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                                                                     EXHIBIT 3.1



               AMENDED AND RESTATED CERTIFICATE OF INCORPORATION
                       O'BRIEN ENVIRONMENTAL ENERGY, INC.


O'Brien Environmental Energy, Inc., a corporation organized and existing under
the laws of the State of Delaware, hereby certifies as follows: The original
name of the Corporation was O'Brien Energy Systems, Inc.  The date of filing of
its original Certificate of Incorporation with the Secretary of State was
December 5, 1983.

      1. This Amended and Restated Certificate of Incorporation restates and
further amends the Certificate of Incorporation of the Corporation to read as
set forth herein.

      2. The text of the Certificate of Incorporation as heretofore amended or
supplemented is hereby further amended and restated to read in full as follows:

FIRST:The name of the Corporation is:

NRG GENERATING (U.S.) INC.

SECOND:The address of the registered office of the Corporation in the State of
Delaware is Corporation Trust Center, 1209 Orange Street in the City of
Wilmington, County of New Castle, and the name of its registered agent at that
address is The Corporation Trust Company.

THIRD:The purpose of the Corporation is to engage in any lawful act or activity
for which corporations may be organized under the General Corporation Law of
Delaware.

FOURTH:(a)  The total number of shares of stock which the Corporation is
authorized to issue is seventy thousand consisting of fifty million
(50,000,000) shares of common stock, having a par value of one cent ($.01) per
share and twenty million (20,000,000) shares of Preferred Stock, having a par
value of one cent ($.01) per share.

(b)The Corporation shall not issue any nonvoting equity securities provided
that this provision, which is included in this Certificate of Incorporation in
compliance with Section 1123(a)(6) of the United States Bankruptcy Code of
1978, as amended, shall have no force or effect beyond that required by such
Section 1123(a)(6) and shall be effective only for so long as such Section
1123(a)(6) is in effect and applicable to the Corporation.

(c)Shares of Preferred Stock may be issued from time to time in one or more
series.  The Board of Directors is hereby authorized





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to fix the voting rights, designations, powers, preferences and the relative,
participating, optional or other rights, if any, and the qualifications,
limitations or restrictions thereof, of any wholly unissued series of Preferred
Stock; and to fix the number of shares constituting such series (but not below
the number of shares thereof then outstanding).

                 FIFTH:   (a)  Except as provided below, the bylaws of the
Corporation may only be made, repealed, altered, amended or rescinded by (i)
the stockholders of the Corporation by the vote of the holders of not less than
sixty percent (60%) of the total voting power of all outstanding shares of
voting stock of the Corporation or (ii) the directors of the Corporation by the
vote of a majority of the entire board of directors present at a meeting at
which a quorum is present.

                 (b)      Section 1.7(b) (regarding action by written consent
of stockholders); Section 1.11 (regarding notice of stockholder nominations and
other stockholder business); Section 2.1(b) (regarding the number of
directors); Section 2.10 (regarding Independent Directors); and Section 3.2
(regarding the Independent Directors Committee), of the bylaws of the
Corporation may only be repealed, altered, amended or rescinded by (i) the
stockholders of the Corporation by a vote of the holders of not less than
seventy-five percent (75%) of the total voting power of all outstanding shares
of voting stock of the Corporation or (ii) the directors of the Corporation by
the affirmative vote of no fewer than the lesser of all of the directors then
in office or six (6) of the Corporation's directors; provided however, that
Section 2.10 (regarding Independent Directors) and Section 3.2 (regarding
the Independent Directors Committee) may be altered or amended pursuant to the
provisions of subparagraph (a) of Article Fifth to the extent necessary to
comply with the provisions of the applicable listing requirements of any
exchange or market system over which the securities of the Corporation are to
be traded.

                 SIXTH:   A director of the Corporation shall not be personally
liable to the Corporation or its stockholders for monetary damages for breach
of fiduciary duty as a director, except for liability (i) for any breach of the
director's duty of loyalty to the Corporation or its stockholders, (ii) for
acts or omissions not in good faith or which involve intentional misconduct or
a knowing violation of law, (iii) under Section 174 of the Delaware General
Corporation Law, or (iv) for any transaction from which the director derived an
improper personal benefit.  If the Delaware General Corporation Law is amended
to authorize corporate action further eliminating or limiting the personal
liability of directors, then the liability of a director of the Corporation
shall be eliminated or limited to the fullest extent permitted by the Delaware
General Corporation Law, as so amended.  Any repeal or modification of this
provision shall not adversely affect any right or protection of a director of
the Corporation existing at the time of such repeal or modification.





