002
                                                  --------   ---------   ---------   --------   --------
                                                             (AUDITED)                   (UNAUDITED)
                                                                      (IN MILLIONS)
                                                                                 
REVENUES........................................  $1,123.0   $ 2,802.5   $ 4,927.1   $1,390.6   $1,067.4
Trading purchases...............................    (272.0)   (1,202.5)   (2,533.7)    (684.1)    (647.7)
Fuel and purchased power........................    (216.6)     (655.8)   (1,288.7)    (411.4)    (173.8)
                                                  --------   ---------   ---------   --------   --------
GROSS MARGIN....................................     634.4       944.2     1,104.7      295.1      245.9

OPERATING EXPENSES:
Operations, maintenance and administration......     234.8       349.9       444.5       84.3       87.4
Depreciation and amortization...................     164.4       205.6       273.6       49.8       56.3
Taxes, other than income taxes..................      21.9        23.9        18.7        7.5        7.0
                                                  --------   ---------   ---------   --------   --------
                                                     421.1       579.4       736.8      141.6      150.7
OPERATING INCOME................................     213.3       364.8       367.9      153.5       95.2
Other income (expense)..........................     --           (1.1)        1.5       (1.5)      (2.0)
Foreign exchange gains..........................       1.7         0.1         0.8        0.7        0.6
Net interest expense............................     (65.5)      (91.4)      (88.1)     (33.9)     (19.2)
                                                  --------   ---------   ---------   --------   --------
EARNINGS FROM CONTINUING OPERATIONS BEFORE
  REGULATORY DECISIONS, INCOME TAXES AND
  NON-CONTROLLING INTERESTS.....................     149.5       272.4       282.1      118.8       74.6
Prior period regulatory decisions...............     --           44.1        11.0      --         --
                                                  --------   ---------   ---------   --------   --------
EARNINGS FROM CONTINUING OPERATIONS BEFORE
  INCOME TAXES AND NON-CONTROLLING INTERESTS....     149.5       316.5       293.1      118.8       74.6
Income taxes....................................      64.7       128.5        89.9       53.0       22.5
Non-controlling interests.......................      30.9        41.6        20.6        6.8        6.4
                                                  --------   ---------   ---------   --------   --------
Earnings from continuing operations.............      53.9       146.4       182.6       59.0       45.7
Earnings from discontinued operations...........     101.7        89.1        45.1       11.7       11.2
Net gain on disposal of discontinued
  operations....................................      19.7       266.8      --
Net earnings before extraordinary item..........     175.3       502.3       227.7       70.7       56.9
Extraordinary item..............................     --         (209.7)     --          --         --
                                                  --------   ---------   ---------   --------   --------
Net earnings....................................     175.3       292.6       227.7       70.7       56.9
Preferred securities distributions, net of
  tax...........................................       5.2        12.8        13.1        3.1        5.5
                                                  --------   ---------   ---------   --------   --------
NET EARNINGS APPLICABLE TO COMMON
  SHAREHOLDERS..................................     170.1       279.8       214.6       67.6       51.4
                                                  ========   =========   =========   ========   ========
Weighted average common shares outstanding in
  the year......................................     169.5       168.8       168.9      168.6      169.0
</Table>

                                       21
<Page>


<Table>
<Caption>
                                                                                     THREE MONTHS ENDED
                                                      YEAR ENDED DECEMBER 31,             MARCH 31,
                                                  --------------------------------   -------------------
                                                    1999       2000        2001        2001       2002
                                                  --------   ---------   ---------   --------   --------
                                                             (AUDITED)                   (UNAUDITED)
                                                                      (IN MILLIONS)
                                                                                 
BALANCE SHEET DATA (AT PERIOD END):
Current assets..................................  $  615.5   $ 1,803.0   $ 1,432.4   $1,850.9   $1,426.7
Capital assets (net of accumulated
  depreciation).................................   5,031.0     5,277.1     6,124.4    7,804.5    6,280.5
Total assets....................................   6,038.4     7,627.1     7,877.9    7,524.3    8,066.3
Current liabilities.............................     956.3     2,076.4     1,812.2    2,072.6    1,937.0
Long-term debt..................................   1,965.6     2,121.8     2,406.8    2,040.0    2,437.2
Total liabilities...............................   3,270.0     5,002.7     5,154.6    4,889.5    5,323.4
Non-controlling interests.......................     645.7       375.0       281.0      371.8      281.6
Preferred securities............................     287.1       292.0       452.6      285.9      452.3
Common shareholders' equity.....................   1,835.6     1,957.4     1,989.7    1,977.1    2,009.0
Total shareholders' equity......................   2,122.7     2,249.4     2,442.3    2,263.0    2,461.3

OTHER DATA (UNAUDITED):
Earnings before interest, taxes and
  non-controlling interests (1).................  $  439.6   $   605.6   $   466.6   $  176.8   $  116.2
Earnings before interest and taxes, depreciation
  and amortization (1)..........................     765.1       927.3       792.5      242.4      187.1
Cash flow from operating activities before
  change in working capital.....................     477.7       616.9       624.5      137.3      171.3
Capital expenditures............................     644.9       795.0     1,246.5      161.4      269.3
Acquisitions....................................     347.6       880.1         9.8      --         --

KEY RATIOS (UNAUDITED):
Cash flow to interest (2).......................       4.0x        4.6x        4.9x       4.7x       5.6x
Cash flow to total debt (3).....................        21%         26%         23%        27%        24%
Total debt to total capitalization (4)..........        46%         50%         53%        46%        55%
</Table>


- ------------

(1) Includes discontinued operations.

(2) Cash flow from operations before changes in working capital and gross
    interest expense divided by gross interest expense.

(3) Cash flow from operations before changes in working capital divided by the
    two-year average of total debt.

(4) Total debt divided by the sum of total debt, non-controlling interests,
    preferred shares, preferred securities and common shareholders' equity.

                                       22
<Page>
                                   MANAGEMENT

    The directors and executive officers of the Corporation are set out below.

<Table>
<Caption>
NAME                            POSITION
- ----                            --------
                             
Stephen G. Snyder.............  President, Chief Executive Officer and Director
Ian A. Bourne.................  Executive Vice President and Chief Financial Officer
James F. Dinning..............  Executive Vice President, Sustainable Development & External Relations
Dawn L. Farrell...............  Executive Vice President, Corporate Development
James W. Kemp.................  Executive Vice President, Generation
Kenneth S. Stickland..........  Executive Vice President, Legal
John T. Ferguson (1)(2)(3)....  Director, Chairman of the Board
Stanley J. Bright (1).........  Director
Roderick S. Deane (1).........  Director
Jack C. Donald (2)............  Director
Gordon D. Giffin..............  Director
Christopher Hampson (1).......  Director
Charles H. Hantho (2)(3)......  Director
Louis D. Hyndman (2)(3).......  Director
Donna S. Kaufman (1)(3).......  Director
John S. Lane (1)(3)...........  Director
Luis Vazquez Senties..........  Director
Ralph A. Thrall, Jr. (2)......  Director
</Table>

- ------------

(1) Member of Audit and Environment Committee.

(2) Member of Human Resources Committee.

(3) Member of Nominating and Corporate Governance Committee.

                                USE OF PROCEEDS

    Unless otherwise specified in a Prospectus Supplement, the net proceeds from
the sale of the Securities will be used for general corporate purposes,
including the repayment of indebtedness and the financing of the Corporation's
long-term investment plan. The amount of net proceeds to be used for any such
purpose will be set forth in a Prospectus Supplement. The Corporation expects
that it may, from time to time, issue securities (including debt securities)
other than pursuant to this Prospectus.

                               INTEREST COVERAGE

    The following financial ratios have been calculated on a consolidated basis
for the respective 12 month periods ended December 31, 2001 and March 31, 2002
and are based on audited financial information, in the case of the 12 month
period ended December 31, 2001, and unaudited financial information, in the case
of the 12 month period ended March 31, 2002. The following ratios do not give
effect to the issue of any debt securities pursuant to this Prospectus. The
following financial ratios do not purport to be indicative of interest coverage
ratios for any future periods. The financial ratios have been calculated based
on Canadian GAAP.

<Table>
<Caption>
                                                              DECEMBER 31,    MARCH 31,
                                                                  2001           2002
                                                              -------------   ----------
                                                                        
Interest coverage on long-term debt.........................   2.80 times     2.55 times
</Table>

    Interest coverage on long-term debt is equal to net earnings before interest
on long-term debt and income taxes divided by interest expense on long-term
debt. For purposes of calculating the above ratio, long-term debt includes the
current portion of long-term debt and does not include any amounts with respect
to debt securities that may be issued under this Prospectus. Additionally, the
above ratios have been calculated without including the annual carrying charges
relating to the equity component of the $175 million aggregate principal amount
of

                                       23
<Page>
7.50% preferred securities due April 13, 2048, the $125 million aggregate
principal amount of 8.15% preferred securities due December 31, 2048 and the
$175 million aggregate principal amount of 7.75% preferred securities due
December 31, 2050 of the Corporation (collectively, the "Preferred Securities").
If the equity component of the Preferred Securities was classified as debt, the
entire carrying charges of the Preferred Securities would be included in
interest expense. If these annual carrying charges had been included in the
calculations, the interest coverage would have been 2.46 times for the 12 month
period ended December 31, 2001 and 2.20 times for the 12 month period ended
March 31, 2002. Under U.S. GAAP, the Preferred Securities would be classified as
debt and the entire carrying charges of the Preferred Securities would be
included in interest expense.

                          DESCRIPTION OF SHARE CAPITAL

GENERAL

    As of the date of this Prospectus, the Corporation's authorized share
capital consists of an unlimited number of common shares and an unlimited number
of first preferred shares, issuable in series. As at March 31, 2002,
168.7 million common shares were outstanding and no first preferred shares
were outstanding.

COMMON SHARES

    Each common share of the Corporation entitles the holder thereof to one vote
for each common share held at all meetings of shareholders of the Corporation,
except meetings at which only holders of another specified class or series of
shares are entitled to vote, to receive dividends if, as and when declared by
the board of directors, subject to prior satisfaction of preferential dividends
applicable to any first preferred shares, and to participate ratably in any
distribution of the assets of the Corporation upon a liquidation, dissolution or
winding up, subject to prior rights and privileges attaching to the first
preferred shares. The common shares are not convertible and are not entitled to
any pre-emptive rights. The common shares are not entitled to
cumulative voting.

    The transfer agent and registrar for the common shares in Canada is
CIBC Mellon Trust Company at its principal transfer office in Vancouver, British
Columbia, Calgary, Alberta, Winnipeg, Manitoba, Toronto, Ontario and Montreal,
Quebec. The transfer agent and registrar for the common shares in the United
States is Mellon Investor Services LLC at its principal office in New York,
New York.

    The common shares offered pursuant to this Prospectus may include shares
available for purchase under the Corporation's Dividend Reinvestment and Share
Purchase Plan and any shares issuable upon conversion or exchange of any first
preferred shares or debt securities of any series or upon exercise of any
options or warrants.

FIRST PREFERRED SHARES

    The Corporation is authorized to issue an unlimited number of first
preferred shares, issuable in series and, with respect to each series, the board
of directors is authorized to fix the number of shares comprising the series and
determine the designation, rights, privileges, restrictions and conditions
attaching to such shares, subject to certain limitations.

    The first preferred shares of all series rank senior to all other shares of
the Corporation with respect to priority in payment of dividends and with
respect to distribution of assets in the event of liquidation, dissolution or
winding up of the Corporation, or a reduction of stated capital. Holders of
first preferred shares are entitled to receive cumulative quarterly dividends on
the subscription price thereof as and when declared by the board of directors at
the rate established by the board of directors at the time of issue of shares of
a series. No dividends may be declared or paid on any other shares of the
Corporation unless all cumulative dividends accrued upon all outstanding first
preferred shares have been paid or declared and set apart. In the event of the
liquidation, dissolution or winding up of the Corporation, or a reduction of
stated capital, no sum shall be paid or assets distributed to holders of other
shares of the Corporation until the holders of first preferred shares shall have
been paid the subscription price of the shares, plus a sum equal to the premium
payable on a redemption, plus a sum equal to the arrears of dividends
accumulated on the first preferred shares to the date of such liquidation,
dissolution, winding up, or reduction of stated capital, as applicable. After
payment of such amount, the holders of first preferred shares shall not be
entitled to share further in the distribution of the assets of the Corporation.

                                       24
<Page>
    The directors may include in the share conditions attaching to a particular
series of first preferred shares certain voting rights effective upon the
Corporation failing to make payment of six quarterly dividend payments, whether
or not consecutive. These voting rights continue for so long as any dividends
remain in arrears. These voting rights are the right to one vote for each $25 of
subscription price on all matters in respect of which shareholders vote, and
additionally, the right of all series of first preferred shares, voting as a
combined class, to elect two directors of the Corporation if the board of
directors then consists of less than 16 directors, or three directors if the
board of directors consists of 16 or more directors. Otherwise, except as
required by law, the holders of first preferred shares shall not be entitled to
vote or to receive notice of or to attend at any meeting of the shareholders of
the Corporation.

    Subject to the share conditions attaching to any particular series providing
to the contrary, the Corporation may redeem first preferred shares of a series,
in whole or from time to time in part, at the redemption price applicable to
each series and the Corporation has the right to acquire any of the first
preferred shares of one or more series by purchase for cancellation in the open
market or by invitation for tenders at a price not to exceed the redemption
price applicable to the series.

