CUSIP No. 29406L201


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

                                  SCHEDULE 13D

                                (AMENDMENT NO. 4)

                    UNDER THE SECURITIES EXCHANGE ACT OF 1934

                         Environmental Power Corporation
                                (Name of Issuer)

                                  Common Stock
                         (Title of Class of Securities)

                                    29406L201
                                 (CUSIP Number)

                              Katy Klinedinst, Esq.
                Greenberg Glusker Fields Claman & Machtinger LLP
                      1900 Avenue of the Stars, Suite 2100
                              Los Angeles, CA 90067
                                 (310) 201-7576

   (Name, Address and Telephone Number of Person Authorized to Receive Notices
                               and Communications)

                               September 10, 2008
             (Date of Event which Requires Filing of this Statement)

If the reporting person has previously filed a statement on Schedule 13G to
report the acquisition that is the subject of this Schedule 13D, and is filing
this schedule because of Sections 240.13d-1(e), 240.13d-1(f) or 240.13d-1(g),
check the following box / /.

NOTE: Schedules filed in paper format shall include a signed original and five
copies of the schedule, including all exhibits. See Section 240.13d-7(b) for
other parties to whom copies are to be sent.

* The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).


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CUSIP No. 29406L201

(1)      Name of Reporting Person
         S.S. or I.R.S. Identification No. of Above Person

         David Gelbaum, Trustee, The Quercus Trust

(2)      Check the Appropriate Box if a Member of a Group (See Instructions)
                                                                    (A)      /X/
                                                                    (B)      / /
(3)      SEC Use Only

(4)      Source of Funds (See Instructions)

         PF

(5)      Check if Disclosure of Legal Proceedings is Required Pursuant to Items
         2(d) or 2(e)                                                        / /

(6)      Citizenship or Place of Organization

         U.S.

                           (7)     Sole Voting Power
                                   -0-

Number of Shares           (8)     Shared Voting Power
Beneficially Owned                 -0-
by Each Reporting
Person With                (9)     Sole Dispositive Power
                                   -0-

                           (10)    Shared Dispositive Power
                                   -0-

(11)     Aggregate Amount Beneficially Owned by Each Reporting Person
         -0-

(12)     Check if the Aggregate Amount in Row (11) Excludes Certain Shares
         (See Instructions)                                                  / /

(13)     Percent of Class Represented by Amount in Row (11)
         0%

(14)     Type of Reporting Person (See Instructions)
         IN


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CUSIP No. 29406L201

(1)      Name of Reporting Person
         S.S. or I.R.S. Identification No. of Above Person

         Monica Chavez Gelbaum, Trustee, The Quercus Trust

(2)      Check the Appropriate Box if a Member of a Group (See Instructions)
                                                                    (A)      /X/
                                                                    (B)      / /
(3)      SEC Use Only

(4)      Source of Funds (See Instructions)

         PF

(5)      Check if Disclosure of Legal Proceedings is Required Pursuant to Items
         2(d) or 2(e)                                                        / /

(6)      Citizenship or Place of Organization

         U.S.

                           (7)     Sole Voting Power
                                   -0-

Number of Shares           (8)     Shared Voting Power
Beneficially Owned                 -0-
by Each Reporting
Person With                (9)     Sole Dispositive Power
                                   -0-

                           (10)    Shared Dispositive Power
                                   -0-

(11)     Aggregate Amount Beneficially Owned by Each Reporting Person
         -0-

(12)     Check if the Aggregate Amount in Row (11) Excludes Certain Shares
         (See Instructions)                                                  / /

(13)     Percent of Class Represented by Amount in Row (11)
         0%

(14)     Type of Reporting Person (See Instructions)
         IN


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CUSIP No. 29406L201

(1)      Name of Reporting Person
         S.S. or I.R.S. Identification No. of Above Person

         The Quercus Trust

(2)      Check the Appropriate Box if a Member of a Group (See Instructions)
                                                                    (A)      /X/
                                                                    (B)      / /
(3)      SEC Use Only

(4)      Source of Funds (See Instructions)

         PF

(5)      Check if Disclosure of Legal Proceedings is Required Pursuant to Items
         2(d) or 2(e)                                                        / /

(6)      Citizenship or Place of Organization

         U.S.

                           (7)     Sole Voting Power
                                   -0-

Number of Shares           (8)     Shared Voting Power
Beneficially Owned                 -0-
by Each Reporting
Person With                (9)     Sole Dispositive Power
                                   -0-

                           (10)    Shared Dispositive Power
                                   -0-

(11)     Aggregate Amount Beneficially Owned by Each Reporting Person
         -0-

(12)     Check if the Aggregate Amount in Row (11) Excludes Certain Shares
         (See Instructions)                                                  / /

(13)     Percent of Class Represented by Amount in Row (11)
         0%

(14)     Type of Reporting Person (See Instructions)
         OO


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CUSIP No. 29406L201


Item 1.