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                 SEVENTH:         (a)  Until April 30, 2002, (i) any attempted
sale, transfer, assignment, conveyance, grant, pledge, gift or other
disposition of any share or shares of stock of the Corporation (within the
meaning of Section 382 of the Internal Revenue Code of 1986 (the "Code")), or
any option or right to purchase such stock, as defined in the Treasury
Regulations under Section 382 of the Code, to any person or entity (or group of
persons or entities acting in concert) who either directly or indirectly owns
or would be treated as owning, or whose shares are or would be attributed to
any person or entity who directly or indirectly owns or would be treated as
owning, in either case prior to the purported transfer and after giving effect
to the applicable attribution rules of the Code and applicable Treasury
Regulations, 5 percent or more of the value of the outstanding stock of the
Corporation or otherwise treated as a 5 percent stockholder (within the meaning
of Section 382 of the Code), regardless of the percent or the value of the
stock owned, shall be void ab initio insofar as it purports to transfer
ownership or rights in respect of such stock to the purported transferee and
(ii) any attempted sale, transfer, assignment, conveyance, grant, gift, pledge
or other disposition of any share of stock of the Corporation (within the
meaning of Section 382 of the Code) or any option or right to purchase such
stock, as defined in the Treasury Regulations under Section 382 of the Code, to
any person or entity (or group of persons or entities acting in concert) not
described in clause (i) who directly or indirectly would own, or whose shares
would be attributed to any person or entity who directly or indirectly would
own in each case as a result of the purported transfer and after giving effect
to the applicable attribution rules of the Code and applicable Treasury
Regulations, 5 percent or more of the value of any of the stock of the
Corporation (or otherwise treated as a 5-percent stockholder within the meaning
of Section 382 of the Code), shall, as to that number of shares causing such
person or entity to be a 5-percent stockholder, be void ab initio insofar as it
purports to transfer ownership or rights in respect of such stock to the
purported transferee; provided, however, that neither of the foregoing clauses
(i) and (ii) shall prevent a valid transfer if (A) the transferor obtains the
written approval of the board of directors of the Corporation which approval
shall not be unreasonably withheld and provides the Corporation with an opinion
of counsel reasonably satisfactory to the Corporation that (assuming, as of the
date of such opinion, the full exercise of (i) all warrants issued under, and
(ii) any options granted pursuant to any stock option plan of the Corporation)
the transfer shall not result in an ownership change within the meaning of
Section 382 of the Code and any successor thereto or (B) a tender offer, within
the meaning of the Securities Exchange Act of 1934, as amended, and pursuant to
the rules and regulations thereof, is made by a bona fide third-party purchaser
to purchase at least sixty- six and two-thirds percent (66-2/3%) of the issued
and outstanding common stock of the Corporation and the offeror (i) agrees to
effect, within ninety (90) days of the consummation of the tender offer, a back
end merger in which all non- tendering stockholders would receive the same
consideration





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as paid in the tender offer, and (ii) has received the tender of sufficient
shares to effect such merger.  Without limiting or restricting in any manner
the effectiveness of the foregoing provisions, the Corporation and any
transferor may rely and shall be protected in relying on the Corporation's
stockholder lists and stock transfer records for all purposes relating to any
opinion required hereunder.