    The Prospectus Supplement will set forth the following terms relating to the
first preferred shares being offered:

    - the maximum number of shares;

    - the designation of the series;

    - the offering price;

    - the annual dividend rate and whether the dividend rate is fixed or
      variable, the date from which dividends will accrue, and the dividend
      payment dates;

    - the price and the terms and conditions for redemption, if any, including
      redemption at TransAlta's option or at the option of the holder, including
      the time period for redemption, and payment of any accumulated dividends;

    - the terms and conditions, if any, for conversion or exchange for shares of
      any other class of TransAlta or any other series of first preferred
      shares, or any other securities or assets, including the price or the rate
      of conversion or exchange and the method, if any, of adjustment;

    - whether such first preferred shares will be listed on any securities
      exchange;

    - the voting rights, if any; and

    - any other rights, privileges, restrictions, or conditions.

    First preferred shares will be fully paid and nonassessable upon issuance.
The first preferred shares of any series may be represented, in whole or in
part, by one or more global certificates. If first preferred shares are
represented by a global certificate, each global certificate will:

    - be registered in the name of a depositary or a nominee of the depositary
      identified in the Prospectus Supplement; and

    - be deposited with such depositary or nominee or a custodian for
      the depositary.

RELATED PARTY ARTICLES PROVISIONS

    The Articles of the Corporation contain provisions restricting the ability
of the Corporation to enter into a "Specified Transaction" with a "Major
Shareholder". A Specified Transaction requires the approval of a majority of the
votes cast by holders of voting shares of the Corporation, as well as the
approval of a majority of the votes cast by holders of such shares, excluding
any Major Shareholder. A Major Shareholder generally means the beneficial owner
of more than 20% of the outstanding voting shares of the Corporation. There is a
broad definition of beneficial ownership, and in particular, a person is
considered to beneficially own shares owned by its associates and affiliates, as
those terms are defined in the Articles. Transactions which are considered to be
Specified Transactions include the following: a merger or amalgamation of the
Corporation

                                       25
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with a Major Shareholder; the furnishing of financial assistance by the
Corporation to a Major Shareholder; certain sales of assets or provision of
services by the Corporation to a Major Shareholder or vice versa; certain
issuances of securities by the Corporation which increase the proportionate
voting interest of a Major Shareholder; a reorganization or recapitalization of
the Corporation which increases the proportionate voting interest of a Major
Shareholder; and the creation of a class or series of non-voting shares of the
Corporation which has a residual right to participate in earnings of the
Corporation and assets of the Corporation upon dissolution or winding up.

SHAREHOLDER RIGHTS PLAN

    The Corporation implemented a shareholder rights plan (the "Rights Plan")
pursuant to a Shareholder Bid Approval Plan Agreement (the "Rights Plan
Agreement") dated as of October 13, 1992 between the Corporation and
CIBC Mellon Trust Company, as amended. The common shareholders of the
Corporation reconfirmed the Rights Plan and approved the amendments to the
Rights Plan Agreement, as set out in the Corporation's Information Circular
dated March 9, 2001, at the May 3, 2001, Annual and Special Meeting
of Shareholders. The following is a summary of certain material provisions of
the Rights Plan Agreement, and does not purport to be complete. For further
particulars, reference should be made to the Rights Plan Agreement.

    Pursuant to the Rights Plan Agreement, upon each issuance of a common share
of the Corporation, one right (a "Right") is automatically issued with and
attaches to the common share.

    The Rights will separate from the common shares and will be exercisable
eight trading days (or later, if determined by the board of directors) (the
"Separation Time") after a person has acquired beneficial ownership of or
commenced a take-over bid to acquire 20% or more of the common shares, other
than by an acquisition pursuant to a take-over bid permitted by the Rights Plan
(a "Permitted Bid"). The Rights Plan Agreement contains a broad definition of
beneficial ownership, which includes common shares held by associates and
affiliates of a person, as those terms are defined in the Rights Plan Agreement.
The acquisition by any person (an "Acquiring Person") of beneficial ownership of
20% or more of the common shares, other than by way of a Permitted Bid, is
referred to as a "Flip-in Event". Any Rights held by an Acquiring Person will
become void upon the occurrence of a Flip-in Event. Eight trading days after the
occurrence of the Flip-in Event, each Right (other than those held by the
Acquiring Person), will permit the purchase of $160 worth of common shares
for $80.

    In order to constitute a Permitted Bid, an offer must be made in compliance
with the Rights Plan and must be made to all shareholders (other than the
offeror), and must be outstanding for a minimum period of 60 days and common
shares tendered pursuant to the offer may not be taken up prior to the expiry of
the 60 day period and only if at such time more than 50% of the common shares
held by shareholders, other than offeror, its affiliates and persons acting
jointly or in concert and certain other persons (the "Independent
Shareholders"), have been tendered to the offer and not withdrawn. If more than
50% of the common shares held by Independent Shareholders are tendered to the
offer within the 60 day period, the offeror must make a public announcement of
that fact and the offer must remain open for deposits of common shares for an
additional 10 business days from the date of such public announcement.

    The issue of the Rights is not initially dilutive. Upon a Flip-in Event
occurring and the Rights separating from the common shares, reported earnings
per share on a fully diluted or non-diluted basis may be affected. Holders of
Rights not exercising their Rights upon the occurrence of a Flip-in Event may
suffer substantial dilution.

                                       26
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                         DESCRIPTION OF DEBT SECURITIES


    In this section, the terms "Corporation" and "TransAlta" refer only to
TransAlta Corporation without its subsidiaries through which it operates. The
following description sets forth certain general terms and provisions of the
debt securities. The Corporation will provide particular terms and provisions of
a series of debt securities and a description of how the general terms and
provisions described below may apply to that series in a Prospectus Supplement.


    The debt securities will be issued under an indenture (the "Indenture") to
be entered into between TransAlta and The Bank of New York, as trustee (the
"Trustee"). The Indenture will be subject to and governed by the U.S. Trust
Indenture Act of 1939, as amended. A copy of the form of Indenture has been
filed as an exhibit to the registration statement. The following is a summary of
the Indenture. Whenever there are references to particular provisions of the
Indenture, those provisions are incorporated by reference as part of the
statements made in this Prospectus and are qualified in their entirety by
reference to the Indenture. References in parentheses are to section numbers of
the Indenture.

    The Corporation may issue debt securities and incur additional indebtedness
other than through the offering of debt securities pursuant to this Prospectus.

GENERAL

    The Indenture does not limit the aggregate principal amount of debt
securities which may be issued under the Indenture. It provides that debt
securities will be in registered or bearer form, may be issued from time to time
in one or more series and may be denominated and payable in U.S. dollars or any
other currency. Material Canadian and United States federal income tax
considerations applicable to any debt securities, and special tax considerations
applicable to the debt securities denominated in a currency or currency unit
other than Canadian or U.S. dollars, will be described in the Prospectus
Supplement relating to the offering of debt securities.

    The Prospectus Supplement will set forth the following terms relating to the
debt securities being offered:

    - the specific designation and any limit on the aggregate principal amount
      of the debt securities;

    - the extent and manner, if any, to which payment on or in respect of the
      debt securities will be senior or will be subordinated to the prior
      payment of other liabilities and obligations of TransAlta;

    - the percentage or percentages of principal amount at which the debt
      securities will be issued;

    - the date or dates on which the principal of (and premium, if any, on) the
      debt securities will be payable and the portion (if less than the
      principal amount) to be payable upon a declaration of acceleration
      of maturity;

    - the rate or rates (whether fixed or variable) at which the debt securities
      will bear interest, if any (or the manner of calculation thereof) and the
      date or dates from which such interest will accrue;

    - the dates on which any interest will be payable and the regular record
      dates for the payment of interest on debt securities in registered form;

    - the place or places where the principal of (and premium, if any) and
      interest, if any, on the debt securities will be payable and each office
      or agency where the debt securities may be presented for registration of
      transfer or exchange;


    - the currency or currency unit in which the debt securities are denominated
      or in which payment of the principal of (and premium, if any) and
      interest, if any, on such debt securities will be payable;


    - whether debt securities will be issuable in the form of one or more global
      securities and if so the identity of the depository for the
      global securities;

    - any mandatory or optional sinking fund provisions;

    - the period or periods, if any, within which, the price or prices at which,
      the currency or currency unit in which, and the terms and conditions upon
      which, the debt securities may be redeemed or purchased by TransAlta;

                                       27
<Page>
    - the terms and conditions, if any, upon which TransAlta or the purchaser
      may redeem debt securities prior to maturity and the price or prices at
      which and the currency or currency unit in which the debt securities
      are payable;

    - any index used to determine the amount of payments of principal of (and
      premium, if any) or interest, if any, on the debt securities;

    - the terms, if any, on which the debt securities may be converted or
      exchanged for other securities of TransAlta or other entities;

    - whether and under what circumstances TransAlta will pay additional amounts
      on the debt securities in respect of certain taxes (and the terms of any
      such payment) and, if so, whether TransAlta has the right to redeem the
      debt securities of any series rather than pay the additional amounts (and
      terms of any such right);

    - any other terms of the debt securities including covenants and Events of
      Default which apply solely to a particular series of debt securities being
      offered which do not apply generally to the debt securities, or any
      covenants or Events of Default generally applicable to debt securities
      which do not apply to a particular series of debt securities;

    - whether such debt securities will be listed on any securities exchange;

    - whether the debt securities of the series are to be issuable as registered
      securities, bearer securities (with or without coupons) or both; and

    - if other than denominations of US$1,000 and any integral multiple thereof,
      the denominations in which any registered securities of the series shall
      be issuable and, if other than the denomination of US$5,000, the
      denomination or denominations in which any bearer securities of the series
      shall be issuable. (Section 3.1)

    Unless otherwise indicated in the applicable Prospectus Supplement, the
Indenture does not afford the holders the right to tender debt securities to
TransAlta for repurchase or provide for any increase in the rate or rates of
interest at which the debt securities will bear interest, in the event TransAlta
should become involved in a highly leveraged transaction or in the event of a
change in control of TransAlta.

    Debt securities may be issued under the Indenture bearing no interest or
interest at a rate below the prevailing market rate at the time of issuance, and
may be offered and sold at a discount below their stated principal amount.
(Section 3.1) The Canadian and United States federal income tax consequences and
other special considerations applicable to any such discounted debt securities
or other debt securities offered and sold at par which are treated as having
been issued at a discount for Canadian and/or United States federal income tax
purposes will be described in the applicable Prospectus Supplement.

    Unless otherwise indicated in the applicable Prospectus Supplement,
TransAlta may, without the consent of the holders thereof, reopen a previous
issue of a series of debt securities and issue additional debt securities of
such series.

RANKING AND OTHER INDEBTEDNESS

    Unless otherwise indicated in an applicable Prospectus Supplement, the debt
securities will be unsecured obligations and will rank equally with all of the
Corporation's other unsecured and unsubordinated indebtedness. TransAlta
conducts a significant amount of its operations through its subsidiaries. As at
March 31, 2002, TransAlta's subsidiaries had outstanding $1,173.7 million
aggregate principal amount of long-term debt. The debt securities issued under
this Prospectus will be structurally subordinated to all existing and future
liabilities, including trade payables and other indebtedness of TransAlta's
subsidiaries. See "Risk Factors" for a further discussion of the consequences of
structural subordination.

FORM, DENOMINATIONS AND EXCHANGE

    Debt securities of a series may be issuable solely as registered securities,
solely as bearer securities or as both registered securities and bearer
securities. Registered securities will be issuable in denominations of

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US$1,000 and integral multiples of US$1,000 and bearer securities will be
issuable in denominations of US$5,000 or, in each case, in such other
denominations as may be set out in the terms of the debt securities of any
particular series. (Section 3.2) The Indenture also provides that debt
securities of a series may be issuable in global form. (Section 3.1) Unless
otherwise indicated in the Prospectus Supplement, bearer securities will have
interest coupons attached. (Section 2.1)

    Registered securities of any series will be exchangeable for other
registered securities of the same series and of a like aggregate principal
amount and tenor of different authorized denominations. If (but only if)
provided in the Prospectus Supplement, bearer securities (with all unmatured
coupons, except as provided below, and all matured coupons in default) of any
series may be exchanged for registered securities of the same series of any
authorized denominations and of a like aggregate principal amount and tenor. In
such event, bearer securities surrendered in a permitted exchange for registered
securities between a regular record date or a special record date and the
relevant date for payment of interest shall be surrendered without the coupon
relating to such date for payment of interest, and interest will not be payable
on such date for payment of interest in respect of the registered security
issued in exchange for such bearer security, but will be payable only to the
holder of such coupon when due in accordance with the terms of the Indenture.
Unless otherwise specified in the Prospectus Supplement, bearer securities will
not be issued in exchange for registered securities. (Section 3.5)

    The applicable Prospectus Supplement may indicate the places to register a
transfer of debt securities. Except for certain restrictions set forth in the
Indenture, no service charge will be made for any registration of transfer or
exchange of the debt securities, but the Corporation may, in certain instances,
require a sum sufficient to cover any tax or other governmental charges payable
in connection with these transactions. (Section 3.5)

