UNITED STATES
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549

                                    FORM 8-K
                                 CURRENT REPORT
                     Pursuant to Section 13 or 15(d) of the
                         Securities Exchange Act of 1934

      Date of report (Date of earliest event reported): September 27, 2005

                            BEACON POWER CORPORATION
               (Exact Name of Registrant as Specified in Charter)

           DELAWARE                     001-16171               04-3372365
(State or Other Jurisdiction of    (Commission File Number)   (IRS Employer
         Incorporation)                                     Identification No.)

         234 BALLARDVALE STREET
            WILMINGTON, MA                                       01887
 (Address of Principal Executive Offices)                     (Zip Code)

     Registrant's telephone number, including area code: 978-694-9121


Check the appropriate box below if the Form 8-K filing is intended to
simultaneously satisfy the filing obligation of the registrant under any of the
following provisions:

         [ ]  Written communications pursuant to Rule 425 under the Securities
Act (17 CFR 230.425)

         [X] Soliciting material pursuant to Rule 14a-12 under the Exchange Act
(17 CFR 240.14a-12)

         [ ] Pre-commencement communications pursuant to Rule 14d-2(b) under the
Exchange Act (17 CFR 240.14d-2(b))

         [ ] Pre-commencement communications pursuant to Rule 13e-4(c) under the
Exchange Act (17 CFR 240.13e-4(c))






                Section 1 - Registrant's Business and Operations


Item 1.01 Entry into a Material Definitive Agreement.

         As permitted by General Instruction B to the Form 8-K, this Current
Report incorporates by reference the information contained in a previously filed
report relating to an Arrangement Agreement dated as of April 22, 2005 (the
"Arrangement Agreement") by and among Beacon Power Corporation ("Beacon"),
Beacon Acquisition Co., a wholly owned subsidiary of Beacon (the "Subsidiary"),
and NxtPhase T&D Corporation ("NxtPhase"): Form 8-K filed on April 25, 2005
(File No. 001-16171) (the "Previously Filed Report").

         On September 27, 2005, Beacon, the Subsidiary and NxtPhase entered into
a First Amendment to the Arrangement Agreement (the "Amendment"). The
Arrangement Agreement required Beacon to file a registration statement with the
Securities and Exchange Commission registering the shares of Beacon common stock
to be issued to NxtPhase stockholders in connection with the acquisition of
NxtPhase by Beacon. Among other things, the Amendment removes this requirement
and Beacon will instead rely on Section 3(a)(10) of the Securities Act so that
the shares are exempt from registration.

         Beacon obtained the option to acquire NxtPhase from Perseus 2000,
L.L.C. ("Perseus 2000"), the largest shareholder of NxtPhase and an affiliate of
Perseus Capital, L.L.C., the largest stockholder of Beacon. Perseus-affiliated
entities have two directors on the boards of directors of each of Beacon and
NxtPhase. Perseus 2000 obtained the option in connection with the NxtPhase Class
A preferred share financing in November 2004, and assigned that option to Beacon
in April 2005.

         The foregoing description of the Amendment does not purport to be
complete and is qualified in its entirety by reference to the Amendment, which
is filed as Exhibit 2.1 hereto, and is incorporated into this report by
reference.

         Stockholders are urged to read the joint proxy statement regarding the
proposed transaction because it contains important information. Stockholders may
obtain free copies of the joint proxy statement, as well as other filings
containing information about Beacon and NxtPhase, without charge, at the SEC's
Internet site (http://www.sec.gov). These documents may also be obtained for
free from Beacon by directing a request to Beacon Power Corporation, 234
Ballardvale Street, Wilmington, Massachusetts 01887, Attention: Secretary.
Beacon and its directors and executive officers and other members of management
and employees may be deemed to be participants in the solicitation of proxies
from their respective shareholders in respect of the proposed transaction.
Information regarding Beacon's directors and executive officers is available in
Beacon's proxy statement for its 2004 annual meeting of shareholders, which was
filed with the SEC on November 10, 2004. Additional information regarding the
interests of such potential participants is included in the joint proxy
statement and the other relevant documents filed with the SEC.


                  Section 9 - Financial Statements and Exhibits

Item 9.01 Financial Statements and Exhibits.

(c) Exhibits

     2.1    First Amendment to Arrangement Agreement dated as of September 27,
            2005 among Beacon Power Corporation, Beacon Acquisition Co. and
            NxtPhase T&D Corporation.



                                    Signature

         Pursuant to the requirements of the Securities Exchange Act of 1934,
the registrant has duly caused this report to be signed on its behalf by the
undersigned hereunto duly authorized.


                                      BEACON POWER CORPORATION



Date:  September 30, 2005           By:/s/ James M. Spiezio
                                       -------------------------
                                  Name:  James M. Spiezio
                                 Title:  Vice President and Chief Financial
                                         Officer





                                  Exhibit Index

Exhibit No.                Description

   2.1       First Amendment to Arrangement Agreement dated as of September 27,
             2005 among Beacon Power Corporation, Beacon Acquisition Co. and
             NxtPhase T&D Corporation.