         This Amendment No. 4 to Schedule 13D (this "Amendment No. 4") amends
and restates, where indicated, the statement on the initial Schedule 13D
relating to the Common Stock of the Issuer filed by The Quercus Trust, David
Gelbaum and Monica Chavez Gelbaum (the "Reporting Persons") with the Securities
and Exchange Commission on August 31, 2007 and prior amendments thereto (the
"Prior Schedule 13Ds"). Capitalized terms used in this Amendment No. 4 but not
otherwise defined herein have the meanings given to them in the Prior Schedule
13Ds.

         This Amendment No. 4 is being made to disclose the disposition of
additional shares (the "Shares") of Common Stock of the Issuer. Except as
otherwise set forth herein, this Amendment No. 4 does not modify any of the
information previously reported by the Reporting Persons in the Prior Schedule
13Ds.

Item 5.  Interest in Securities of the Issuer

         (a) As of the date of this Amendment No. 4, the Reporting Persons
beneficially own no shares of Common Stock.

         (b) Each of David Gelbaum and Monica Chavez Gelbaum, acting alone, had
the power to exercise voting and investment control over the shares of Common
Stock previously owned by the Trust.

         (c) Since September 7, 2008, the Reporting Persons have sold shares of
Common Stock in brokered transactions as follows:

            Date               Number of Shares          Price Per Share
            ----               ----------------          ---------------
          8/7/2008                  (7,128)                 $ 3.9200
          8/8/2008                  (3,614)                 $ 3.9100
         8/11/2008                  (5,600)                 $ 3.6300
         8/12/2008                  (2,300)                 $ 3.6300
         8/13/2008                  (4,900)                 $ 3.8200
         8/14/2008                  (1,300)                 $ 3.6100
         8/15/2008                  (1,500)                 $ 3.6100
         8/18/2008                  (1,600)                 $ 3.5100
         8/19/2008                  (3,700)                 $ 3.3400
         8/20/2008                  (3,700)                 $ 3.3400
         8/21/2008                  (2,300)                 $ 3.3200
         8/22/2008                 (15,471)                 $ 3.3100
         9/10/2008                 (791,856)                $ 1.7000

         (d) Not applicable.

         (e) The Reporting Persons ceased to be the beneficial owners of more
than five percent of Issuer's Common Stock on September 10, 2008.

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CUSIP No. 29406L201


Item 6.  Contracts, Arrangements, Understandings or Relationships With
         Respect to Securities of the Issuer

         Pursuant to the Power of Attorney filed as Exhibit "B" to Amendment No.
4 to Schedule 13D filed on August 24, 2007 with respect to the issuer Emcore
Corp., David Gelbaum has been appointed as Monica Chavez Gelbaum's
Attorney-In-Fact.

Item 7.  Material to Be Filed as Exhibits

         Exhibit A:  Agreement Regarding Joint Filing of Amendment No. 4 to
                     Schedule 13D.


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CUSIP No. 29406L201


SIGNATURE

         After reasonable inquiry and to the best of its knowledge and belief,
each of the undersigned certifies that the information set forth in this
statement is true, complete and correct and agrees that this statement may be
filed jointly with the other undersigned parties.


Dated:  September 16, 2008       /s/ David Gelbaum
                                 -----------------------------------------------
                                 David Gelbaum, Co-Trustee of The Quercus Trust


                                 /s/ David Gelbaum, as Attorney-In-Fact for
                                     Monica Chavez Gelbaum
                                 -----------------------------------------------
                                 Monica Chavez Gelbaum, Co-Trustee of The
                                 Quercus Trust


                                 /s/ David Gelbaum
                                 -----------------------------------------------
                                 The Quercus Trust, David Gelbaum, Co-Trustee of
                                 The Quercus Trust


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CUSIP No. 29406L201


                                    EXHIBIT A

       AGREEMENT REGARDING JOINT FILING OF AMENDMENT NO. 4 TO SCHEDULE 13D
       -------------------------------------------------------------------

         The undersigned agree that the Amendment No. 4 to Schedule 13D with
respect to the Common Stock of Environmental Power Corporation is a joint filing
being made on their behalf.


Dated:  September 16, 2008       /s/ David Gelbaum
                                 -----------------------------------------------
                                 David Gelbaum, Co-Trustee of The Quercus Trust


                                 /s/ David Gelbaum, as Attorney-In-Fact for
                                     Monica Chavez Gelbaum
                                 -----------------------------------------------
                                 Monica Chavez Gelbaum, Co-Trustee of The
                                 Quercus Trust


                                 /s/ David Gelbaum
                                 -----------------------------------------------
                                 The Quercus Trust, David Gelbaum, Co-Trustee of
                                 The Quercus Trust


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