    The Corporation shall not be required to: (i) issue, register the transfer
of or exchange debt securities of any series during a period beginning at the
opening of business 15 days before any selection of debt securities of that
series to be redeemed and ending at the close of business on (A) if debt
securities of the series are issuable only as registered securities, the day of
mailing of the relevant notice of redemption and (B) if debt securities of the
series are issuable as bearer securities, the day of the first publication of
the relevant notice of redemption or, if debt securities of the series are also
issuable as registered securities and there is no publication, the mailing of
the relevant notice of redemption; (ii) register the transfer of or exchange any
registered security, or portion thereof, called for redemption, except the
unredeemed portion of any registered security being redeemed in part;
(iii) exchange any bearer security selected for redemption, except that, to the
extent provided with respect to such bearer security, such bearer security may
be exchanged for a registered security of that series and like tenor, provided
that such registered security shall be immediately surrendered for redemption
with written instruction for payment consistent with the provisions of the
Indenture; or (iv) issue, register the transfer of or exchange any debt
securities which have been surrendered for repayment at the option of the
holder, except the portion, if any, thereof not to be so repaid. (Section 3.5)

PAYMENT


    Unless otherwise indicated in the applicable Prospectus Supplement, payment
of principal of and premium, if any, and interest, if any, on debt securities
(other than global securities) will be made at the office or agency of the
Trustee, at 15 Broad Street, New York, New York 10286, or we can pay principal,
interest and any premium by (i) check mailed or delivered to the address of the
person entitled at the address appearing in the security register of the Trustee
or (ii) wire transfer to an account located in the United States of the person
entitled to receive payments. (Sections 3.7, 10.1 and 10.2)


    Unless otherwise indicated in the applicable Prospectus Supplement, payment
of any interest will be made to the persons in whose name the debt securities
are registered at the close of business on the day or days specified by us.
(Section 3.7)

GLOBAL SECURITIES

    The registered debt securities of a series may be issued in whole or in part
in global form (a "Global Security") and will be registered in the name of and
be deposited with a depository (the "Depositary"), or its nominee, each of which
will be identified in the Prospectus Supplement. (Section 3.1) Unless and until

                                       29
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exchanged, in whole or in part, for debt securities in definitive registered
form, a Global Security, may not be transferred except as a whole by the
Depositary for such Global Security to a nominee of the Depositary, by a nominee
of the Depositary to the Depositary or another nominee of the Depositary or by
the Depositary or any such nominee to a successor of the Depositary or a nominee
of the successor. (Section 3.5)

    The specific terms of the depository arrangement with respect to any portion
of a particular series of debt securities to be represented by a Global Security
will be described in the Prospectus Supplement relating to such series. The
Corporation anticipates that the following provisions will apply to all
depository arrangements.

    Upon the issuance of a Global Security, the Depositary therefor or its
nominee will credit, on its book entry and registration system, the respective
principal amounts of the debt securities represented by the Global Security to
the accounts of such persons having accounts with such Depositary or its nominee
("participants"). Such accounts shall be designated by the underwriters, dealers
or agents participating in the distribution of the debt securities or by
TransAlta if such debt securities are offered and sold directly by the
Corporation. Ownership of beneficial interests in a Global Security will be
limited to participants or persons that may hold beneficial interests through
participants. Ownership of beneficial interests in a Global Security will be
shown on, and the transfer of that ownership will be effected only through,
records maintained by the Depositary therefor or its nominee (with respect to
interests of participants) or by participants or persons that hold through
participants (with respect to interests of persons other than participants). The
laws of some states in the United States may require that certain purchasers of
securities take physical delivery of such securities in definitive form.

    So long as the Depositary for a Global Security or its nominee is the
registered owner of the Global Security, such Depositary or such nominee, as the
case may be, will be considered the sole owner or holder of the debt securities
represented by the Global Security for all purposes under the Indenture. Except
as provided below, owners of beneficial interests in a Global Security will not
be entitled to have debt securities of the series represented by the Global
Security registered in their names, will not receive or be entitled to receive
physical delivery of debt securities of such series in definitive form and will
not be considered the owners or holders thereof under the Indenture.

    Any payments of principal, premium, if any, and interest on Global
Securities registered in the name of a Depositary or its nominee will be made to
the Depositary or its nominee, as the case may be, as the registered owner of
the Global Security representing such debt securities. None of TransAlta, the
Trustee or any paying agent for debt securities represented by the Global
Securities will have any responsibility or liability for any aspect of the
records relating to or payments made on account of beneficial ownership
interests of the Global Security or for maintaining, supervising or reviewing
any records relating to such beneficial ownership interests.

    The Corporation expects that the Depositary for a Global Security or its
nominee, upon receipt of any payment of principal, premium or interest, will
credit participants' accounts with payments in amounts proportionate to their
respective beneficial interests in the principal amount of the Global Security
as shown on the records of such Depositary or its nominee. The Corporation also
expects that payments by participants to owners of beneficial interests in a
Global Security held through such participants will be governed by standing
instructions and customary practices, as is now the case with securities held
for the accounts of customers registered in "street name", and will be the
responsibility of such participants.

    If a Depositary for a Global Security representing a particular series of
debt securities is at any time unwilling or unable or no longer qualified to
continue as depository and a successor depository is not appointed by TransAlta
within 90 days, the Corporation will issue debt securities of such series in
definitive form in exchange for a Global Security representing such series of
debt securities. Further, if an Event of Default under the Indenture occurs and
is continuing, debt securities of a series in definitive form will be printed
and delivered. In addition, the Corporation may at any time and in its sole
discretion determine not to have debt securities of a series represented by a
Global Security and, in such event, will issue debt securities of a series in
definitive form in exchange for all of the Global Securities representing the
series of debt securities. (Section 3.5)

                                       30
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DEFINITIONS

    The Indenture contains, among others, definitions substantially to the
following effect:

"ATTRIBUTABLE AMOUNT" means with respect to any sale and leaseback transaction
(as defined herein), as at the time of determination, the present value
(discounted at the rate of interest set forth or implicit in the terms of such
lease, compounded annually) of the total obligations of the lessee for rental
payments during the remaining term of the lease included in such sale and
leaseback transaction.

"CONSOLIDATED NET TANGIBLE ASSETS" means all consolidated assets of the
Corporation as shown on the most recent audited consolidated balance sheet of
the Corporation, less the aggregate of the following amounts reflected upon such
balance sheet:

    (a) all goodwill, deferred assets, trademarks, copyrights and other similar
       intangible assets;

    (b) to the extent not already deducted in computing such assets and without
       duplication, depreciation, depletion, amortization, reserves and any
       other account which reflects a decrease in the value of an asset or a
       periodic allocation of the cost of an asset;

    (c) minority interests;

    (d) current liabilities; and


    (e) assets created, developed, constructed or acquired with or in respect of
       which Non-Recourse Debt has been incurred, and any and all receivables,
       inventory, equipment, chattel paper, intangibles and other rights or
       collateral arising from or connected with those assets (including the
       shares or other ownership interests of a single purpose entity which
       holds only such assets and other rights and collateral arising from or
       connected therewith) and to which recourse of the lender of such
       Non-Recourse Debt is limited.


"CONSOLIDATED SHAREHOLDERS' EQUITY" means, without duplication, the aggregate
amount of shareholders' equity (including, without limitation, common share
capital, preferred share capital, contributed surplus and retained earnings) of
the Corporation as shown on the most recent audited consolidated balance sheet
of the Corporation, adjusted by the amount by which common share capital,
preferred share capital and contributed surplus has been increased or decreased
(as the case may be) from the date of such balance sheet to the relevant date of
determination, in accordance with Generally Accepted Accounting Principles,
together with the aggregate principal amount of obligations of the Corporation
in respect of Preferred Securities.

"FINANCIAL INSTRUMENT OBLIGATIONS" means obligations arising under:

    (a) any interest swap agreement, forward rate agreement, floor, cap or
       collar agreement, futures or options, insurance or other similar
       agreement or arrangement, or any combination thereof, entered into or
       guaranteed by the Corporation where the subject matter of the same is
       interest rates or the price, value, or amount payable thereunder is
       dependent or based upon the interest rates or fluctuations in interest
       rates in effect from time to time (but, for certainty, shall exclude
       conventional floating rate debt);

    (b) any currency swap agreement, cross-currency agreement, forward
       agreement, floor, cap or collar agreement, futures or options, insurance
       or other similar agreement or arrangement, or any combination thereof,
       entered into or guaranteed by the Corporation where the subject matter of
       the same is currency exchange rates or the price, value or amount payable
       thereunder is dependent or based upon currency exchange rates or
       fluctuations in currency exchange rates in effect from time to time; and

    (c) any agreement for the making or taking of any commodity (including
       natural gas, oil or electricity), any commodity swap agreement, floor,
       cap or collar agreement or commodity future or option or other similar
       agreements or arrangements, or any combination thereof, entered into or
       guaranteed by the Corporation where the subject matter of the same is any
       commodity or the price, value or amount payable thereunder is dependent
       or based upon the price of any commodity or fluctuations in the price of
       any commodity;

                                       31
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to the extent of the net amount due or accruing due by the Corporation
thereunder (determined by marking-to-market the same in accordance with
their terms).

"GENERALLY ACCEPTED ACCOUNTING PRINCIPLES" means generally accepted accounting
principles which are in effect from time to time in Canada.

"INDEBTEDNESS" means all items of indebtedness in respect of any amounts
borrowed (including obligations with respect to bankers' acceptances and
contingent reimbursement obligations relating to letters of credit and other
financial instruments) and all Purchase Money Obligations which, in accordance
with Generally Accepted Accounting Principles, would be recorded in the
financial statements as at the date as of which Indebtedness is to be
determined, and in any event including, without duplication:

    (a) obligations secured by any Security Interest existing on property owned
       subject to such Security Interest, whether or not the obligations secured
       thereby shall have been assumed; and

    (b) guarantees, indemnities, endorsements (other than endorsements for
       collection in the ordinary course of business) or other contingent
       liabilities in respect of obligations of another person for indebtedness
       of that other person in respect of any amounts borrowed by them.

"MATERIAL SUBSIDIARY" means, at any time, a Subsidiary:

    (a) the total assets of which represent more than 10% of the total assets of
       the Corporation determined on a consolidated basis as shown in the most
       recent audited consolidated balance sheet of the Corporation; or

    (b) the total revenues of which represent more than 10% of the total
       revenues of the Corporation determined on a consolidated basis as shown
       in the consolidated income statement of the Corporation for the four most
       recent fiscal quarters of the Corporation.


"NON-RECOURSE DEBT" means any Indebtedness incurred to finance the creation,
development, construction or acquisition of assets and any increases in or
extensions, renewals or refundings of any such Indebtedness, provided that the
recourse of the lender thereof or any agent, trustee, receiver or other person
acting on behalf of the lender in respect of such Indebtedness or any judgment
in respect thereof is limited in all circumstances (other than in respect of
false or misleading representations or warranties and customary indemnities
provided with respect to such financings) to the assets created, developed,
constructed or acquired in respect of which such Indebtedness has been incurred
and to any receivables, inventory, equipment, chattel paper, intangibles and
other rights or collateral arising from or connected with the assets so created,
developed, constructed or acquired, (including the shares or other ownership
interests of a single purpose entity which holds only such assets and other
rights and collateral arising from or connected therewith) and to which the
lender has recourse.


"PERMITTED ENCUMBRANCE" means any of the following:

    (a) any Security Interest existing as of the date of the first issuance by
       the Corporation of debt securities issued pursuant to the Indenture, or
       arising thereafter pursuant to contractual commitments entered into prior
       to such issuance;

    (b) any Security Interest created, incurred or assumed to secure any
       Purchase Money Obligation;

    (c) any Security Interest created, incurred or assumed to secure any
       Non-Recourse Debt;

    (d) any Security Interest in favor of any Wholly-owned Subsidiary;

    (e) any Security Interest on property of a corporation or its Subsidiaries
       which Security Interest exists at the time such corporation is merged
       into, or amalgamated or consolidated with the Corporation or such
       property is otherwise directly or indirectly acquired by the Corporation,
       other than a Security Interest incurred in contemplation of such merger,
       amalgamation, consolidation or acquisition;

    (f) any Security Interest securing any Indebtedness to any bank or banks or
       other lending institution or institutions incurred in the ordinary course
       of business and for the purpose of carrying on the same, repayable on
       demand or maturing within 12 months of the date when such Indebtedness is
       incurred or the date of any renewal or extension thereof;

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    (g) any Security Interest on or against cash or marketable debt securities
       pledged to secure Financial Instrument Obligations;

    (h) certain Security Interests in respect of liens or other encumbrances,
       not related to the borrowing of money, incurred or arising by operation
       of law or in the ordinary course of business;

    (i) any extension, renewal, alteration or replacement (or successive
       extensions, renewals, alterations or replacements) in whole or in part,
       of any Security Interest referred to in the foregoing clauses (a)
       through (h) inclusive, provided the extension, renewal, alteration or
       replacement of such Security Interest is limited to all or any part of
       the same property that secured the Security Interest extended, renewed,
       altered or replaced (plus improvements on such property) and the
       principal amount of the Indebtedness secured thereby is not
       increased; and


    (j) any other Security Interest if the aggregate amount of Indebtedness
       secured pursuant to this clause (j) (together with the Attributable
       Amount of any sale and leaseback) does not exceed 20% of Consolidated Net
       Tangible Assets.


