Siemens Westinghouse Systems

Since 1986, Siemens Westinghouse has tested at least 12 fully integrated SOFC systems on customer sites, ranging from 0.4 kW to 220 kW [47]. The most recent demonstrations were a 100 kW atmospheric SOFC system, operated in Westervoort, the Netherlands, by a consortium of Dutch and Danish energy companies and a 220 kW SOFC/GT hybrid system, installed and tested at the National Fuel Cell Research Center on the campus of the University of California-Irvine for Southern California Edison [48-51]. These two systems are discussed below. 

---

Figure 12.18 Example of SOFC geometries, (a) Tubular geometry ofthe Siemens-Westinghouse system (b) Planar structure ofthe Sulzer-Hexis SOFC (for details, see the text).

Siemens Westinghouse Power Corporation (SWPC) has three TSOFC systems employing tubular cell technology operating on user sites. All were produced in their Pittsburgh, Pennsylvania facility. The capacities of the systems are 220 kilowatts, 100 kilowatts, and 25 kilowatts. 

Siemens Westinghouse is planning a number of tests on power plants that are prototypes of future products. All systems employ the tubular SOFC concept and most are combined with gas turbines in a hybrid configuration. Capacities of these systems are 250 kilowatts atmospheric, 300 kilowatt class hybrid, and 1 megawatt class hybrid. They are to operate at various sites in the U.S., Canada, and Europe. Some of them are discussed below. 

This natural gas fuel cell power system is based on a pressurized TSOFC combined with a combustion turbine developed by Siemens Westinghouse (52). Most TSOFC power plant concepts developed to date have been based on atmospheric operation. However, as shown in... 

Siemens Westinghouse provided TSOFC performance values for the HP and LP conditions, which Parsons incorporated into the systems analysis. 

Figure 9-23 Diagram of a proposed Siemens-Westinghouse hybrid system (Taken from DOE Project Fact Sheet - Fuel Cell/ATS Hybrid Systems)...

Siemens-Westinghouse Power Corporation, of Pittsburgh, PA, with a subcontract to Allison Engine Company, evaluated a pressurized solid oxide fuel cell coupled with conventional gas turbine technology without a steam plant. The system was operated at a pressure of 7 atm. The fuel cell generated 16 MW of power and the gas turbine generated 4 MW of power. The process showed 67 % efficiency as developed. An efficiency of 70 % is deemed achievable with improvement in component design. The COE is predicted to be comparable to present day alternatives. NOx levels were less than 1 ppm. 

Siemens-Westinghouse Power Corporation, Pittsburgh, PA, and Solar Turbines developed a conceptual design of an economically and technically feasible 20-MW, 70-% efficient natural gas-fueled power system that employs solid oxide fuel cells operating at elevated pressure in conjunction with an Advanced Turbine System gas turbine. The fuel cell, operated at 9 atm pressure, generated 11 MW of power. Two Solar Mercury 50 gas turbines were used to generate 9 MW of power. The results of the study indicated a system efficiency near 60 %. A low COE relative to conventional power generation is predicted. 

Siemens-Westinghouse Power Corporation of Pittsburgh, PA developed and fabricated the first advanced power plant to combine a solid oxide fuel cell and a gas turbine. The microturbine generator was manufactured by Northern Research and Engineering Corporation of Woburn, Mass. The factory acceptance test was completed in April 2000. Southern California Edison will operate the new hybrid plant at The National Fuel Cell Research Center at the University of California-Irvine. A year of testing in a commercial setting will be performed at this site. The system cycle is expected to generate electric power at 55 % efficiency. 

A 320-kilowatt hybrid system is also in the planning stages. An initial commercial offering of a one MW fuel cell-microturbine power plant in late 2002 will be the end results of this Department of Energy/Siemens Westinghouse partnership program (70). 

Demonstration highlight The world s largest SOFC system, a 100 kW Siemens-Westinghouse SOFC installed at a Dutch cogeneration plant in 1998. 

Policy Studies on infrastructure considerations and transition management activities include (a) Fuel Cell RD D activities (b) SOFC and PEMFC cells, stacks, systems are being developed in relation to local generation (c) Systems field testing is being undertaken by Siemens-Westinghouse, Sulzer, and Plug-Power. 

