Siemens Hits Major Milestone in SECA Solid Oxide Fuel Cell Program; No Degradation After 1,500 Hours
|Siemens’ high power density (HPD) planar design (top right) compared to its existing tubular cell design ( top left). Next-generation HPD Delta 9 design at bottom. Click to enlarge.|
Siemens Power Generation announced the successful testing of its latest solid oxide fuel cell (SOFC) technology that incorporates its high-power density technology being developed under the US Department of Energy’s (DOE) Solid State Energy Conversion Alliance (SECA).
In August 2002, under the SECA program, Siemens Power Generation entered into an $80 million cooperative agreement with DOE’s National Energy Technology Laboratory to develop low-cost Solid Oxide Fuel Cell (SOFC) power systems for residential, automotive and military applications.
Under the agreement, entitled “Small-scale, Low-cost SOFC Systems,” Siemens Power Generation was to develop a new seal-less planar SOFC system.
A prototype 5 kW-class complete system using the SECA technology has operated for 2,800 hours and continues to operate at the Siemens facility near Pittsburgh, PA. It has met or exceeded all of the DOE technical and economic objectives for Phase 1 of the SECA program.
The successful operation of the SECA system is especially noteworthy in that there has been absolutely no degradation of cell or system performance during the period of operation, according to Siemens. With lifetime a key factor in the commercialization of fuel cells, Siemens asserts that its program is the only SECA program to have achieved no cell degradation during extended operation.
A Delphi SOFC system for application in an on-board auxiliary power unit (APU) in vehicles that achieved Phase 1 goals earlier this year, for example, experienced power degradation of 7% over 1,500 hours of operation. (Earlier post.)
While the test duration required by the DOE was 1,500 hours, the system continues to be operated to determine lifetime, peak power and efficiency potential as the performance of the cells improve. They will also be put through further tests in the coming months to assess the robustness of the new stack technology.
Siemens’ new high power density cells are a further development of its tubular cell design and represent a significant step forward towards commercialization of SOFC systems. This new technology has already demonstrated volumetric power density four times greater than the tubular cells, which translates into significantly reduced volume and reduced cost per kW. A number of configurations have already been tested, and further development and tests are planned to qualify the optimum system configurations.
In a tubular SOFC design, air flows through the interior of the cell, and fuel flows on the outside of the cell. At elevated temperatures, the oxygen in the air ionizes and the resulting ions flow through the electrolyte and combine with the fuel on the cell’s exterior. This is an electrochemical reaction, so electrons are released. With proper connections, they can flow through an external circuit as electricity.
The program will be executed in three phases over a ten-year period, and at the end of each phase a prototype SOFC system in the 3-10 kW range will be tested for one or more of the targeted applications. Specific cost targets for each phase will be addressed with the ultimate program target being $ 400/kW in high volume production.
The SECA Phase 1 prototype system test has exceeded our expectations and clearly shows we can successfully enhance our proven SOFC technology for higher performance and lower cost. As we move forward, we are examining various cell designs that substantially increase cell power, stack power density and module simplifications, and results to date have been outstanding.—Thomas Flower, president of Siemens’ Stationary Fuel Cells division
Recently, Siemens implemented a number of design, material and process changes, and this latest SECA system test validates new manufacturing processes intended to enhance reliability and reduce cost. The next steps are to continue to develop the high power density technology as part of a program that merges the subsequent phases of the SECA program with DOE’s coal-based fuel cell systems program. The ultimate objective of this program is for SOFCs to provide clean power fueled by syngas from domestic coal resources as part of DOE’s FutureGen program.
Siemens plans to commercialize SOFC generators and systems in the 5 kW to multi-megawatt range, with pre-commercial deliveries in the 2006/2009 time frame depending on rating. Siemens is developing SOFC technology under cooperative agreements with the US Department of Energy, through its National Energy Technology Laboratory and the German Federal Ministry of Economics and Technology.
SECA Program Review—Siemens (Sep 2006)