"PREFERRED SECURITIES" means securities which on the date of issue thereof by
a person:

    (a) have a term to maturity of more than 30 years;

    (b) rank subordinate to the unsecured and unsubordinated Indebtedness of
       such person outstanding on such date;

    (c) entitle such person to defer the payment of interest thereon for more
       than four years without thereby causing an event of default in respect of
       such securities to occur; and

    (d) entitle such person to satisfy the obligation to make payments of
       deferred interest thereon from the proceeds of the issuance of
       its shares.

"PURCHASE MONEY OBLIGATION" means any monetary obligation created or assumed as
part of the purchase price of real or tangible personal property, whether or not
secured, any extensions, renewals, alterations or replacements of any such
obligation, provided that the principal amount of such obligation outstanding on
the date of such extension, renewal, alteration or replacement is not increased
and further provided that any security given in respect of such obligation shall
not extend to any property other than the property acquired in connection with
which such obligation was created or assumed and fixed improvements, if any,
erected or constructed thereon.


"SECURITY INTEREST" means any mortgage, charge, pledge, lien, encumbrance,
assignment by way of security, title retention agreement or other security
interest whatsoever, howsoever created or arising, whether absolute or
contingent, fixed or floating, perfected or not, which secures payment or
performance of an obligation.


"SUBSIDIARY" means, in relation to a person:

    (a) any corporation of which at least a majority of the outstanding shares
       having by the terms thereof ordinary voting power to elect a majority of
       the board of directors of such corporation (irrespective of whether at
       the time shares of any other class or classes of such corporation might
       have voting power by reason of the happening of any contingency, unless
       the contingency has occurred and then only for as long as it continues)
       is at the time directly, indirectly or beneficially owned or controlled
       by the person or one or more of its Subsidiaries, or the person and one
       or more of its Subsidiaries;

    (b) any partnership of which the person or one or more of its Subsidiaries,
       or the person and one or more of its Subsidiaries: (i) directly,
       indirectly or beneficially own or control more than 50% of the income,
       capital, beneficial or ownership interests (however designated) thereof;
       and (ii) is a general partner, in the case of a limited partnership, or
       is a partner that has authority to bind the partnership, in all other
       cases; or


    (c) any other person of which at least a majority of the income, capital,
       beneficial or ownership interests (however designated) are at the time
       directly, indirectly or beneficially owned or controlled by the
       first-mentioned person or one or more of its Subsidiaries, or the
       first-mentioned person and one or more of its Subsidiaries.


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"WHOLLY-OWNED SUBSIDIARY" means any Subsidiary that the Corporation directly or
indirectly beneficially owns 100% of the outstanding shares having by the terms
thereof ordinary voting power to elect a majority of the board of directors of
such Subsidiary or owns, directly or indirectly, 100% of the income, capital,
beneficial or ownership interests (however designated) thereof.

COVENANTS

    The Indenture contains covenants substantially to the following effect:

NEGATIVE PLEDGE


    So long as any debt securities remain outstanding the Corporation and its
Subsidiaries will not create, assume or otherwise have outstanding any Security
Interest, except for Permitted Encumbrances, on or over its or their respective
assets (present or future) in respect of any Indebtedness of any person unless,
in the opinion of legal counsel to the Corporation or the Trustee, the
obligations of the Corporation in respect of all debt securities then
outstanding shall be secured equally and ratably therewith. (Section 10.12)


RESTRICTION ON SALES AND LEASEBACKS

    The Corporation will not, and will not permit any Subsidiary to, enter into
any sale and leaseback transaction unless the Corporation and its Subsidiaries
comply with this restrictive covenant. A "sale and leaseback transaction"
generally is an arrangement between the Corporation or any Subsidiary and a
bank, insurance company or other lender or investor where the Corporation or any
Subsidiary lease real or personal property which was or will be sold by the
Corporation or any Subsidiary to that lender or investor. The Corporation can
comply with this restrictive covenant if it meets either of the
following conditions:

    (a) the sale and leaseback transaction is entered into prior to,
       concurrently with or within 270 days after the acquisition, the
       completion of construction (including any improvements on an existing
       property) or the commencement of commercial operations of the
       property; or


    (b) the Corporation or its Subsidiaries could otherwise grant a Security
       Interest on the property as a Permitted Encumbrance described in
       "-- Negative Pledge". (Section 10.10)


MERGERS, CONSOLIDATIONS, AMALGAMATIONS AND SALE OF ASSETS

    The Corporation will not enter into any transaction whereby all or
substantially all of its undertaking, property and assets would become the
property of any other person (the "Successor"), whether by reorganization,
consolidation, amalgamation, arrangement, merger, transfer, sale, or
otherwise, unless:

    (a) the Successor expressly assumes all of the covenants and obligations of
       the Corporation under the Indenture and the transaction otherwise meets
       of the requirements of the Indenture;


    (b) the entity formed by or continuing from such consolidation or
       amalgamation or into which the Corporation is merged or with which the
       Corporation enters into such arrangement or the person which acquires or
       leases all or substantially all of the Corporation's properties and
       assets is organized and existing under the laws of the United States, any
       state thereof or the District of Columbia or the laws of Canada or any
       province thereof; and



    (c) immediately before and after giving effect to such transaction, no event
       of default, and no event which, after notice or lapse of time or both,
       would become an event of default, shall have happened and be continuing.
       (Section 8.1)


    If, as a result of any such transaction, any of the properties or assets of
the Corporation or its Subsidiaries become subject to a Security Interest, then,
unless such Security Interest could be created pursuant to the Indenture
provisions described under "Negative Pledge" above without equally and rateably
securing debt securities, the Corporation, simultaneously with or prior to such
transaction, will cause any debt securities of the Corporation then outstanding
to be secured equally and ratably with or prior to the Indebtedness secured by
such Security Interest. (Section 8.4)

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    In addition to the above conditions, such transaction will, to the
satisfaction of the Trustee, substantially preserve and not impair any of the
rights and powers of the Trustee or of the security holders. Also, no condition
or event will exist as to the Corporation (at the time of such transaction) or
the Successor (immediately after such transaction) and after giving full effect
thereto or immediately after the Successor will become liable to pay the
principal monies, premium, if any, interest and other monies due or which may
become due hereunder, which constitutes or would constitute and Event of Default
under the Indenture.

PAYMENT OF ADDITIONAL AMOUNTS


    Unless otherwise specified in an applicable Prospectus Supplement, TransAlta
will, subject to the exceptions and limitations set forth below, pay to the
holder of any debt security who is a non-resident of Canada under the INCOME
TAX ACT (Canada) such additional amounts as may be necessary so that every net
payment on such debt security, after deduction or withholding by TransAlta or
any of its paying agents for or on account of any present or future tax,
assessment or other governmental charge (including penalties, interest and other
liabilities related thereto) imposed by the government of Canada (or any
political subdivision or taxing authority thereof or therein) (collectively,
"Canadian Taxes") upon or as a result of such payment, will not be less than the
amount provided in such debt security or in such coupon to be then due and
payable (and TransAlta will remit the full amount withheld to the relevant
authority in accordance with applicable law). However, TransAlta will not be
required to make any payment of additional amounts:


    (a) to any person in respect of whom such taxes are required to be withheld
       or deducted as a result of such person not dealing at arm's length with
       TransAlta (within the meaning of the INCOME TAX ACT (Canada));

    (b) to any person by reason of such person being connected with Canada
       (otherwise than merely by holding or ownership of any series of debt
       securities or receiving any payments or exercising any rights
       thereunder), including without limitation a non-resident insurer who
       carries on an insurance business in Canada and in a country other
       than Canada;

    (c) for or on account of any tax, assessment or other governmental charge
       which would not have been so imposed but for: (i) the presentation by the
       holder of such debt security or coupon for payment on a date more than
       30 days after the date on which such payment became due and payable or
       the date on which payment thereof is duly provided for, whichever occurs
       later; or (ii) the holder's failure to comply with any certification,
       identification, information, documentation or other reporting
       requirements if compliance is required by law, regulation, administrative
       practice or an applicable treaty as a precondition to exemption from or a
       reduction in the rate of deduction or withholding of, any such taxes,
       assessment or charge;

    (d) for or on account of any estate, inheritance, gift, sales, transfer,
       personal property tax or any similar tax, assessment or other
       governmental charge;

    (e) for or on account of any tax, assessment or other governmental charge
       required to be withheld by any paying agent from any payment to a person
       on a debt security if such payment can be made to such person without
       such withholding by at least one other paying agent the identity of which
       is provided to such person;

    (f) for or on account of any tax, assessment or other governmental charge
       which is payable otherwise than by withholding from a payment on a debt
       security; or

    (g) for any combination of items (a), (b), (c), (d), (e) and (f);

nor will additional amounts be paid with respect to any payment on a debt
security to a holder who is a fiduciary or partnership or other than the sole
beneficial owner of such payment to the extent such payment would be required by
the laws of Canada (or any political subdivision thereof) to be included in the
income for Canadian federal income tax purposes of a beneficiary or settlor with
respect to such fiduciary or a member of such partnership or a beneficial owner
who would not have been entitled to payment of the additional amounts had such
beneficiary, settlor, member or beneficial owner been the holder of such debt
security. (Section 10.5)

                                       35
<Page>
    The Corporation will furnish to the holders of the debt securities, within
30 days after the date of the payment of any Canadian Taxes is due under
applicable law, certified copies of tax receipts or other documents evidencing
such payment.

    Wherever in the Indenture there is mentioned, in any context, the payment of
principal (and premium, if any), interest or any other amount payable under or
with respect to a debt security, such mention shall be deemed to include mention
of the payment of additional amounts to the extent that, in such context
additional amounts are, were or would be payable in respect thereof.
(Section 10.5)

TAX REDEMPTION

    If and to the extent specified in an applicable Prospectus Supplement, the
debt securities of a series will be subject to redemption at any time, in whole
but not in part, at a redemption price equal to the principal amount thereof
together with accrued and unpaid interest to the date fixed for redemption, upon
the giving of a notice as described below, if (1) TransAlta determines that
(a) as a result of any change in or amendment to the laws (or any regulations or
rulings promulgated thereunder) of Canada or of any political subdivision or
taxing authority thereof or therein affecting taxation, or any change in
official position regarding application or interpretation of such laws,
regulations or rulings (including a holding by a court of competent
jurisdiction), which change or amendment is announced or becomes effective on or
after a date specified in the applicable Prospectus Supplement if any date is so
specified, TransAlta has or will become obligated to pay, on the next succeeding
date on which interest is due, additional amounts with respect to any debt
security of such series as described under "Payment of Additional Amounts" or
(b) on or after a date specified in the applicable Prospectus Supplement, any
action has been taken by any taxing authority of, or any decision has been
rendered by a court of competent jurisdiction in, Canada or any political
subdivision or taxing authority thereof or therein, including any of those
actions specified in (a) above, whether or not such action was taken or decision
was rendered with respect to TransAlta, or any change, amendment, application or
interpretation shall be officially proposed, which, in any such case, in the
written opinion to TransAlta of legal counsel of recognized standing, will
result in TransAlta becoming obligated to pay, on the next succeeding date on
which interest is due, additional amounts with respect to any debt security of
such series and (2) in any such case, TransAlta in its business judgment
determines that such obligation cannot be avoided by the use of reasonable
measures available to TransAlta; PROVIDED HOWEVER, that (i) no such notice of
redemption may be given earlier than 60 or later than 30 days prior to the
earliest date on which TransAlta would be obligated to pay such additional
amounts were a payment in respect of the debt securities then due, and (ii) at
the time such notice of redemption is given, such obligation to pay such
additional amounts remains in effect. (Section 11.8)

    In the event that TransAlta elects to redeem the debt securities of such
series pursuant to the provisions set forth in the preceding paragraph,
TransAlta shall deliver to the Trustee a certificate, signed by an authorized
officer, stating that TransAlta is entitled to redeem the debt securities of
such series pursuant to their terms. (Section 11.2)

REDEMPTION

    If and to the extent specified in an applicable Prospectus Supplement, the
debt securities of a series will be subject to redemption at the time or times
specified therein, at a redemption price equal to the principal amount thereof
together with accrued and unpaid interest to the date fixed for redemption, upon
the giving of a notice. Notice of redemption of the debt securities of such
series will be given once not more than 60 nor less than 30 days prior to the
date fixed for redemption and will specify the date fixed for redemption.
(Section 11.4)

PROVISION OF FINANCIAL INFORMATION

    TransAlta will file with the Trustee, within 15 days after it files them
with the SEC, copies of its annual report and of the information, documents and
other reports (or copies of such portions of any of the foregoing as the SEC may
by rules and regulations prescribe) which TransAlta is required to file with the
SEC pursuant to Section 13 or 15(d) of the U.S. Exchange Act. Notwithstanding
that TransAlta may not be required to remain subject to the reporting
requirements of Section 13 or 15(d) of the U.S. Exchange Act or otherwise report
on an annual and quarterly basis on forms provided for such annual and quarterly
reporting pursuant to rules and

                                       36
<Page>
regulations promulgated by the SEC, TransAlta will continue to provide the
Trustee (a) within 140 days after the end of each fiscal year, the information
required to be contained in annual reports on Form 20-F or Form 40-F as
applicable (or any successor form); and (b) within 60 days after the end of each
of the first three fiscal quarters of each fiscal year, the information required
to be contained in reports on Form 6-K (or any successor form), which,
regardless of applicable requirements shall, at a minimum, consist of such
information required to be provided in quarterly reports under the laws of
Canada or any province thereof to security holders of a corporation with
securities listed on the TSX, whether or not TransAlta has any of its securities
listed on such exchange. Such information will be prepared in accordance with
Canadian disclosure requirements and Canadian GAAP. (Section 7.5)

EVENTS OF DEFAULT

    Unless otherwise specified in the Prospectus Supplement relating to a
particular series of debt securities, the following events are defined in the
Indenture as "Events of Default" with respect to debt securities of any series:
(a) the failure of the Corporation to pay when due the principal of or premium
(if any) on any debt securities; (b) the failure of the Corporation, continuing
for 30 days, to pay any interest due on any debt securities; (c) the breach or
violation of any covenant or condition (other than as referred to in (a) and
(b) above), which continues for a period of 60 days after notice from the
Trustee or from holders of at least 25% in principal amount of all outstanding
debt securities of any series affected thereby (or such longer period as may be
agreed to by the Trustee); (d) the failure of the Corporation or any Subsidiary
to pay when due (after giving effect to any applicable grace periods) any amount
owing in respect of any Indebtedness other than Non-Recourse Debt or the
Corporation or any Subsidiary otherwise defaults in connection with such
Indebtedness, and if such Indebtedness has not matured it shall have been
accelerated, provided that the aggregate principal amount of such Indebtedness
is in excess of the greater of US$75 million and 3% of Consolidated
Shareholders' Equity; (e) the taking or entry of certain judgments or decrees
against the Corporation or any Material Subsidiary for the payment of money in
excess of the greater of US$75 million and 3% of Consolidated Shareholders'
Equity, in the aggregate, if the Corporation or any such Material Subsidiary, as
the case may be, fails to file an appeal or, if the Corporation or such Material
Subsidiary, as the case may be does file an appeal, that judgment or decree is
not and does not remain vacated, discharged or stayed as provided in the
Indenture; (f) certain events of bankruptcy, insolvency or reorganization
involving the Corporation or a Material Subsidiary; or (g) any other Event of
Default provided with respect to debt securities of that series.