                 (b)      In the absence of specific board approval, a
purported transfer of shares in excess of the shares that can be transferred
pursuant to this Article SEVENTH (the "Prohibited Shares") to the purported
acquiror (the "Purported Acquiror") is not effective to transfer ownership of
such Prohibited Shares.  On demand by the Corporation, which demand must be
made within thirty (30) days of the time the Corporation learns of the transfer
of the Prohibited Shares, a Purported Acquiror must transfer any certificate or
other evidence of ownership of the Prohibited Shares within the Purported
Acquiror's possession or control, together with any dividends or other
distributions ("Distributions") that were received by the Purported Acquiror
from the Corporation with respect to the Prohibited Shares, to an agent
designated by the Corporation (the "Agent").  The Agent will sell the
Prohibited Shares in an arm's length transaction (over a stock exchange, if
possible), and the Purported Acquiror will receive an amount of sales proceeds
not in excess of the price paid or consideration surrendered by the Purported
Acquiror for the Prohibited Shares (or the fair market value of the Prohibited
Shares at the time of an attempted transfer to the Purported Acquiror by gift,
inheritance, or a similar transfer).  If the Purported Acquiror has resold the
Prohibited Shares prior to receiving the Corporation's demand to surrender the
Prohibited Shares to the Agent, the Purported Acquiror shall be deemed to have
sold the Prohibited Shares as an agent for the initial transferor, and shall be
required to transfer to the Agent any proceeds of such sale and any
Distributions.

                 (c)      If the initial transferor can be identified, the
Agent will pay to it any sales proceeds in excess of those due to the Purported
Acquiror, together with any Distributions received by the Agent.  If the
initial transferor cannot be identified within ninety (90) days, the Agent may
pay any such amounts to a charity of its choosing.  In no event shall amounts
paid to the Agent inure to the benefit of the Corporation or the Agent, but
such amounts may be used to cover expenses of the Agent in attempting to
identify the initial transferor.  If the Purported Acquiror fails to surrender
the Prohibited Shares within the next thirty (30) business days from the demand
by the Corporation, then the Corporation will institute legal proceedings to
compel the surrender.  The Corporation shall be entitled to damages, including
reasonable attorneys' fees and costs, from the Purported Acquiror, on account
of such purported transfer.

                 EIGHTH:  The affirmative vote of the holders of greater than
sixty-six and two thirds percent (66-2/3%) of the total voting power of all
outstanding shares of voting stock of





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the Corporation shall be required for the approval of any proposal (1) that the
Corporation merge or consolidate with any corporation, person, partnership,
trust or other entity ("Entity"), or (2) that the Corporation sell or exchange
all or substantially all of its assets or business, or (3) that the Corporation
issue or deliver any stock or other securities of its issue in exchange or
payment for any properties or assets of any Entity or securities issued by any
Entity, and to effect such transaction the approval of stockholders of the
Corporation is required by law or by any agreement between the Corporation and
any national securities exchange.

                 NINTH:   (a)  Any attempted sale, transfer, assignment,
conveyance, pledge or other disposition of any share of the Corporation's
common stock to any Electric Utility Interest (as defined below) shall be null
and void ab initio.  No employee or agent, including any independent transfer
agent or registrar of this Corporation, shall be permitted to record any
attempted or purported transfer made in violation of this provision, and no
intended transferee of shares of this Corporation's common stock attempted to
be transferred in violation of this Article NINTH shall be recognized as a
holder of such shares for any purpose whatsoever, including, but not limited
to, the right to vote such shares of common stock or to receive dividends or
other distributions in respect thereof, if any.  The transferor and any such
intended transferee shall be deemed to have appointed the Corporation as
attorney-in-fact, with full power of substitution and full power and authority,
in the name and on behalf of the intended transferor and transferee, to sell,
assign and transfer the shares of Common Stock of the Corporation attempted to
be transferred in violation of this Article NINTH, and to do all lawful acts
and execute all documents deemed necessary or advisable to effect such sale,
assignment and transfer, in an arm's-length transaction, to another entity or
person; provided that the sale, assignment and transfer to such other entity or
person does not violate the provisions of this Article NINTH.  The Corporation
shall apply the proceeds of any such sale first, to pay the expenses of the
sale; second, to pay the intended transferee on whose behalf the shares were
sold, an amount equal to (i) the sum of the intended transferee's cost of such
shares (inclusive of brokerage fees and expenses), plus interest on such cost
at the then minimum rate of interest which would prevent interest on a
non-interest bearing obligation from being imputed by the Internal Revenue
Service, less the amount of any dividends or other distributions inadvertently
paid to said intended transferee in respect of such shares, or (ii) the balance
of such proceeds, whichever is less; and third, the balance of such proceeds,
if any, shall be paid to the Corporation.  Notwithstanding the foregoing, the
Corporation shall not provide any proceeds to the intended transferee, if such
intended transferee has received consideration from any subsequent attempted
transfer.

