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Gold/Mining/Energy : SOFC vrs PEM Fuel Cells (Debate Forum) -- Ignore unavailable to you. Want to Upgrade?

To: Rickmas who wrote (76)	8/18/1999 9:37:00 PM
From: CH4	Respond to of 79

It's unfortunate that you were not able to post the complete Scientific American critique of P.E.M.technology instead of the misleading information that followed your intro. This tidbit illustrates some of the history of S.O.F.C. technology and was written before Global Thermoelectric's remarkable achievements. The link for the pictures are at the bottom of page Solid Oxide Fuel Cell (SOFC) Solid oxide fuel cell is a highly efficient and compact fuel cell in the next generation coming after the phosphoric acid fuel cell. OBJECTIVE Solid oxide fuel cell (SOFC) is expected to be commercialized as a compact cogeneration device which offers highly efficient energy conversion from natural gas to electricity. Tokyo Gas has been conducting fundamental research on cell component materials and developing manufacturing technologies with the aims of understanding the heart of SOFC as well as infallibly judging and estimating performance, potential applications, and economical feasibilities. Key technologies required for improvement of electricity generation efficiency and reliability in long-term operation are also being developed to expedite the commercialization. PRESENT STATUS In 1989, Tokyo Gas launched independent R&D programs for planar SOFC. In the early development stage, basic studies on cell component materials (i.e., electrodes and separators) were performed, and cells and stacks were manufactured based on the experiences learned from these studies. The size and electrical output of the cells and stacks increased in the course of development, which carved the milestones of successful manufacturing and testing of the world-largest single cells (Figure 1) in 1992 and producing the world-largest electrical output of 1.33 kW from the stack (Figure 2) in 1993. Presently, our efforts are focusing on technological innovations for improving the performance and reliability in long-term operation, for which many findings from fundamental researches are applied. Figure 1 The largest single-cell (23 cm sq., 97W) Figure 2 View of a 1kW-class stack PRINCIPLE Planar SOFCs have potential advantages over the other fuel cells. They can generate electricity more economically, more cleanly, and more efficiently with smaller sizes, and thereby can offer various applications including residential and industrial uses. As schematically illustrated in Figure 3(a), planar SOFCs are constructed basically by alternate piling of single-cells and separators, which is called a stack. The single-cell uses stabilized zirconia as the electrolyte which conducts oxide ions at around 1000øC. The air and fuel electrodes are fired on both surfaces of the electrolyte sheet (Figure 3(b)). In the air electrode, oxygen is electrochemically reduced to form oxide ions by accepting electrons from the external circuit. The oxide ions then move through the electrolyte and reach the fuel electrode. In the fuel electrode, the oxide ions electrochemically oxidize fuels and release electrons to the external circuit. Thus the electron flow is established from the fuelelectrode to the air electrode through the external load, which produces DC electricity. Also, a high operating temperature (around 1000øC) allows reforming of natural gas within the fuel cell (i.e., internal reforming). Not only hydrogen but also carbon monoxide, both of which are products of the internal reforming reaction, can react with oxide ions and be directly used as the fuel. The internal reforming eliminates a space-consuming and costly external reformer, so that compactness and reduced cost can be achieved. Figure 3 Schematics of the planar type SOFC APPLICATION The high energy conversion efficiency and simplified fuel processing system of the SOFC with an internal reforming system can make a compact SOFC system. A wide variety of applications can be expected ranging from large-scale power plants to super-compact cogeneration systems. The applications attractive to gas utilities include: large-scale cogeneration systems for distributed power generation plants (multi-MW class) small cogeneration systems for multi-family buildings (several tens of kW) super-compact cogeneration packages for residential uses (multi-kW class) PROSPECTS Most planar SOFCs ever fabricated and tested in the world are still fueled by hydrogen. In 1996, we are to be the first to manufacture and operate 1 kW class planar SOFC with the internal fuel reforming system which can use methane as a fuel. Following is the plan for the development of super-compact systems of multi-kilowatts which are thermally self-sustaining, and can generate both AC electricity and hot water using pipline natural gas as a fuel. These systems are expected to be commercialized in the beginning of the 21st century. For More Information: Masakazu Hishinuma Fundamental Technology Research Laboratory Tokyo Gas Co., Ltd. 16-25, Shibaura 1-Chome, Minato-ku, Tokyo 105, Japan Tel:+81-3-5484-4641 Fax:+81-3-3453-7583 E-mail:hisinuma@tokyo-gas.co.jp \| Menu \| Page top \| tokyo-gas.co.jp