    If an Event of Default occurs and is continuing with respect to any series
of debt securities, then and in every such case the Trustee or the holders of at
least 25% in aggregate principal amount of the outstanding debt securities of
such affected series may, subject to any subordination provisions thereof,
declare the entire principal amount (or, if the debt securities of that series
are original issue discount debt securities, such portion of the principal
amount as may be specified in the terms of that series) of all debt securities
of such series and all interest thereon to be immediately due and payable.
However, at any time after a declaration of acceleration with respect to any
series of debt securities has been made, but before a judgment or decree for
payment of the money due has been obtained, the holders of a majority in
principal amount of the outstanding debt securities of that series, by written
notice to the Corporation and the Trustee under certain circumstances (which
include payment or deposit with the Trustee of outstanding principal, premium
and interest, unless the Prospectus Supplement applicable to an issue of debt
securities otherwise provides), may rescind and annul such acceleration.
(Section 5.2)

    Reference is made to the Prospectus Supplement relating to each series of
debt securities which are original issue discount securities for the particular
provisions relating to acceleration of the maturity of a portion of the
principal amount of such original issue discount securities upon the occurrence
of any Event of Default and the continuation hereof.

    The Indenture provides that, subject to the duty of the Trustee during
default to act with the required standard of care, the Trustee shall be under no
obligation to exercise any of its rights and powers under the Indenture at the
request or direction of any of the holders, unless such holders shall have
offered to the Trustee reasonable indemnity. (Section 6.2) Subject to such
provisions for indemnification of the Trustee and certain other limitations set
forth in the Indenture, the holders of a majority in principal amount of the
outstanding debt

                                       37
<Page>
securities of all series affected by an Event of Default shall have the right to
direct the time, method and place of conducting any proceeding for any remedy
available to the Trustee, or exercising any trust or power conferred on the
Trustee, with respect to the debt securities of all series affected by such
Event of Default. (Section 5.12)

    No holder of a debt security of any series will have any right to institute
any proceeding with respect to the Indenture, or for the appointment of a
receiver or a Trustee, or for any other remedy thereunder, unless (a) such
holder has previously given to the Trustee written notice of a continuing Event
of Default with respect to the debt securities of such series affected by such
Event of Default, (b) the holders of at least 25% in aggregate principal amount
of the outstanding debt securities of such series affected by such Event of
Default have made written request, and such holder or holders have offered
reasonable indemnity, to the Trustee to institute such proceeding as Trustee,
and (c) the Trustee has failed to institute such proceeding, and has not
received from the holders of a majority in aggregate principal amount of the
outstanding debt securities of such series affected by such Event of Default a
direction inconsistent with such request, within 60 days after such notice,
request and offer. (Section 5.7) However, such limitations do not apply to a
suit instituted by the holder of a debt security for the enforcement of payment
of the principal of or any premium or interest on such debt security on or after
the applicable due date specified in such debt security. (Section 5.8)

    The Corporation will be required to furnish to the Trustee annually a
statement by certain of its officers as to whether or not the Corporation, to
the best of their knowledge, is in compliance with all conditions and covenants
of the Indenture and, if not, specifying all such known defaults.
(Section 10.4)

MODIFICATION AND WAIVER

    Modifications and amendments of the Indenture may be made by the Corporation
and the Trustee with the consent of the holders of a majority in principal
amount of the outstanding debt securities of each series issued under the
Indenture affected by such modification or amendment; PROVIDED, HOWEVER, that no
such modification or amendment may, without the consent of the holder of each
outstanding debt security of such affected series: (1) change the stated
maturity of the principal of, or any instalment of interest, if any, on any debt
security; (2) reduce the principal amount of, or the premium, if any, or the
rate of interest, if any, on any debt security; (3) change the place of payment;
(4) change the currency or currency unit of payment of principal of (or premium,
if any) or interest, if any, on any debt security; (5) impair the right to
institute suit for the enforcement of any payment on or with respect to any debt
security; (6) adversely affect any right to convert or exchange any debt
security; (7) reduce the percentage of principal amount of outstanding debt
securities of such series, the consent of the holders of which is required for
modification or amendment of the applicable Indenture or for waiver of
compliance with certain provisions of the Indenture or for waiver of certain
defaults; (8) reduce the voting or quorum requirements relating to meetings of
holders of debt securities; or (9) modify any provisions of the Indenture
relating to the modification and amendment of the Indenture or the waiver of
past defaults or covenants except as otherwise specified in the Indenture.
(Section 9.2) In addition, any amendment to, or waiver of, the provisions of the
Indenture relating to subordination that adversely affects the rights of the
holders of debt securities will require the consent of holders of at least 75%
in aggregate principal amount of such debt securities then outstanding.


    The holders of a majority in principal amount of the outstanding debt
securities of any series may on behalf of the holders of all debt securities of
that series waive, insofar as that series is concerned, compliance by the
Corporation with certain restrictive provisions of the Indenture.
(Section 10.13) The holders of a majority in principal amount of outstanding
debt securities of any series may waive any past default under the Indenture
with respect to that series, except a default in the payment of the principal of
(or premium, if any) and interest, if any, on any debt security of that series
or in respect of a provision which under the Indenture cannot be modified or
amended without the consent of the holder of each outstanding debt security of
that series. (Section 5.13) The Indenture or the debt securities may be amended
or supplemented, without the consent of any holder of debt securities, to cure
any ambiguity or inconsistency or to make any change that does not have an
adverse effect on the rights of any holder of debt securities. (Section 9.1)


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DEFEASANCE


    The Indenture provides that, at its option, TransAlta will be discharged
from any and all obligations in respect of the outstanding debt securities of
any series upon irrevocable deposit with the Trustee, in trust, of money and/or
government securities which will provide money in an amount sufficient in the
opinion of a nationally recognized firm of independent chartered accountants to
pay the principal of and premium, if any, and each instalment of interest, if
any, on the outstanding debt securities of such series ("Defeasance") (except
with respect to the authentication, transfer, exchange or replacement of debt
securities or the maintenance of a place of payment and certain other
obligations set forth in the Indenture). Such trust may only be established if
among other things (1) TransAlta has delivered to the Trustee an opinion of
counsel in the United States stating that (a) TransAlta has received from, or
there has been published by, the Internal Revenue Service a ruling, or
(b) since the date of execution of the Indenture, there has been a change in the
applicable United States federal income tax law, in either case to the effect
that the holders of the outstanding debt securities of such series will not
recognize income, gain or loss for United States federal income tax purposes as
a result of such Defeasance and will be subject to United States federal income
tax on the same amounts, in the same manner and at the same times as would have
been the case if such Defeasance had not occurred; (2) TransAlta has delivered
to the Trustee an opinion of counsel in Canada or a ruling from the Canada
Customs and Revenue Agency ("CCRA") to the effect that the holders of such
outstanding debt securities of such series will not recognize income, gain or
loss for Canadian federal, provincial or territorial income or other tax
purposes as a result of such Defeasance and will be subject to Canadian federal
or provincial income and other tax on the same amounts, in the same manner and
at the same times as would have been the case had such Defeasance not occurred
(and for the purposes of such opinion, such Canadian counsel shall assume that
holders of the outstanding debt securities of such series include holders who
are not resident in Canada); (3) no Event of Default or event that, with the
passing of time or the giving of notice, or both, shall constitute an Event of
Default shall have occurred and be continuing on the date of such deposit;
(4) TransAlta is not an "insolvent person" within the meaning of the CANADIAN
BANKRUPTCY AND INSOLVENCY ACT; (5) TransAlta has delivered to the Trustee an
opinion of counsel to the effect that such deposit shall not cause the Trustee
or the trust so created to be subject to the United States INVESTMENT COMPANY
ACT OF 1940, as amended; and (6) other customary conditions precedent are
satisfied. TransAlta may exercise its Defeasance option notwithstanding its
prior exercise of its Covenant Defeasance option described in the following
paragraph if TransAlta meets the conditions described in the preceding sentence
at the time TransAlta exercises the Defeasance option.



    The Indenture provides that, at its option, unless and until TransAlta has
exercised its Defeasance option described in the preceding paragraph, TransAlta
may omit to comply with covenants, including the covenants described above under
the heading "Covenants", and such omission shall not be deemed to be an Event of
Default under the Indenture and the outstanding debt securities upon irrevocable
deposit with the Trustee, in trust, of money and/or government securities which
will provide money in an amount sufficient in the opinion of a nationally
recognized firm of independent chartered accountants to pay the principal of and
premium, if any, and each instalment of interest, if any, on the outstanding
debt securities ("Covenant Defeasance"). If TransAlta exercises its Covenant
Defeasance option, the obligations under the Indenture other than with respect
to such covenants and the Events of Default other than with respect to such
covenants shall remain in full force and effect. Such trust may only be
established if, among other things, (1) TransAlta has delivered to the Trustee
an opinion of counsel in the United States to the effect that the holders of the
outstanding debt securities will not recognize income, gain or loss for United
States federal income tax purposes as a result of such Covenant Defeasance and
will be subject to United States federal income tax on the same amounts, in the
same manner and at the same times as would have been the case if such Covenant
Defeasance had not occurred; (2) TransAlta has delivered to the Trustee an
opinion of counsel in Canada or a ruling from the CCRA to the effect that the
holders of such outstanding debt securities will not recognize income, gain or
loss for Canadian federal, provincial or territorial income or other tax
purposes as a result of such Covenant Defeasance and will be subject to Canadian
federal or provincial income and other tax on the same amounts, in the same
manner and at the same times as would have been the case had such Covenant
Defeasance not occurred (and for the purposes of such opinion, such Canadian
counsel shall assume that holders of the outstanding debt securities include
holders who are not resident in Canada); (3) no Event of Default or event that,
with the passing of time or the giving of notice, or both, shall constitute an
Event of Default shall have occurred and be continuing on the date of such
deposit; (4) TransAlta is not an "insolvent person" within the meaning of the
CANADIAN BANKRUPTCY AND


                                       39
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INSOLVENCY ACT; (5) TransAlta has delivered to the Trustee an opinion of counsel
to the effect that such deposit shall not cause the Trustee or the trust so
created to be subject to the United States INVESTMENT COMPANY ACT OF 1940, as
amended; and (6) other customary conditions precedent are satisfied.
(Article 14)


CONSENT TO JURISDICTION AND SERVICE

    Under the Indenture, TransAlta irrevocably appoints CT Corporation System,
111 Eighth Avenue, 13th Floor, New York, New York, as its authorized agent for
service of process in any suit or proceeding arising out of or relating to the
debt securities or the Indenture and for actions brought under federal or state
securities laws in any federal or state court located in the City of New York,
and irrevocably submits to such jurisdiction. (Section 1.13)

GOVERNING LAW

    The debt securities and the Indenture will be governed by and construed in
accordance with the laws of the State of New York.

                            DESCRIPTION OF WARRANTS

GENERAL

    The Corporation may issue warrants to purchase common shares, first
preferred shares, debt securities or other securities. The Corporation may issue
warrants independently or together with other securities, and warrants sold with
other securities may be attached to or separate from the other securities.
Warrants will be issued under one or more warrant agreements between the
Corporation and a warrant agent that the Corporation will name in the
Prospectus Supplement.

    Selected provisions of the warrants and the warrant agreements are
summarized below. This summary is not complete. The statements made in this
Prospectus relating to any warrant agreement and warrants to be issued
thereunder are summaries of certain anticipated provisions thereof are subject
to, and are qualified in their entirety by reference to, all provisions of the
applicable warrant agreement.

