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19. Advancements in Solid Oxide Fuel Cell BALANCE-OF-PLANT and TURBINE PERFORMANCE AND SUB-SYSTEMS FOR PERFORMANCE ENHANCEMENTS

The goal of the DOE-sponsored Solid State Energy Conversion Alliance (SECA) is to develop commercially-viable ($400/kW) solid oxide fuel cell (SOFC) power generation systems by the year 2010. SOFC-based systems are attractive alternatives to current technologies in large-scale stationary applications - SECA is ahead of schedule in developing these systems for FutureGen, the world’s cleanest coal-based power plant. SOFC systems are very efficient, from 40 to 60 percent (depending on system size) and up to 85 percent in large co-generation applications. In addition, the electrochemical conversion in a SOFC takes place at a lower temperature (650ºC to 850ºC) than combustion-based technologies, resulting in decreased emissions, particularly nitrogen oxides.

The Office of Fossil Energy fuel cell program is focused on delivering systems to FutureGen after successfully reducing system cost. In order to achieve SECA program cost targets, small scale spin-off applications requiring diesel fuel will begin in 2010. The subtopics in this topic seek to develop the diesel fuel processing technology necessary for these spin-off applications, as well as novel power electronics topologies for large-scale stationary applications. Grant applications are sought to address these areas described below in subtopics a and b.

Research and development to explore turbine components and sub-systems for performance enhancements is also sought. Low heating values typical of syngas and the injection of diluents (to control combustion temperatures and therefore thermal NO_x formation) have resulted in higher mass flows (~14%) through the turbine hot section of integrated gasification combined cycle ( IGCC) turbines than for the same model turbines operated with natural gas. This produces 20-25% higher turbine power compared to natural gas but also tends to increase the heat transfer to the hot section vanes and blades. Where steam is used as a diluent to control NOx, the higher heat transfer properties for steam compared to air also further tends to increase the heat load to hot section components. Accordingly, current IGCC turbines have been operated at reduced firing temperatures to maintain hot gas parts at temperatures similar to those of the same model turbines operated with natural gas. The progression from current syngas to high hydrogen fuels produced from coal syngas and oxy-fuels along with the usual increase in turbine inlet temperature through time to increase performance (power and efficiency) will produce additional heat loads and aerodynamic/cooling requirements for hot section components. Grant applications are sought to address these areas described below in subtopics c and d.

a. 1 to 5 kWe Diesel Reformer—Grant A applications are sought to: develop and test a new and novel integrated diesel fuel processing solution for SOFC-based auxiliary power units (APUs). APUs for Class 8 diesel trucks and recreational vehicles are strong early market for SOFC systems – by providing on-board power while the vehicle engine is off, SOFC-based APUs address the challenges presented by anti-idling legislation enacted in many states. The choice of fuels for these applications will focus on diesel liquid fuels because of their availability, low cost and existing distribution networks. Diesel must be reformed in order to achieve the desired gas compositions (consisting of hydrogen, carbon monoxide, and moderate levels of methane (< 10 mole %), required for acceptable SOFC electrochemical performance. Therefore, grant applications are sought to design, fabricate, and test low-cost, compact, and reliable integrated diesel fuel reformers for these applications. For any new design, cost, manufacturability, and reliability are critical factors in meeting SECA program goals.

The reformer may be based upon plasma-assisted partial oxidation, catalytic partial oxidation or autothermal reforming ( ATR ) technologies. Designs must explicitly address and include the diesel injection system, mixing chamber, reactor vessel, and reaction media. Additional design requirements include: (1) operation within the temperature range 600 to 1000 °C; (2) turndown capability maximized - not less than 4 to 1; (3) pressure drops below 1 psi, throughout the device; (4) minimal water usage, consistent with water recovery from the fuel cell anode or other point within the process; (5) maximum carbon suppression; and (6) a volume of less than 10 L. In addition, practical SOFC APU system applications require fast start-up, processed fuel reformate availability to accommodate power demand transients, and the ability to accommodate part-load operation – all with minimal hydrocarbon (preferably methane) slip. Finally, the diesel reformer catalyst itself must be able to handle up to 50 ppmv of sulfur in the fuel without sulfur poisoning and provide stable, long-term operation (> 5,000 hours) before maintenance is required.