                 (b)      This Corporation shall take all appropriate legal
action to enforce the provisions of this Article NINTH in every





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case where there has been an attempted or purported transfer made in violation
thereof.  In taking any action hereunder, this Corporation, and its directors,
officers and agents, will be fully protected in relying upon any notice, paper
or other document reasonably believed by this Corporation or any such person to
be genuine and sufficient, and, to the extent permitted by law, in no event
shall this Corporation, or any of its directors, officers or agents, be liable
for any act performed or omitted to be performed hereunder in the absence of
gross negligence or willful misconduct.  This Corporation and each of its
directors, officers and agents may consult with counsel in connection with its
respective duties hereunder and, to the extent permitted by law, each shall be
fully protected by any act taken, suffered or permitted in good faith in
accordance with the advice of such counsel.

                 (c)      For purposes of this Article NINTH, the term
"Electric Utility Interest" refers to an electric utility or utilities or an
electric utility holding company or companies, or any affiliate of either, in
each case as those terms are utilized by the Federal Energy Regulatory
Commission ("FERC") in regulations or orders implementing the Public Utility
Regulatory Policies Act of 1978, as amended, and its successors ("PURPA") , if
such entity's interest in this Corporation would be a utility interest for the
purposes of 10 C.F.R. S 292.206.

                 (d)      Whenever it is deemed by the board of directors to be
prudent in protecting, preserving or obtaining for any of its projects
(including projects in which this Corporation or a subsidiary has an interest,
whether by ownership, lease or contract) the status of a "Qualifying Facility"
(as defined under PURPA), the board of directors of this Corporation may
require to be filed with this Corporation as a condition to permitting any
proposed transfer, and/or the registration of any transfer, of any shares of
this Corporation's common stock a statement of affidavit from any proposed
transferee to the effect that such transferee is not an "Electric Utility
Interest," as defined herein.

                 (e)      The Corporation may, at any time that the Board of
Directors of the Corporation deems necessary or advisable to protect, preserve
or obtain for any of its projects the status of a "Qualifying Facility", redeem
any shares of its capital stock beneficially owned by any Electric Utility
Interest at a redemption price equal to the "Fair Market Value" (as defined in
subsection (h) below) of such shares of capital stock.

                 (f)      In the event the Corporation shall redeem any shares
of its capital stock pursuant to subsection (e) above, notice of such
redemption shall be given by first class mail, postage prepaid, mailed not less
than thirty (30) days nor more than sixty (60) days prior to the redemption
date, to each holder of record of the shares to be redeemed at such holder's
address as the same appears on the books of the Corporation; provided, however,
that no failure to mail such notice nor any defect





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therein shall affect the validity of the proceeding for the redemption of any
shares of capital stock to be redeemed except as to the holder to whom the
Corporation has failed to mail said notice or except as to the holder whose
notice was defective.  Each such notice shall state: (i) the redemption date;
(ii) the number of shares of capital stock to be redeemed and, if less than all
the shares held by such holder are to be redeemed from such holder, the number
of shares to be redeemed from such holder; and (iii) the place or places where
certificates for such shares are to be surrendered for payment of the
redemption price.

                 (g)      Notice having been mailed as aforesaid, from and
after the redemption date (unless the Corporation shall fail to provide money
for the payment of the redemption price of the shares called for redemption)
the shares of capital stock so called for redemption shall no longer be deemed
to be outstanding, and all rights of the holders thereof as stockholders of the
Corporation (except the right to receive from the Corporation the redemption
price) shall cease.  Upon surrender in accordance with said notice of the
certificates for any shares so redeemed (properly endorsed or assigned for
transfer, if the board of directors shall so require and the notice shall so
state), such shares shall be redeemed by the Corporation at the redemption
price. In case fewer than all of the shares represented by any such certificate
are redeemed, a new certificate shall be issued representing the unredeemed
shares without cost to the holder thereof.