    The Prospectus Supplement will set forth the following terms relating to the
warrants being offered:

    - the designation of the warrants;

    - the aggregate number of warrants offered and the offering price;

    - the designation, number and terms of the common shares, first preferred
      shares, debt securities or other securities purchasable upon exercise of
      the warrants, and procedures that will result in the adjustment of
      those numbers;

    - the exercise price of the warrants;

    - the dates or periods during which the warrants are exercisable;

    - the designation and terms of any securities with which the warrants
      are issued;

    - if the warrants are issued as a unit with another security, the date on
      and after which the warrants and the other security will be
      separately transferable;

    - the currency or currency unit in which the exercise price is denominated;

    - any minimum or maximum amount of warrants that may be exercised at any
      one time;

    - whether such warrants will be listed on any securities exchange;

    - any terms, procedures and limitations relating to the transferability,
      exchange or exercise of the warrants; and

    - any other terms of the warrants.

                                       40
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    Warrant certificates will be exchangeable for new warrant certificates of
different denominations at the office indicated in the Prospectus Supplement.
Prior to the exercise of their warrants, holders of warrants will not have any
of the rights of holders of the securities subject to the warrants.

MODIFICATIONS

    The Corporation may amend the warrant agreements and the warrants, without
the consent of the holders of the warrants, to cure any ambiguity, to cure,
correct or supplement any defective or inconsistent provision, or in any other
manner that will not materially and adversely affect the interests of holders of
outstanding warrants. Other amendment provisions shall be as indicated in the
Prospectus Supplement.

ENFORCEABILITY

    The warrant agent will act solely as the Corporation's agent. The warrant
agent will not have any duty or responsibility if the Corporation defaults under
the warrant agreements or the warrant certificates. A warrant holder may,
without the consent of the warrant agent, enforce by appropriate legal action on
its own behalf the holder's right to exercise the holder's warrants.

                       CERTAIN INCOME TAX CONSIDERATIONS

    The applicable Prospectus Supplement will describe certain Canadian federal
income tax consequences to an investor who is a non-resident of Canada of
acquiring any Securities offered thereunder, including whether the payments of
dividends on common shares or first preferred shares or payments of principal,
premium, if any, and interest on debt securities will be subject to Canadian
non-resident withholding tax.

    The applicable Prospectus Supplement will also describe certain United
States federal income tax consequences of the acquisition, ownership and
disposition of any securities offered thereunder by an initial investor who is a
United States person (within the meaning of the United States Internal Revenue
Code), including, to the extent applicable, any such consequences relating to
debt securities payable in a currency other than the U.S. dollars, issued at an
original issue discount for United States federal income tax purposes or
containing early redemption provisions or other special items.

                              PLAN OF DISTRIBUTION

    The Corporation may sell the Securities to or through underwriters or
dealers and also may sell the Securities directly to purchasers pursuant to
applicable statutory exemptions or through agents.

    The distribution of the Securities of any series may be effected from time
to time in one or more transactions at a fixed price or prices, which may be
changed, at market prices prevailing at the time of sale, or at prices related
to such prevailing market prices to be negotiated with purchasers.

    In connection with the sale of the Securities, underwriters may receive
compensation from the Corporation or from purchasers of the Securities for whom
they may act as agents in the form of concessions or commissions. Underwriters,
dealers and agents that participate in the distribution of the Securities may be
deemed to be underwriters and any commissions received by them from the
Corporation and any profit on the resale of the Securities by them may be deemed
to be underwriting commissions under the U.S. Securities Act.

    The Prospectus Supplement relating to each series of the Securities will
also set forth the terms of the offering of the Securities, including to the
extent applicable, the initial offering price, the proceeds to the Corporation,
the underwriting concessions or commissions, and any other discounts or
concessions to be allowed or re-allowed to dealers. Underwriters with respect to
each series sold to or through underwriters will be named in the Prospectus
Supplement relating to such series.

    Under agreements which may be entered into by the Corporation, underwriters,
dealers and agents who participate in the distribution of the Securities may be
entitled to indemnification by the Corporation against certain liabilities,
including liabilities under the U.S. Securities Act.

    The Securities offered hereby have not been qualified for sale under the
securities laws of any province or territory of Canada and are not being and may
not be offered or sold in Canada in contravention of the

                                       41
<Page>
securities laws of any province or territory of Canada. Each underwriter and
each dealer participating in the distribution of any series of the Securities
must agree that it will not offer to sell, directly or indirectly, any such
Securities acquired by it in connection with such distribution, in Canada or to
residents of Canada in contravention of the securities laws of Canada or any
province or territory thereof.

    Each series of the Securities will be a new issue of securities with no
established trading market. Unless otherwise specified in a Prospectus
Supplement relating to a series of Securities, the Securities (other than common
shares) will not be listed on any securities exchange. Certain broker-dealers
may make a market in the Securities, but will not be obligated to do so and may
discontinue any market making at any time without notice. No assurance can be
given that any broker-dealer will make a market in the Securities of any series
or as to the liquidity of the trading market, if any, for the Securities of
any series.

                                  RISK FACTORS

    PROSPECTIVE PURCHASERS OF THE SECURITIES SHOULD CONSIDER CAREFULLY THE RISK
FACTORS SET FORTH BELOW AS WELL AS THE OTHER INFORMATION CONTAINED AND
INCORPORATED BY REFERENCE IN THIS PROSPECTUS AND THE APPLICABLE PROSPECTUS
SUPPLEMENT BEFORE PURCHASING THE SECURITIES OFFERED HEREBY.

    Discussions of certain risks affecting the Corporation in connection with
its business are provided on page 12 of the Annual Information Form under the
heading "Risks of Operations" and in management's discussion and analysis of
financial condition and results of operations on pages 39 to 42 of the Annual
Report of the Corporation for the fiscal year ended December 31, 2001 under the
heading "Risk Factors and Risk Management".

    A reference herein to an adverse effect or a material adverse effect on the
Corporation means such an effect on the Corporation on its business, financial
condition, results of operations, or its cash flows, as the context requires.

RISKS RELATING TO THE ELECTRICITY GENERATION MARKET

THE RULES AND REGULATIONS IN THE VARIOUS MARKETS IN WHICH THE CORPORATION
OPERATES ARE SUBJECT TO CHANGE, WHICH MAY NEGATIVELY IMPACT THE CORPORATION.

    Certain of the markets in which the Corporation operates and intends to
operate are subject to significant regulatory oversight and control. The
Corporation is not able to predict whether there will be any further changes in
the regulatory environment, including potential regulation of the rates allowed
to be charged and the capital structure of wholesale generating companies such
as the Corporation, or what the ultimate effect changing regulatory environment
will have on its business. Existing market rules and regulations may be revised
or reinterpreted and new laws and regulations may be adopted or become
applicable to the Corporation or its facilities which could have an adverse
effect on the Corporation. The Corporation cannot guarantee that it will be able
to adapt its business in a timely manner in response to any changes in the
regulatory regimes in which it operates, and such failure to adapt could have a
material adverse effect on the Corporation.

    Further market rules or regulations that could place a cap on market based
pricing could adversely impact the Corporation. Additionally, any changes in the
rules and regulations of provincial or state public utility commissions or other
regulatory bodies in the other markets in which the Corporation competes or may
compete in the future may adversely affect the Corporation.

MANY OF THE CORPORATION'S ACTIVITIES AND PROPERTIES ARE SUBJECT TO ENVIRONMENTAL
REQUIREMENTS AND CHANGES IN, OR LIABILITIES UNDER, THESE REQUIREMENTS MAY
ADVERSELY AFFECT THE CORPORATION.

    The Corporation's operations are subject to extensive federal, provincial,
state and local environmental regulation. To comply with these legal
requirements, the Corporation must spend amounts on environmental monitoring,
pollution control equipment, emission fees and other compliance activities. In
addition, compliance with such laws and regulations might result in restrictions
on some of the Corporation's operations. If the Corporation does not comply with
environmental requirements, regulatory agencies could seek to impose civil,
administrative and/or criminal liabilities on the Corporation, as well as seek
to curtail its operations. Under some statutes, private parties could also seek
to impose civil fines or liabilities for property damage, personal

                                       42
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injury and other costs. The Corporation cannot guarantee that lawsuits will not
be commenced or that administrative actions against its generating facilities
will not be commenced in the future. If an action is filed against the
Corporation or its generating facilities, this could require substantial
expenditures to bring the Corporation's generating facilities into compliance
and could have a material adverse effect on the Corporation.

    The Corporation expects to continue to have environmental expenditures in
the future. Stricter standards, greater regulation, increased enforcement by
regulatory authorities, more extensive permitting requirements, an increase in
the number and types of assets operated by the Corporation subject to
environmental regulation and the implementation of the Kyoto Protocols could
increase the amount of these expenditures. Although the scope and extent of new
environmental regulations, permitting requirements and enforcement initiatives,
including their effect on the Corporation's operations, is unclear, they could
materially increase the Corporation's cost of compliance or limit the operation
of some of its facilities.

    Some federal, provincial and state environmental laws impose liability for
the investigation and cleanup of contaminated soil, groundwater, and other
environmental media, and for damages to natural resources, on a wide range of
entities that have some relationship to the contamination. These entities may
include, for example, former owners or operators of a contaminated property and
those who arranged for disposal of the contaminants, as well as the current
owner or operator of such property. In general, liability may be imposed even
though the conduct that caused the environmental condition was lawful at the
time it occurred. Such liability may also be imposed jointly and severally (that
is, with each entity subject to full responsibility for the liability involved,
even though there were others who contributed). In addition, environmental
contamination and other environmental conditions can result in claims for
personal injury, property damages, and/or punitive damages. The Corporation owns
or operates properties, and there are also other properties, at which
contamination exists that could result in liability affecting the Corporation.

RISKS RELATING TO THE CORPORATION'S BUSINESS AND OPERATIONS

UNDER THE ALBERTA PPAS, PURSUANT TO WHICH THE CORPORATION OPERATES MOST OF ITS
FACILITIES IN ALBERTA, THE CORPORATION IS SUBJECT TO CERTAIN RISKS, INCLUDING
THE POSSIBILITIES OF PENALTIES FOR UNPLANNED OUTAGES AND THE BURDEN OF INCREASED
COSTS REQUIRED TO MAINTAIN AND OPERATE ITS GENERATION FACILITIES.

    On January 1, 2001, the Corporation's Alberta coal-fired and hydroelectric
generating plants began operating under the Alberta PPAs which established
committed capacity and electrical energy generation requirements and
availability targets to be achieved by each coal-fired plant, energy and
ancillary services obligations for the hydroelectric plants, and the price at
which power would be supplied. Under the Alberta PPAs applicable to coal-fired
plants, in the event of an unplanned outage, other than an outage determined to
be caused by FORCE MAJEURE, the Corporation must pay a penalty for the lost
production based upon a price equal to the 30-day trailing average of Alberta
market electricity prices. Consequently, an unplanned outage could have a
material adverse effect on the Corporation.

    In addition, because the price at which the Corporation is able to sell its
generation under the Alberta PPAs is fixed, the Corporation bears the full
impact of any increases in its generating costs, which could increase as a
result of a number of factors which are beyond the Corporation's control. A
significant increase in the Corporation's operating costs could have a material
adverse effect on the Corporation. As a result of a shut down of one of its
Wabamun units, the Corporation may be required to make certain penalty payments
mandated by the Wabamun Alberta PPA, which aggregate approximately $90 million.
The Corporation cannot provide any assurance that it will be successful in
defending the claim for penalty payments under the Wabamun Alberta PPA. See
"Business of the Corporation -- Legal Proceedings".

    From time to time during the term of the Alberta PPAs, issues may arise
regarding the intended operation of the Alberta PPAs which may require certain
provisions of the Alberta PPAs to be interpreted, and the interpretations given
may not be favorable to the Corporation. In such circumstances, the Corporation
could be adversely affected.

                                       43
<Page>
CHANGES IN THE MARKET PRICES AND AVAILABILITY OF FUEL SUPPLIES REQUIRED TO
GENERATE ELECTRICITY, AND IN THE PRICE OF ELECTRICITY, MAY ADVERSELY AFFECT THE
CORPORATION.

    The Corporation buys natural gas and some of its coal to supply the fuel
needed to generate the electricity that it sells. The Corporation's financial
results would be adversely affected if the cost of fuel that it must buy to
generate electricity increases to a greater degree than the price that it can
obtain for the electricity that it sells. As the Corporation continues the
development, construction and acquisition of power generation projects, a
greater percentage of its revenues may become subject to this commodity price
risk. Several factors affect the price of fuel, many of which are beyond the
Corporation's control, including:

    - prevailing market prices for fuel, primarily natural gas, including any
      associated transportation costs;

    - demand for energy products;

    - increases in the supply of energy products in the wholesale power
      markets; and

    - the extent of fuel transportation capacity or cost of fuel transportation
      service into the Corporation's markets.

    Changes in any of these factors may increase the Corporation's cost of
producing power or decrease the amount of revenue it receives from the sale of
power, which would adversely affect the Corporation. The price of electricity is
subject to fluctuations and certain of the factors that affect the price of fuel
also affect the price of electricity.

THE CONSTRUCTION AND OPERATION OF THE CORPORATION'S FACILITIES INVOLVES RISKS
THAT MAY ADVERSELY AFFECT THE CORPORATION.