Phase I work shall center upon a systems analysis and preliminary reformer design for the intended application. In addition, a detailed cost analysis shall be performed, assuming an annual production volume of 80,000 units. If selected for Phase II, the recipient shall fabricate and test the unit to demonstrate suitability to the intended application.

Questions – contact Dave Berry (david.berry@netl.doe.gov)

b. Evolved Designs for High-Power, Low Cost, High Performance Fuel Cell Power Conditioning Systems—Research is currently underway within the SECA program to develop and demonstrate fuel cell technologies that can support power systems with capacities of 100 megawatts or more in central power stations utilizing gasified coal. These systems much achieve at least 50% overall higher heating value (HHV) efficiency in converting the energy in coal to grid power, capture 90% or more of the systems CO₂ emissions, and be capable of being manufactured at a cost of $400 per kilowatt, exclusive of the coal gasification unit and CO₂ separation subsystems.

Grant applications are sought to: identify new topologies that will reduce capital and life cycle costs, increase efficiency, improve reliability, and improve serviceability of power conditioning systems for future large-scale, central station fuel cell systems capable of providing electricity to the power grid at the transmission circuit level. The boundary conditions for the research are to convert the 300 to 800 V DC output from fuel cell modules to transmission level voltage (300 to 500 kV AC) where the net delivered plant power is 300 MW, and each fuel cell module is a few hundred kW in generation capacity.

Research has demonstrated that simulated evolution can reconfigure, adapt, and design electronic structures in an automated manner. Applications include both analog and digital circuitry design using Genetic algorithms (Gas), which are stochastic parallel search algorithms used to search large, non-linear search spaces where expert knowledge is difficult or lacking.

Power conditioning topologies that may be considered include commercially available step-up transformers, high frequency versus low frequency systems, converters with few stages versus multi-stages, high voltage versus low voltage inverters, and power converters for individual fuel cell modules versus multiple modules. Advanced component technologies that may be considered include advanced semiconductor devices made with the SiC material, advanced nano-crystalline magnetic materials for filters and transformers, as well as advanced cooling system and capacitor technologies. This subtopic seeks novel approaches to apply Genetic algorithms to evolve designs for high-power, low-cost, high-performance fuel cell power conditioning topologies that aggregate multiple fuel cell modules for central power station service. STTR applications are encouraged for this subtopic.

Questions – contact Don Collins (donald.collins@netl.doe.gov)

c. Innovative Cooling Approaches—Grant applications are sought for: research and development to explore innovative cooling approaches that allows ceramic and metal turbine parts to survive in working fluids with higher temperatures. Research is needed to explore innovative cooling approaches and/or increased film-cooling effectiveness to improve component durability while also decreasing sensitivity to potential surface roughness effects or propensity to collect deposits in and around cooling hole exits. Experiments to evaluate and demonstrate these approaches and their benefits are desirable. Effects on cooling effectiveness should be at least analytically evaluated for a range of flow path heat transfer properties (e.g., resulting from different water vapor levels) associated with coal syngas, high hydrogen fuels derived from syngas, and oxy-fuels. Candidate cooling approaches to be explored should be first discussed with turbine suppliers to consider their manufacturability. Future power plants using coal gasification, combined cycles or oxy-fuel cycles that are targeting efficiencies greater than 50% and the associated higher firing temperature will require new advanced cooling technologies. By using closed loop steam cooling in place of compressor discharge air, the current H series gas turbines are able to increase their inlet temperatures (a.k.a. firing temperature) from approximately 1260ºC (2300ºF) to around 1427ºC (2600ºF) and better use of available compressor air. Systems studies have shown that the current state of the art turbine inlet temperature of around 1427ºC (2600ºF) may need to be raised even higher in order to meet the long term Turbine Program efficiency goals. The challenge is to find new, novel, and more effective cooling solutions for the hottest sections of the turbine including the combustor, reheater, transition section, 1st stage nozzle, stators, rotor blades and disks. Preferably, such new methods should not increase the manufacturing costs significantly. One example of such an innovative active cooling concept is transpiration cooling. Transpiration cooling, made possible in part through platelet technology has allowed very high heat flux rocket engines and missile re-entry nose cones to be deployed. Platelet technology has proven to be highly successful for meeting these challenging high heat flux cooling requirements. This subtopic solicits grant applications for advanced cooling technology (such as, but not limited to platelet technology).