Fieldtesting 100 kWe SOFC system (Siemens-Westinghouse). The 100 kW SOFC CHP test unit was installed at a Dutch cogeneration plant in 1998, as one of several units to be tested in the joint government-industry development effort. The test is being carried out at the local utility in Westervoort by NUON, which operates the system for EDB/Elsam. Funding for the... 

Unlike molten carbonates, solid oxides use a hard ceramic electrolyte instead of a liquid. That means the fuel cell can be cast into a variety of useful shapes, such as tubes. With higher temperatures, sofcs may be able to cogenerate steam at temperatures as high as i,ooo°f. The Siemens Westinghouse Power Corporation has built the first advanced hybrid system, which combines a gas turbine with a tubular sofc. As of 2003, the 220 kW hybrid system has operated in California for more than 2,000 hours with a respectable 53 percent efficiency, comparable to current combined cycle gas turbines. The ultimate goal is an efficiency of 70 percent or more. 

Siemens Westinghouse is advanced in its pursuit of gas turbine integration. High-temperature depleted air and unused fuel from the fuel cell cannot be discarded, and are best used in a gas turbine, as outlined in Baozhen Li etal. (2001), the Siemens patent for a Single Module Pressurised Fuel Cell Turbine Generator System (pp. 974-979). The effect... 

NGK Insulators in Japan had a patent for a system closely resembling that of Siemens Westinghouse. NGK Insulators has sold out to Mitsubishi, and dropped out of the fuel cell business, an interesting piece of history. 

Fig. 7. Solid oxide fuel cell configurations. A Siemens-Westinghouse tubular cell B Tubular integrated interconnector concept. Similar interconnected systems exist in planar geometry C Planar SOFC designs, differing only in gas flow manifolding.

Kabs, H. Advanced SOFC Technology and its Realization at Siemens Westinghouse , Bilateral Seminars 33, Materials and Processes for Advanced Technology Materials for Energy Systems, Egyptian-German Workshop, Cairo 7.-9. April 2002, ISBN 3-89336-320-3, edited by D.Stover, M.Bram, (2002), 91-101... 

From the structure point of view, there are two types of structures of SOFC tubular and planar. Tubular SOFCs have shown some desirable characteristics over systems with planar SOFCs [4]. Tubular SOFCs can alleviate the sealing problem arose by CTE mismatch of planar SOFC therefore, they are robust for repeated cycling under rapid changes in electrical load and in cell operating temperatures. The large form factor tubular SOFC built by Siemens Westinghouse has successfully conducted long-term operation over 70,000 h. Small-scale tubular SOFCs could... 

Candle filters have in general proved highly efficient, even for very fine particles of sizes down to the order of 1 pm. However, a number of problems remain to be solved, such as the build-up of dust cake on the filters leading to occasional cake bridging between candles, filter failure and breakage. A number of hot gas filtration systems have been developed and tested under industrially relevant conditions an advanced particle filter (APF) containing 284 candles was installed at the 70 MW (electric) Tidd PFBC demonstration plant at Brilliant, Ohio gas flow and particle deposition have been modelled by Ahmadi and Smith [53] for the Tidd filter vessel and by Mazaheri and Ahmadi [54] for the Siemens-Westinghouse particulate control device (PCD). 

Kabs H., Operational Experience with Siemens-Westinghouse SOFC Cogeneration Systems, Proceedings of Lucerne Fuel Cell Forum 2001, Lucerne (Switzerland), 2001. 

Siemens Westinghouse Power Corporation (2000) Pressurized solid oxide fuel cell/gas turbine power system. Contract DE-AC26-98FT40355, Final Report, US Department of Energy, Office of Scientific and Technical Information, Oak Ridge, TN. 

Siemens Westinghouse also produced a 220 kW pressurized SOFC/gas turbine hybrid system, which was installed and tested at the National Fuel Cell Research Center on the campus of the University of Califomia-Irvine (USA). This system was the world s first demonstration of a pressurized SOFC generator coupled with a microturbine generator. The system accumulated nearly 3,400 h of run-time while operating at a calculated net AC electrical efficiency of 53 %. Analysis indicates that with such systems in large MW sizes, an electrical efficiency of 70 % is achievable. 

Solid Oxide Fuel Cells, History, Fig. 6 Siemens Westinghouse s 100 kW SOFC cogeneration system... 

---