Proton Energy Systems, Inc., a subsidiary of Distributed Energy Systems Corp. (Nasdaq: DESC – News) and a leader in hydrogen generation and fuel cell technology and products, announced today the award of a Small Business Innovative Research, or SBIR, Phase II contract from the National Aeronautics and Space Administration, or NASA, for development of lightweight unitized regenerative fuel cell technology for unmanned aerial vehicles. Proton also announced the award of a SBIR Phase I contract from the U.S. Army Missile Defense Agency, or MDA, for development of lightweight regenerative fuel cell technology for high altitude airships.

ADVERTISEMENTThe NASA Phase II contract goal is to demonstrate the feasibility of producing and operating lightweight unitized regenerative fuel cell hardware to meet the needs of aerospace applications. Proton’s regenerative fuel cell design incorporates the Company’s core commercial hydrogen generator technology with a fuel cell design, which is capable of generating its own hydrogen at pressure. Building upon the Phase II work, the ultimate design goal specified by NASA is to fill a need for very high energy density energy storage systems for unmanned aerial vehicles, or UAV, flight platforms. NASA intends for these UAVs to perform missions in the areas of terrestrial observation and earth science.

The goal of the Phase I contract with MDA is to achieve key milestones that demonstrate the possibility of manufacturing lightweight regenerativefuel cell hardware to meet the needs of high altitude airships. The ultimate design goal is to develop and demonstrate a hydrogen/oxygen regenerative fuel cell with lightweight packaging capable of high-pressure hydrogen and oxygen generation and multi-kilowatt power output.

The MDA contract is part of a Department of Defense initiative to develop a lighter than air, high altitude airship Advanced Concept Technology Demonstration, or ACTD, prototype. According to the Missile Defense Agency, this ACTD plans to demonstrate the engineering feasibility and potential military utility of an unmanned, un-tethered, gas filled, solar-powered airship that can fly at 70,000 ft.

Proton’s completion of previous NASA SBIR Phase I and Phase II contracts, as well as its ongoing contract with the Naval Research Laboratory funded by the Defense Advanced Research Projects Agency, or DARPA, facilitated the demonstration of zero-gravity unitized regenerative fuel cell operation as well as the ability to electrolyze water to generate hydrogen and oxygen gases at pressures exceeding 3,000 psi. Proton’s HIPRESS(TM), a solid-state electrolysis cell stack design, made the efficient compression of these gases possible, a key feature in high energy aerospace density applications.

Distributed Energy’s President Walter “Chip” Schroeder commented, “We are delighted that NASA and MDA chose to work with Proton on these advanced technology programs. The objective of these contracts is a new level of weight and performance of our energy storage systems. These advances will have important applications not only in NASA and related military, aerospace, and homeland defense missions, but also ultimately in commercial power quality markets.”

The NASA SBIR Phase II contract award is valued at $599,160 over two years. The award is based on Proton’s progress against key milestones in the SBIR Phase I contract. The MDA SBIR Phase I contract is valued at $69,865 with a 6-month period of performance.

About Proton Energy Systems, Inc.

Proton Energy Systems, Inc. designs, develops, and manufactures Proton Exchange Membrane, or PEM, electrochemical products that it employs in hydrogen generating devices and in regenerative fuel cell systems that function as power generating and energy storage devices. Proton’s HOGEN® hydrogen generators produce hydrogen from electricity and water in a clean and efficient process using its proprietary PEM technology. For more information visit www.protonenergy.com .

About Distributed Energy Systems Corp.

Distributed Energy Systems Corp. (Nasdaq: DESC – News) creates and delivers products and solutions to the emerging decentralized energy marketplace, giving users greater control over their energy cost, quality and reliability. As the parent company of Proton Energy Systems and Northern Power Systems ( www.northernpower.com ), Distributed Energy Systems delivers a combination of practical, ready-today energy solutions and the solid business platforms for capitalizing on the changing energy landscape. For more information visit www.distributed-energy.com .

This press release contains forward-looking statements for purposes of the safe harbor provisions under The Private Securities Litigation Reform Act of 1995. Statements contained herein concerning Proton’s and Distributed Energy’s goals, guidance, revenue projections and other statements that are not statements of historical fact may be deemed to be forward-looking information.

Without limiting the foregoing, words such as “anticipates”, “believes”,
“could”, “estimate”, “expect”, “intend”, “may”, “might”, “should”, “will”, and
“would” and other forms of these words or similar words are intended to
identify forward-looking information. Proton’s and Distributed Energy’s actual
results may differ materially from those indicated by these forward-looking
statements as a result of various important factors. Proton and Distributed
Energy each disclaims any obligation to update these forward-looking
statements. Factors that could cause results to differ materially from those
contained in Proton’s and Distributed Energy’s forward-looking statements
include, but are not limited to, our failure to complete development of our
products, failure of our products to achieve commercial acceptance, our
inability to expand our production facilities, manufacture our products at
commercially acceptable costs or establish distribution relationships, the
impact of competitive products, failure to realize the anticipated benefits of
the Northern merger, and other factors detailed in Proton’s Form 10-Q for
quarter ended September 30, 2003, Distributed Energy’s joint proxy
statement/prospectus dated November 4, 2003, and other filings Distributed
Energy may make from time to time with the SEC.

PROTON®, HOGEN®, UNIGEN®, FUELGEN(TM), HIPRESS(TM) and TRANSFORMING ENERGY(TM) are trademarks or registered trademarks of Proton Energy Systems, Inc.