Questions - contact Rondle Harp (rondle.harp@netl.doe.gov)

d. Increasing Performance of Gas Turbine Exhaust Systems—Grant applications are sought for: research and development that mitigate or reduce turbine exhaust (diffuser) pressure losses from the increased volumetric flow. An increase in the power extracted by the turbine can be achieved by an increase of the pressure at the inlet plane of the turbine, or by a decrease of the back pressure at the exit plane of the turbine, or both. Most approaches for improving turbine performance address the first option, for example increasing the pressure ratio of the compressor and therefore the combustor pressure and the combustor temperature. Other approaches seek to improve the high-temperature components: materials, coatings, corrosion resistance, and high-temperature bearings. Raising peak temperatures, however, increase NO_x production, require expensive metallurgy, and reduce service life. This subtopic seeks grant applications to increase the power extraction of a gas turbine by lowering the back pressure at the exit plane of gas turbines, which would allow for reductions in heat rate, peak temperature, and fuel consumption while maintaining rated power, or increase power at constant heat rate, or both, yielding greater operational flexibility. In addition, DOE’s research indicates that gas turbines operated with syngas and hydrogen fuels from coal gasification will have a higher volumetric flow than equivalent oil or natural gas-fired turbines.

Questions - contact Rondle Harp (rondle.harp@netl.doe.gov)

References:

Subtopic a: 1 to 5 kWe Diesel Reformer

1. Hartmann, L., et al., “Cool Flame Evaporation for Diesel Reforming Technology,” Proceedings of the 8th International Symposium on Solid Oxide Fuel Cells: SOFC VIII, 8:1250, Pennington, NJ: The Electrochemical Society, Inc., 2001. (ISBN: 1-56677-377-6)

2. “Solid State Energy Conversion Alliance (SECA),” U.S. DOE NETL Website. (URL: http://www.netl.doe.gov/seca/. Provides information on SECA SOFC development goals and status as well as conferences, meetings and individual fuel processing projects)

3. Ahmed, S. and Krumpelt, M., "Hydrogen from Hydrocarbon Fuels for Fuel Cells," International Journal of Hydrogen Energy, 26:291, April 2001. (Abstract and ordering information available at: http://www.sciencedirect.com/science?_ob=IssueURL&_tockey=%23TOC%235729%232001%23999739995%23242329%23FLA%23&_auth=y&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=0d290a23eda9faee837c4f3c50df193d)

4. Flytzani-Stephanopoulos, M. and Voecks, G. E., “Autothermal Reforming of Aliphatic and Aromatic Hydrocarbon Liquids,” International Journal of Hydrogen Energy, 8:539, 1983. (Abstract and ordering information available at: http://www.sciencedirect.com/science?_ob=IssueURL&_tockey=%23TOC%235729%231983%23999919992%23446991%23FLP%23&_auth=y&view=c&_acct=C000050221&_version=1&_urlVersion=0&_userid=10&md5=8fb106484a517475339a146a4ad722c7)

Subtopic b: Evolved Designs for High-Power, Low Cost, High Performance Fuel Cell Power Conditioning Systems

5. Stoica, A., et al., “Silicon Validation of Evolution-Designed Circuits,” IEEE Proceedings: Computers and Digital Techniques, Special Issue on Evolvable Hardware, 151(4): 265-266, July 2004. (Full text available at: http://ehw.jpl.nasa.gov/Documents/PDFs/SiliconValidation.pdf)

6. Stefatos, E. F., et al., “An EHW Architecture for the Design of Unconstrained Low-Power FIR Filters for Sensor Controlling Using Custom-Reconfigurable Technology,” Proceedings of the 2005 NASA/DoD Evolvable Hardware Conference, Washington, DC, June 2005, IEEE Computer Press, June 2005. (Full text available at: http://ehw.jpl.nasa.gov/Documents/PDFs/EHW%20Architecture.pdf)

7. Lohn, J., D. et al., Proceedings of the 2005 NASA/DoD Evolvable Hardware Conference, Washington, DC, June 2005, IEEE Computer Press, June 2005. (ISBN: 0-7695-2399-4)

8. Ozpineci, B. et al., “Trade Study on Aggregation of Multiple 10-kW Solid Oxide Fuel Cell Power Modules,” Technical Report, Oak Ridge National Laboratory, November 29, 2004 . (Report No. ORNL/TM-2004/248) (Full Text Available at: http://www.ornl.gov/~webworks/cppr/y2001/rpt/121814.pdf)