    The construction, expansion, refurbishment, maintenance and operation of
power generation facilities involve risks, including breakdown or failure of
equipment or processes, fuel interruption and performance below expected levels
of output or efficiency. Certain of the Corporation's generation facilities,
particularly in Alberta, were constructed many years ago and may require
significant capital expenditures to maintain peak efficiency or to maintain
operations at all. In addition, weather related interference, work stoppages and
other unforeseen problems may disrupt the development and operations of the
Corporation's facilities and may adversely affect the Corporation.

    The Corporation has entered into on-going maintenance and service agreements
with the manufacturers of critical equipment. If a manufacturer is unable or
unwilling to provide satisfactory maintenance or warranty support, the
Corporation may have to enter into alternative arrangements with other providers
if it cannot perform the maintenance itself. These arrangements could be more
expensive to the Corporation than its current arrangements and this increased
expense could have a material adverse effect on the Corporation.

    While the Corporation maintains spare parts in inventory to replace critical
equipment and maintains insurance for property damage of up to $750 million to
protect against operating risks, these protections may not be adequate to cover
lost revenues or increased expenses and penalties. As a result, the Corporation
may not be able to operate its generation facilities at a level necessary to
comply with sales contracts (including Alberta PPAs), which could result in
significant losses to the Corporation or could limit its ability to produce cash
flows sufficient to enable it to meet its obligations.

    The Corporation may be subject to the risk that it is necessary to operate a
plant at a capacity level beyond that which the Corporation has contracted to
provide steam in order to fulfill a contract. In such circumstances the costs to
produce the steam being sold may exceed the revenues derived therefrom.

THE CORPORATION RELIES ON TRANSMISSION LINES THAT IT DOES NOT OWN OR CONTROL,
WHICH MAY HINDER ITS ABILITY TO DELIVER ELECTRICITY.

    The Corporation depends on transmission and distribution facilities that are
owned and operated by utilities and other power companies to deliver the
electricity the Corporation generates. Any disruption in transmission would
impact the Corporation's ability to sell and deliver electricity. The inability
of the Corporation to effectively sell electricity would have an adverse effect
on the Corporation.

                                       44
<Page>
IN CONNECTION WITH NATURAL GAS-FIRED FACILITIES, THE CORPORATION TYPICALLY
DEPENDS UPON A SINGLE NATURAL GAS DISTRIBUTOR.

    Delivery of natural gas to each of the Corporation's natural gas-fired
facilities is typically handled by a single gas distributor, usually the natural
gas utility for that location. As a result, the Corporation is subject to the
risk that a natural gas distributor suffers disruptions or curtailments in its
ability to deliver the natural gas or that the Corporation is limited in the
amounts of natural gas it is permitted to request. Any disruptions or
curtailments that are not considered to be FORCE MAJEURE could impact the
Corporation's ability to operate natural gas-fired generating facilities, and as
a result, could materially adversely affect the Corporation.

BECAUSE OF THE CORPORATION'S MULTINATIONAL OPERATIONS, THE CORPORATION IS
SUBJECT TO CURRENCY RATE RISK AND REGULATORY AND POLITICAL RISK.

    A significant part of the Corporation's operations, revenues and
expenditures are in U.S., Mexican and Australian currencies. Fluctuations in the
exchange rate between these currencies and the Canadian dollar could have a
negative effect on the Corporation. While the Corporation manages this risk
through its use of hedging instruments, including cross-currency swaps, forward
exchange contracts and foreign currency options, fluctuations in exchange rates
may adversely affect the Corporation. In addition to currency rate risk, the
Corporation's foreign operations may be subject to regulatory and
political risk.

TRADING RISKS MAY HAVE AN ADVERSE IMPACT ON THE CORPORATION.

    The Corporation's trading and marketing business frequently involves the
establishment of trading positions in the wholesale energy markets on both a
long-term and short-term basis. To the extent that the Corporation has long
positions in the energy markets, a downturn in the markets is likely to result
in losses from a decline in the value of such long positions. Conversely, to the
extent that the Corporation enters into forward sales contracts to deliver
energy the Corporation does not own, or take short positions in the energy
markets, an upturn in the energy markets is likely to expose the Corporation to
losses as it attempts to cover any short positions by acquiring energy in a
rising market.

    In addition, from time to time the Corporation may have a trading strategy
consisting of simultaneously holding a long position and a short position, from
which the Corporation expects to earn a profit based on changes in the relative
value of the two positions. If, however, the relative value of the two positions
changes in a direction or manner the Corporation did not anticipate, it could
realize losses from such a paired position.

    If the strategy the Corporation uses to hedge its exposures to these various
risks is not effective, it could incur significant losses. The Corporation's
trading positions are subject to the level of volatility in the energy markets
that, in turn, depends on various factors, including weather in various
geographical areas and short-term supply and demand imbalances, which cannot be
predicted with any certainty. A shift in the energy markets could adversely
affect the Corporation's positions which could also have a material adverse
effect on the Corporation.

IF PURCHASERS OF THE CORPORATION'S ELECTRICITY OR OTHER CONTRACTUAL
COUNTERPARTIES WITH THE CORPORATION DEFAULT ON THEIR OBLIGATIONS, THE
CORPORATION WILL BE MATERIALLY AND ADVERSELY AFFECTED.

    While the Corporation seeks to control its exposure to credit risk by
considering the ability of counterparties to fulfill their obligations under the
related contracts, prior to entering into such contracts the Corporation cannot
guarantee that it will be successful in identifying credit worthy customers.
Moreover, while the Corporation seeks to monitor trading activities to ensure
that the credit limits for counterparties are not exceeded, it cannot guarantee
that it will be successful in doing so. If counterparties to the Corporation's
contracts are unable to meet their obligations, the Corporation could suffer a
reduction in revenue which would adversely effect the Corporation.

                                       45
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THE WHOLESALE POWER INDUSTRY IS RAPIDLY CHANGING AND BECOMING MORE COMPETITIVE,
WHICH MAY ADVERSELY AFFECT THE CORPORATION.

    The trend in the wholesale power industry is toward deregulation, which is
intended to result in increased competition. This increased competition could
reduce price levels across the industry which would negatively impact the
Corporation's ability to sell energy and related products, as well as adversely
affect the Corporation's financial results. In addition, increased competition
may make it more difficult for the Corporation to acquire existing projects and
develop new project opportunities, which would have an adverse effect on
the Corporation.

THE CORPORATION'S PROJECT DEVELOPMENT AND ACQUISITION ACTIVITIES MAY NOT BE
SUCCESSFUL, AND THE CORPORATION MAY NOT BE ABLE TO PURSUE ITS GROWTH STRATEGY.

    The Corporation's strategy calls for the development and acquisition of
energy generation assets, a strategy which involves numerous risks. The
Corporation may not be able to identify attractive development or acquisition
opportunities, or complete development or acquisition projects that it
undertakes and as a result, would not be able to execute its growth strategy.
Factors that may adversely impact the Corporation's growth strategy include the
Corporation's ability to obtain required governmental permits and approvals;
cost overruns or delays in development as a result of labor issues, regulatory
delays or restrictions, or other unanticipated events; and changes in fuel and
electricity prices and the Corporation's ability to manage these changes.

    Any of these factors could give rise to delays, cost overruns or the
termination of the Corporation's development or acquisition projects.
Furthermore, the Corporation may not enter into or retain all of the agreements
necessary for the Corporation to achieve its anticipated contractual control
over generating facilities. If the Corporation is unable to complete the
development of a generating facility or achieve contractual control over an
energy asset, it may incur additional costs, liquidated damages, or termination
of other project contracts, and it may be unable to recover any previous
investment in the project. In addition, construction delays and contractor
performance shortfalls result in the loss of revenues and may, in turn,
adversely affect the Corporation. The failure to complete construction according
to specifications can result in liabilities, reduced efficiency, higher
operating costs and reduced earnings.

THE CORPORATION MAY HAVE DIFFICULTY RAISING NEEDED CAPITAL IN THE FUTURE, WHICH
COULD SIGNIFICANTLY HARM ITS BUSINESS.

    The Corporation will require substantial additional capital to finance its
future growth. Capital expenditures by the Corporation are expected to be at
least $1.0 billion a year for the next few years. Such capital expenditures will
be used to acquire or develop new facilities and expand the Corporation's
existing facilities.

    To the extent that the Corporation's sources of cash and cash flow from
operations are insufficient to fund the Corporation's activities, it may need to
raise additional funds. Additional financing may not be available when needed
and, if such financing is available, it may not be available on terms favorable
to the Corporation.

THE CORPORATION MAY BE ADVERSELY AFFECTED IF ITS SUPPLY OF WATER IS IMPAIRED.

    Hydroelectric and coal-fired plants require continuous water flow for their
operation. Shifts in weather patterns, run-off and other factors beyond the
control of the Corporation may impair the water flow to the Corporation's
facilities. Any water flow impairment would limit the Corporation's ability to
produce and market electricity from these facilities and could have a material
adverse effect on the Corporation.

IF THE CORPORATION IS UNABLE TO SUCCESSFULLY NEGOTIATE NEW COLLECTIVE BARGAINING
AGREEMENTS WITH ITS UNIONIZED WORKFORCE, AS REQUIRED FROM TIME TO TIME, IT WILL
BE ADVERSELY AFFECTED.

    While the Corporation believes it has a good relationship with its unionized
employees, the Corporation cannot guarantee that it will be able to successfully
negotiate or renegotiate its collective bargaining agreements on terms agreeable
to the Corporation. Any problems in negotiating these collective bargaining
agreements could lead to higher employee costs and a work stoppage or strike,
which would have a material adverse effect on the Corporation.

                                       46
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IF THE CORPORATION FAILS TO ATTRACT AND RETAIN KEY PERSONNEL, IT COULD BE
MATERIALLY AND ADVERSELY AFFECTED.

    The loss of any of the Corporation's key personnel or its inability to
attract, train, retain and motivate additional qualified management and other
personnel could have a material adverse effect on the Corporation. Competition
for these personnel is intense and there can be no assurance that the
Corporation will be successful in this regard.

INSURANCE COVERAGE MAY NOT BE SUFFICIENT.

    The Corporation has insurance for its generation facilities, including
all-risk property damage insurance, commercial general public liability
insurance, boiler and machinery coverage, replacement power and business
interruption insurance in amounts and with deductibles that the Corporation
considers appropriate. The Corporation's insurance coverage may not be available
in the future on commercially reasonable terms nor that the insurance proceeds
that it receives for any loss of or any damage to any of its generation
facilities may be sufficient to permit it to continue to make payments on its
debt, including any debt securities they may be offered under this Prospectus.
In addition, due to the events of September 11, 2001, the Corporation is no
longer insured against losses resulting from terrorist attacks. The Corporation
may suffer significant losses if any of its generation assets were affected by a
terrorist attack because this risk is no longer insured.

THE CORPORATION'S DEBT SECURITIES WILL BE STRUCTURALLY SUBORDINATED TO ANY DEBT
OF ITS SUBSIDIARIES THAT IS CURRENTLY OUTSTANDING OR MAY BE INCURRED IN THE
FUTURE.

    The Corporation operates its business through and a majority of its assets
are held by its subsidiaries, including partnerships. The Corporation's results
of operations and ability to service indebtedness, including the debt
securities, are dependent upon the results of operations of its subsidiaries and
the payment of funds by these subsidiaries to it in the form of loans, dividends
or otherwise. The Corporation's subsidiaries will not have an obligation to pay
amounts due pursuant to any debt securities or make any funds available for
payment of debt securities, whether by dividends, interests, loans, advances or
other payments. In addition, the payment of dividends and the making of loans,
advances and other payments to the Corporation by its subsidiaries may be
subject to statutory or contractual restrictions.

    In the event of the liquidation of any subsidiary, the assets of the
subsidiary would be used first to repay the indebtedness of the subsidiary,
including trade payables or obligations under any guarantees, prior to being
used to pay the Corporation's indebtedness, including any debt securities. As at
March 31, 2002, the Corporation's subsidiaries had outstanding $1,173.7 million
aggregate principal amount of long-term debt. Such indebtedness and any other
future indebtedness of such subsidiaries would be structurally senior to the
debt securities issued by the Corporation. The Indenture pursuant to which the
debt securities will be issued does not limit the Corporation's ability or the
ability of its subsidiaries to incur additional unsecured indebtedness.
Commencing in 1999, the Corporation implemented a financing strategy whereby all
external capital was raised by the Corporation directly and reinvested in
various subsidiaries as required. From 1999 to March 31, 2002, approximately
$600 million aggregate principal amount of long-term debt and preferred shares
of the subsidiaries was refinanced through external debt issued at the
TransAlta level.

    The Corporation's subsidiaries have financed some investments using
non-recourse project financing. Each non-recourse project loan is structured to
be repaid out of cash flow provided by the investment. In the event of a default
under a financing agreement which is not cured, the lenders would generally have
rights to the related assets. In the event of foreclosure after a default, the
Corporation's subsidiary may lose its equity in the asset or may not be entitled
to any cash that the asset may generate. Although a default under a project loan
will not cause a default with respect to the debt securities, it may materially
affect the Corporation's ability to service its outstanding indebtedness,
including the debt securities.

                                       47
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                                 LEGAL MATTERS

    Unless otherwise specified in the Prospectus Supplement relating to the
Securities, certain legal matters relating to Canadian law will be passed upon
for the Corporation by McCarthy Tetrault LLP, Calgary, Alberta, Canada, and
certain legal matters relating to United States law will be passed upon for the
Corporation by Latham & Watkins, New York, New York. In addition, certain legal
matters relating to United States law will be passed upon for any underwriters,
dealers or agents by Shearman & Sterling, Toronto, Ontario, Canada.