                 (h)      For purposes of this Article NINTH, "Fair Market
Value" shall mean the average of the closing sale prices during the 30-day
period immediately preceding the redemption date of a share of capital stock of
the Corporation as reported on the American Stock Exchange, Inc. (the "Amex"),
or, if such stock is not then listed on the Amex, on the principal United
States securities exchange registered under the Securities Exchange Act of
1934, as amended, on which such stock is listed, or, if such stock is not then
listed on any such exchange, the average of the closing sale prices or closing
bid quotations (whichever is higher, if both are reported) with respect to a
share of such stock during the 30-day period immediately preceding the
redemption date of a share of such stock on the National Association of
Securities Dealers, Inc. National Market System or any system then in use, or
if no such quotations are available, the fair market value on the redemption
date of a share of such stock as determined by the board of directors in good
faith.

                 (i)      The board of directors of this Corporation shall have
the right to determine whether any transferee or purported transferee of shares
of common stock of this Corporation is an "Electric Utility Interest" and to
determine whether this Corporation's projects (including projects in which this
Corporation or a subsidiary has an interest, whether by ownership, lease or
contract) meet the requirements for "Qualifying Facility" status under PURPA.





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                 (j)      Nothing contained in this Article NINTH shall limit
the authority of the board of directors of this Corporation to take such other
action as it deems necessary or advisable to protect this Corporation and
interests of its stockholders by protecting, preserving or obtaining for any of
this Corporation's projects (including projects in which this Corporation or a
subsidiary has an interest, whether by ownership, lease or contract) the status
of a "Qualifying Facility" under PURPA.

                 (k)      All certificates representing shares of this
Corporation's common stock shall bear the following legend:

                          The sale, transfer, assignment, conveyance, pledge or
                          other disposition of any of the shares represented by
                          this certificate to any "Electric Utility Interest"
                          (as hereinafter defined) is restricted in accordance
                          with the provisions of the Certificate of
                          Incorporation of the Corporation.  For these
                          purposes, the term "Electric Utility Interest" refers
                          to an electric utility or utilities or an electric
                          utility holding company or companies, or any
                          affiliate of either, in each case as those terms are
                          utilized by the Federal Energy Regulatory Commission
                          ("FERC") in regulations or orders implementing the
                          Public Utility Regulatory Policies Act of 1978, as
                          amended, and its successors ("PURPA"), if such
                          entity's interest in the corporation would be utility
                          interest for purposes of 10 C.F.R. S 292.206.

                 TENTH:   The provisions set forth in this Article TENTH and
subparagraph (a) of Article FIFTH (regarding the alteration of bylaws) may not
be repealed or amended in any respect unless such repeal or amendment is
approved by the affirmative vote of the holders of not less than sixty percent
(60%) of the total voting power of all outstanding shares of voting stock of
the Corporation.

                 ELEVENTH:  The provisions set forth in this Article Eleventh,
in subparagraph (b) of Article FIFTH (regarding the alteration of certain
bylaws) and in Article EIGHTH (regarding the greater than sixty-six and two
thirds percent (66-2/3%) vote of stockholders required for certain mergers or
other corporate combinations), may not be repealed or amended in any respect
unless such repeal or amendment is approved by the affirmative vote of holders
of not less than seventy-five percent (75%) of the total voting power of all
outstanding shares of voting stock of the Corporation.

                 TWELFTH:         The Corporation reserves the right to amend,
alter, change or repeal any provision contained in this Certificate of
Incorporation, in the manner now or hereafter prescribed by statute and in
accordance with Articles TENTH and ELEVENTH hereof.





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        IN WITNESS WHEREOF, this Amended and Restated Certificate of
Incorporation which restates in its entirety the provisions of the
Corporation's Certificate of Incorporation, having been duly adopted by the
Board of Directors and the stockholders of the Corporation in accordance with
the provisions of Section 242 & 245 of the General Corporation Law of the State
of Delaware, has been executed on the 30th day of April, 1996.

                                      /s/ Leonard A. Bluhm         
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                                    Leonard A. Bluhm
                                    Designated Responsible Person

ATTEST

  /s/ Craig A. Mataczynski          
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Craig A. Mataczynski
Designated Responsible Person





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