9. Zebulum, R., et al., “High Temperature Experiments for Circuit Self-Recovery,” Proceedings of the 2004 NASA/DoD Conference on Evolvable Hardware, IEEE Computer Press, June 2004. (Full Text Available at: http://ehw.jpl.nasa.gov/Documents/PDFs/publications%20pdf/CameraReadyKeymeulen.pdf)

10. Lohn, J., et al., Proceedings of the 2003 NASA/DoD Conference on Evolvable Hardware, IEEE Computer Press, July 2003. (ISBN: 0-7965-1977-6)

11. Zebulum, R. S., et al., “Evolutionary Electronics: Automatic Design of Electronic Circuits and Systems by Genetic Algorithms,” CRC Press, December 2001. (ISBN: 0849308658)

12. Torrero, E., et al., “1 MW Fuel Cell Project, Test and Evaluation of Five 200 kW Phosphoric Acid Fuel Cell Units Configured as a 1 MW Power Plant,” National Rural Electric Cooperative Association/US Department of Defense/EPRI (Electric Power Research Institute), July 2002. (Report No. 1007014) (Publisher’s summary available at: http://www.epri.com/OrderableitemDesc.asp?product_id=000000000001007014&targetnid=270688&value=05T101.0&marketnid=0&oitype=1&searchdate=7/10/2002 )

Subtopic c: Innovative Cooling Approaches

13. Chiesa, P. and Macchi, E., “A Thermodynamic Analysis of Different Options to Break 60% Electrical Efficiency in Combined Cycle Power Plants,” American Society of Mechanical Engineers (ASME) Journal of Engineering for Gas Turbines and Power, 126: 770- 785, October 2004. (Abstract and ordering information available at: http://scitation.aip.org/ASMEJournals/GasTurbinesPower/. Browse All Issues January 200-Present for volume and page number, above.)

14. Ito, S., et al., “Conceptual Design and Cooling Blade Development of 1700ºC Class High-Temperature Gas Turbine,” ASME Journal of Engineering for Gas Turbines and Power, 127: 358- 368, April 2005. (Abstract and ordering information available at: http://scitation.aip.org/ASMEJournals/GasTurbinesPower/. Browse All Issues January 200-Present for volume and page number, above.)

15. Muenggenburg, H. H., et al., “Platelet Actively Cooled Thermal Management Devices”, presented at AIAA/SAE/ASME/ASEE* 28th Joint Propulsion Conference and Exhibit, Nashville , TN , July 6-8, 1992 , American Institute of Aeronautics and Astronautics, 1992. (Product No. AIAA-1992-3127) (First page, with abstract, available at: http://www.aiaa.org/content.cfm?pageid=406&gTable=mtgpaper&gID=73550)

Subtopic d: Increasing Performance of Gas Turbine Exhaust Systems

16. Fonda, P. and Bonardi, P., "Application of an Efficient Subsonic Diffuser to a Gas Turbine Engine," Proceedings of ASME Fluids Engineering Division Summer Meeting - FEDSM97, Vancouver, Canada, June 22-26, 1997, July 1997. (ISBN: 0791812375)

17. “Five-Year Investment Plan, 2002-2006 for the Public Interest Energy Research (PIER) Plan,” Vol. 1, California Energy Commission, March 2001. (Full text available at http://www.energy.ca.gov/reports/2001-03-02_600-01-004A.PDF. If you cannot access the document via this link, you may request a copy from Rondle Harp at RONDLE.HARP@NETL.DOE.GOV.)

18. Fonda P., and Bonardi, P., “Short Subsonic Diffuser for Large Pressure Ratios,” June 1977. (U.S. Patent No. 4,029,430) (Full text available at: http://www.uspto.gov/. Under “Patents” on menu at left, click on “Search”. Under “Issued Patents” click on “Quick Search”. Search by Patent No. above.)

19. Fonda P., and Bonardi, P., “[Efficient Subsonic] Diffuser,” February 1997. (U.S. Patent No. 5,603,605) (Full text available at: http://www.uspto.gov/. Under “Patents” on menu at left, click on “Search”. Under “Issued Patents” click on “Quick Search”. Search by Patent No. above.)

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* American Institute of Aeronautics and Astronautics/ Society of Automotive Engineers/American Society of Mechanical Engineers/American Society for Engineering Education.

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