    The partners and associates of McCarthy Tetrault LLP, Latham & Watkins and
Shearman & Sterling as a group beneficially own, directly or indirectly, less
than 1% of the outstanding securities of any class or series of
the Corporation.

                                    EXPERTS

    The consolidated annual financial statements for the years ended
December 31, 2001 and 2000 incorporated by reference in this Prospectus have
been audited by Ernst & Young LLP, Chartered Accountants, as set forth in their
report included therein and incorporated herein by reference. The financial
statements referred to above are incorporated herein by reference in reliance
upon the report of such firm and upon the authority of such firm as experts in
auditing and accounting.


                                    AUDITORS



    The partners of Ernst & Young LLP as a group beneficially own, directly or
indirectly, no securities of any class or series of the Corporation.


             DOCUMENTS FILED AS PART OF THE REGISTRATION STATEMENT

    The following documents have been filed with the SEC as part of the
Registration Statement of which this Prospectus forms a part: the documents
listed herein under "Where You Can Find More Information; Documents Incorporated
by Reference"; consent of Ernst & Young LLP, Chartered Accountants; certain
powers of attorney; the form of Indenture; and the Statement of Eligibility of
the Trustee on Form T-1.

                        ENFORCEMENT OF CIVIL LIABILITIES

    The Corporation is a Canadian corporation, and the majority of its assets
and operations are located, and the majority of its revenues are derived,
outside the United States. The Corporation has appointed CT Corporation System,
New York, New York, as its agent to receive service of process with respect to
any action brought against it in any federal or state court in the State of
New York arising from this offering. However, it may not be possible for
investors to enforce outside the United States judgments against the Corporation
obtained in the United States in any such actions, including actions predicated
upon the civil liability provisions of the United States federal and state
securities laws. In addition, certain of the directors and officers of the
Corporation are residents of Canada or other jurisdictions outside of the United
States, and all or a substantial portion of the assets of those directors and
officers are or may be located outside the United States. As a result, it may
not be possible for investors to effect service of process within the United
States upon those persons, or to enforce against them judgments obtained in
United States courts, including judgments predicated upon the civil liability
provisions of United Stated federal and state securities laws.

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- --------------------------------------------------------------------------------
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                                US$1,000,000,000

                             TRANSALTA CORPORATION

                                 COMMON SHARES
                             FIRST PREFERRED SHARES
                                DEBT SECURITIES
                                    WARRANTS

                                 --------------
                                   PROSPECTUS

                                 --------------


                                  MAY 14, 2002


- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<Page>
                                    PART II

                          INFORMATION NOT REQUIRED TO
                            BE DELIVERED TO OFFEREES
                                 OR PURCHASERS

INDEMNIFICATION

    The Registrant may indemnify a director or officer of the Registrant, a
former director or officer of the Registrant or another individual who acts or
acted at the Registrant's request as a director or officer, or an individual
acting in a similar capacity, of another entity, against all costs, charges, and
expenses, including an amount paid to settle an action or satisfy a judgment,
reasonably incurred by the individual in respect of any civil, criminal,
administrative, investigative or other proceeding in which the individual is
involved because of that association with the Registrant or other entity.
However, the Registrant may advance moneys to a director, officer or other
individual for the costs, charges and expenses of a proceeding referred to
above. The individual shall repay the moneys if the individual does not fulfill
the conditions in (a) and (b) below. The Registrant may not indemnify an
individual unless the individual (a) acted honestly and in good faith with a
view to the best interests of the Registrant, or, as the case may be, to the
best interests of the other entity for which the individual acted as director or
officer or in in a similar capacity at the Registrant's request; and (b) in the
case of a criminal or administrative action or proceeding that is enforced by
monetary penalty, the individual had reasonable grounds for believing that the
individual's conduct was lawful. The Registrant may with the approval of a
court, indemnify an individual referred to above, or advance money's for the
cost, charges and expenses of a proceeding, in respect of an action by or on
behalf of the Registrant or other entity to procure a judgment in its favor, to
which the individual is made a party because of the individual's association
with the Registrant or other entity as described above against all costs,
charges and expenses reasonably incurred by the individual in connection with
such action, if the individual fulfills the conditions set out in (a) and
(b) above. Notwithstanding the foregoing, an individual is entitled to indemnity
from the Registrant in respect of costs, charges and expenses, reasonably
incurred by the individual in the defence of any civil, criminal, administrative
or other proceeding to which the individual is subject because of the
individuals association with the Registrant or other entity referred to above,
if the individual seeking indemnity was not judged by a court or other competent
authority to have committed any fault or omitted to do anything that the
individual ought to have done, and if the individual fulfills the conditions set
out in (a) and (b) above.

    A by-law of the Registrant provides that the Registrant shall indemnify a
director or officer of the Registrant, a former director or officer of the
Registrant or a person who acts or acted at the Registrant's request as a
director or officer of a corporate body of which the Registrant is or was a
shareholder or creditor, and the heirs and legal representatives thereof, to the
extent permitted by the Canada Business Corporation Act ("CBCA") or otherwise
by law.

    The Registrant maintains a directors' and officers' liability policy which
provides coverage to the Registrant for all directors' and officers' related
claims, losses and cost in any year, subject to policy limits and deductibles.

    The Registrant has entered into indemnification agreements with each of its
officers and directors pursuant to which they are indemnified to the fullest
extent permitted by the CBCA. Pursuant to the terms of these agreements the
Registrant maintains errors and omissions insurance for its officers and
directors while they remain an officer or director and for a period of 10 years
thereafter.

    The Registrant expects that any underwriting agreement pursuant to which it
sells securities covered by this Registration Statement will contain provisions
under which the Registrant will indemnity the underwriters, their directors,
officers, controlling persons and other persons from various liabilities
including liabilities under the Securities Act of 1933, as amended.

    Insofar as indemnification for liabilities arising under the Securities Act
of 1933, as amended, may be permitted pursuant to the foregoing provisions to
directors, officers, persons controlling the registrant or other persons, the
Registrant has been informed that in the opinion of the U.S. Securities and
Exchange Commission such indemnification is against public policy as expressed
in such Act and is therefore unenforceable.

                                      II-1
<Page>
                                    EXHIBITS


<Table>
                      
Exhibit 4.1              Annual Information Form of TransAlta Corporation, dated
                         May 1, 2002, for the year ended December 31, 2001
                         (incorporated by reference to TransAlta Corporation's
                         Form 40-F filed on May 6, 2002).

Exhibit 4.2              Audited Consolidated Financial Statements of TransAlta
                         Corporation, for the years ended December 31, 2001, and 2000
                         together with the related notes thereto and the auditors'
                         reports thereon (incorporated by reference to TransAlta
                         Corporation's Form 40-F filed on May 6, 2002).

Exhibit 4.3              Management's Discussion and Analysis for the fiscal year
                         ended December 31, 2001 (incorporated by reference to
                         TransAlta Corporation's Form 6-K filed on March 4, 2002).

Exhibit 4.4              Management proxy circular dated March 14, 2002 (incorporated
                         by reference to TransAlta Corporation's Form 40-F filed on
                         May 6, 2002).

Exhibit 4.5              TransAlta Corporation Dividend Reinvestment and Share
                         Purchase Plan.

Exhibit 4.6              Management's Discussion and Analysis for the three month
                         period ended March 31, 2002 (incorporated by reference to
                         TransAlta Corporation's Form 6-K filed on April 18, 2002).

Exhibit 4.7              Unaudited Consolidated Interim Financial Statements of
                         TransAlta Corporation, for the three month period ended
                         March 31, 2002 (incorporated by reference to TransAlta
                         Corporation's Form 6-K filed on April 18, 2002).

Exhibit 4.8              The first two paragraphs of the Corporation's press release
                         dated May 2, 2002 relating to the entering into of a
                         memorandum of understanding with EPCOR Utilities Inc.
                         (incorporated by reference to TransAlta Corporation's
                         Form 6-K filed on May 3, 2002).

Exhibit 4.9              The reconciliation to U.S. GAAP of the unaudited
                         consolidated interim financial statements of the Corporation
                         for the three month periods ended March 31, 2002 and 2001
                         (incorporated by reference to TransAlta Corporation's
                         Form 6-K filed on May 7, 2002).

Exhibit 5.1              Consent of Ernst & Young LLP (incorporated by reference to
                         TransAlta Corporation's Form F-10 filed on May 7, 2000).

Exhibit 6.1              Power of Attorney (incorporated by reference to TransAlta
                         Corporation's Form F-10 filed on May 7, 2000, included on
                         Page III-3 of such Registration Statement).

Exhibit 7.1              Form of Base Indenture between TransAlta Corporation and
                         Bank of New York, as trustee.

Exhibit 7.2              Statement of Eligibility of the Trustee on Form T-1.
</Table>


                                      II-2
<Page>
                                    PART III

                          UNDERTAKINGS AND CONSENT TO
                               SERVICE OF PROCESS

ITEM 1.  UNDERTAKINGS.

    The registrant undertakes to make available, in person or by telephone,
representatives to respond to inquiries made by the Commission staff, and to
furnish promptly, when requested to do so by the Commission staff, information
relating to the securities registered pursuant to Form F-10 or to transactions
in said securities.

ITEM 2.  CONSENT TO SERVICE OF PROCESS.

    Concurrently with the filing of this Registration Statement on Form F-10,
the Registrant is filing with the Commission a written irrevocable consent and
power of attorney on Form F-X.

                                     III-1
<Page>
                                   SIGNATURES


    Pursuant to the requirements of the Securities Act of 1933, as amended, the
registrant certifies that it has reasonable grounds to believe that it meets all
of the requirements for filing on Form F-10 and has duly caused this Amendment
to the Registration Statement to be signed on its behalf by the undersigned,
thereunto duly authorized, in the City of Calgary, Province of Alberta, Canada,
on May 10, 2002.



<Table>
                                              
                                               TRANSALTA CORPORATION
                                               (Registrant)

                                               By:  /s/ STEPHEN G. SNYDER
                                                    -----------------------------------------------------
                                                    Name: Stephen G. Snyder
                                                    Title:President, Chief Executive Officer
                                                          and Director (Principal Executive Officer)
</Table>


                                     III-2
<Page>

                           AUTHORIZED REPRESENTATIVE



    Pursuant to the requirements of Section 6(a) of the Securities Act, the
undersigned has signed this Registration Statement solely in their capacity as
the duly Authorized Representative of the Registrant in the United States on
May 9, 2002.



<Table>
                                              
                                               TRANSALTA USA INC.

                                               By:  /s/ CHARLES W. BATES
                                                    -----------------------------------------------------
                                                    Name: Charles W. Bates
                                                    Title: Assistant Vice President
</Table>


                                     III-3
<Page>
                               INDEX TO EXHIBITS


<Table>
                      
Exhibit 4.1              Annual Information Form of TransAlta Corporation, dated
                         May 1, 2002, for the year ended December 31, 2001
                         (incorporated by reference to TransAlta Corporation's
                         Form 40-F filed on May 6, 2002).

Exhibit 4.2              Audited Consolidated Financial Statements of TransAlta
                         Corporation, for the years ended December 31, 2001, and 2000
                         together with the related notes thereto and the auditors'
                         reports thereon (incorporated by reference to TransAlta
                         Corporation's Form 40-F filed on May 6, 2002).

Exhibit 4.3              Management's Discussion and Analysis for the fiscal year
                         ended December 31, 2001 (incorporated by reference to
                         TransAlta Corporation's Form 6-K filed on March 4, 2002).

Exhibit 4.4              Management proxy circular dated March 14, 2002 (incorporated
                         by reference to TransAlta Corporation's Form 40-F filed on
                         May 6, 2002).

Exhibit 4.5              TransAlta Corporation Dividend Reinvestment and Share
                         Purchase Plan.

Exhibit 4.6              Management's Discussion and Analysis for the three month
                         period ended March 31, 2002 (incorporated by reference to
                         TransAlta Corporation's Form 6-K filed on April 18, 2002).

Exhibit 4.7              Unaudited Consolidated Interim Financial Statements of
                         TransAlta Corporation, for the three month period ended
                         March 31, 2002 (incorporated by reference to TransAlta
                         Corporation's Form 6-K filed on April 18, 2002).

Exhibit 4.8              The first two paragraphs of the Corporation's press release
                         dated May 2, 2002 relating to the entering into of a
                         memorandum of understanding with EPCOR Utilities Inc.
                         (incorporated by reference to TransAlta Corporation's
                         Form 6-K filed on May 3, 2002).

Exhibit 4.9              The reconciliation to U.S. GAAP of the unaudited
                         consolidated interim financial statements of the Corporation
                         for the three month periods ended March 31, 2002 and 2001
                         (incorporated by reference to TransAlta Corporation's
                         Form 6-K filed on May 7, 2002).

Exhibit 5.1              Consent of Ernst & Young LLP (incorporated by reference to
                         TransAlta Corporation's Form F-10 filed on May 7, 2000).

Exhibit 6.1              Power of Attorney (incorporated by reference to TransAlta
                         Corporation's Form F-10 filed on May 7, 2000, included on
                         Page III-3 of such Registration Statement).

Exhibit 7.1              Form of Base Indenture between TransAlta Corporation and
                         Bank of New York, as trustee.

Exhibit 7.2              Statement of Eligibility of the Trustee on Form T-1.
</Table>


                                     III-4