Exhibit 99


              Environmental Power Corporation's Microgy Subsidiary
                    Commences Construction on Second Project

    PORTSMOUTH, N.H.--(BUSINESS WIRE)--May 20, 2004--Microgy
Cogeneration Systems, Inc., a wholly-owned subsidiary of Environmental
Power Corporation (OTCBB: POWR), announced today that it had commenced
construction on its second anaerobic digester system, pursuant to
Microgy's relationship with Dairyland Power Cooperative. This digester
will be located at and owned by the Wild Rose Dairy of LaFarge,
Wisconsin.
    The Wild Rose project represents the second facility to enter
construction under Microgy's relationship with Dairyland Power
Cooperative, following Microgy's commencement of construction on a
similar project for Five Star Dairy of Elk Mound, Wisconsin earlier
this month. The Wild Rose project, similar to the Five Star digester
system that began construction earlier this month, will use manure
from the farm's dairy operations to create and supply biogas to a
0.775 MW generator. In all, Microgy currently has agreements to
construct five projects of this type.
    Donald A. Livingston, President of Microgy, stated, "The beginning
of construction at Wild Rose demonstrates Microgy's increasing
momentum in the execution of its business plan. As more of these
projects are built and enter service, more farmers will be able to see
and experience first hand the benefits of a Microgy anaerobic digester
system. As more farms begin to enjoy the benefits of a Microgy
digester, we believe neighboring farms will want one."
    "We could not be more pleased with the way that Microgy continues
to grow its business, and starting construction of its second project
is just more evidence of Microgy's progress," Kam Tejwani, President
and Chief Executive Officer of Environmental Power, stated. "Microgy
has ambitious plans to recognize its first product sales revenues this
year, and having two projects in construction brings Microgy closer to
that goal."

    ABOUT ENVIRONMENTAL POWER CORPORATION

    Environmental Power Corporation (OTCBB: POWR) is a leader in
resource management and energy production technologies that serve
multiple socially responsible markets. Its wholly-owned subsidiary,
Microgy Cogeneration Systems, Inc., owns a license to a proprietary
technology to convert manure and food industry wastes into biogas,
providing a waste management solution with the potential to pay for
itself by producing renewable energy and other residual products
valuable to farmers and growers. For more information visit the
company's web site at www.environmentalpower.com.

    CAUTIONARY STATEMENT

    The Private Securities Litigation Reform Act of 1995 (the "Act")
provides a "safe harbor" for forward-looking statements. Certain
statements contained in this press release such as statements
concerning planned projects, statements regarding sales pipeline,
backlog and revenue projections, statements containing the words
"expects," "estimates," "anticipates," "believes," "projects" and
variations thereof, and other statements contained in this press
release regarding matters that are not historical facts are forward
looking statements as such term is defined in the Act. Because such
statements involve risks and uncertainties, actual results may differ
materially from those expressed or implied by such forward-looking
statements. Factors that could cause actual results to differ
materially include, but are not limited to, uncertainties involving
development stage companies, uncertainties regarding project
financing, the lack of binding commitments and the need to negotiate
and execute definitive agreements for the construction and financing
of projects, financing and cash flow requirements and uncertainties,
difficulties involved in developing and executing on a business plan,
difficulties and uncertainties regarding acquisitions, technological
uncertainties, risks relating to managing and integrating acquired
businesses, unpredictable developments (including plant outages and
repair requirements), the difficulty of estimating construction,
development, repair and maintenance costs and timeframes, the
uncertainties involved in estimating insurance and implied warranty
recoveries, if any, the inability to predict the course or outcome of
any negotiations with parties involved with Environmental Power's or
Microgy's projects, uncertainties relating to general economic and
industry conditions, the amount and rate of growth in expenses,
uncertainties relating to government and regulatory policies, the
legal environment, intellectual property issues, the competitive
environment in which Environmental Power and Microgy operate and other
factors, including those described in the Company's Annual Report on
Form 10-K for the year ended December 31, 2003, as well as other
filings with the Securities and Exchange Commission. Readers are
cautioned not to place undue reliance on these forward-looking
statements, which speak only as of the date that they are made.
Environmental Power undertakes no obligation to publicly update or
revise any forward-looking statements, whether as a result of new
information, future events or otherwise.

    CONTACT: Environmental Power Corporation
             Investor Contact:
             Kam Tejwani, 603-431-1780
             ktejwani@environmentalpower.com
             or
             Media Contact:
             Kate Dolan, 603-431-1780
             kdolan@environmentalpower.com