Residential cogeneration system

Onovwiona H.I. Ugursal V.I. Residential Cogeneration Systems Review of the Current Technology , Renewable Sustainable Energy Reviews, 2006, 389-431... 

RESIDENTIAL COGENERATION SYSTEMS BASED ON PEM FUEL CELLS... 

Tabata, T., O. Yamazaki, H. Shintaku et al. 2009. Degradation factors of polymer electrolyte fuel cells in residential cogeneration systems. In Polymer Electrolyte Fuel Cell Durability, eds. F.N. Buchi, M. Inaba, and T.J. Schmidt, pp. 447-463. New York, NY Springer. 

Degradation Factors of Polymer Electrolyte Fuel Cells in Residential Cogeneration Systems... 

The basic construction and materials of a PEFC stack for residential use are not so different from those for automobile use and so the durability issues are basically the same as those for automobiles. However, quite long life (40,000-90,000h), which cannot be easily verified by actual operation, is required for residential use for economic reasons, which means the durability issue is difficult solve. Although the operation conditions of PEFCs in residential cogeneration systems are generally milder than those in automobile applications, some of them are specifically severe and important for residential use. A comparison of the operation conditions and their influence on the durability of cell stacks for residential and automobile use is summarized in Table 2. 

In this chapter, centered on such specific factors for residential application, degradation phenomena observed in long-term operation experiments assuming residential cogeneration systems at Osaka Gas are reviewed and analyzed. In addition, the present status and the potential of the durability of PEFCs for residential use are briefly reported. 

The overall residential fuel cell micro cogeneration system can be seen in Figure 1. The fuel processing is one of the sections of this whole system. 

V. Dorer, R. Weber, A. Weber, Performance assessment of fuel cell micro-cogeneration systems for residential buildings. Energy and Buildings 37 (2005) 1132-1146. 

Echigo, M., Shinke, N., Takami, S., Higashiguchi, S., Hirai, K., and Tabata, T. Development of residential PEFC cogeneration systems Ru catalyst for CO preferential oxidation in reformed gas. Catalysis Today, 2003, 84, 209. 

A small fuel cell of about 1-kW in capacity, could cogenerate year-round to provide base-load power and hot water. Larger fuel cells would provide too much heat than a home can use most of the time. The DOE estimates that the optimal size for a residential combined heat and power (CHP) or cogeneration system in the United States is about 0.75-kW for a PEM fuel cell. 

Ebara Ballard (2004). IkW Cogeneration System Using Kerosene Fuel for the Japanese Residential Market Completed the Prototype Unit and Started Its Verification Test. Ebara Ballard Corporation, Ebara Corporation, Nippon Oil. Japan. Available at http //www.ebara.co.jp. 

Where the intended range of applications does not allow for a platform architecture at the meta-system level, the platform products then need to be defined at the system level. In fact, the concept of a platform-based architecture can be pursued at the component as well as the system level. Ballard, for example, defines its platforms at the stack level. It is currently advertizing five stack platforms. Each stack platform has a different voltage range, reactant pressure (air and fuel), and cell aspect ratio, optimized for the intended application, whether it be for backup (telecommrmications), motive power (forklift trucks), transportation (buses), or residential cogeneration. 

For small power-unit systems such as the SOFC cogeneration systems for the residential applications, usually no purge gas will be used. Thus, there arises a big possibility that the anodes can be reoxidized during the start-up and shutdown cycles. 

In Japan, a demonstration program for the SOFC cogeneration systems for residential houses has been initiated for the period 2007-2010. Kyocera reported the statistics of troubles during the demonstration program [61, 62] this is summarized in Fig. 18.7. Troubles in systems were well treated to be improved so that a number of troubles decrease year by year. 

Table 1 Required specification of residential polymer electrolyte fuel cell cogeneration systems...

CO tolerance is still an issue for residential PEFC cogeneration systems in which hydrogen-rich gas reformed from city gas or oil is utilized as a fuel for the PEFC. Although the allowable CO concentration for a Pt-Ru anode catalyst, as low as 10 ppm, is stably achieved by a recent fuel processing system (Echigo et al. 2006) and so CO tolerance is not an apparent problem for achievement of the required performance, there are quite a few reports on the long-term durability of CO tolerance. Furthermore, it has not been clarified how the addition of breed air to the fuel which is widely applied for a reformed-gas-fueled PEFC influences the long-term durability of the anode and the membrane. 

An example of the resnlt of the dnrability test of a PEFC cell stack in an actual cogeneration system for residential use is shown in Fig. 13. No degradation tendency... 

Major degradation factors of the ME A for residential PEFC cogeneration systems were reviewed on the basis of the results of long-term operation data, and are summarized as follows. 

Fig. 1 Residential polymer electrolyte fuel cell cogeneration system operated in a customer s house...

They built the 1-kW SOFC cogeneration system for residential houses and tested one system in an actual house together with Osaka Gas in 2005 [11]. The start-up time is typically 2 h. A typical result of 24 h operation is shown in Fig. 2.11. During the night, electricity demand is essentially zero except for the refrigerator. Power demand during daytime fluctuates between 500 and... 

W. The SOFC system supplies 1 kW, and the rest of the power demand is supplied from grid electricity. The characteristic load-following feature of the cogeneration system is shown in Fig. 2.11. These tests confirm that the system efficiency for a residential house is 43%-48% LHV as an average value for the 24-h test period. 

Figure 1.18 Three generations of Ballard Mark 1030 (1320 W rated power) technology. The Mark 1030 V3 (on left) is 40% lighter and 26% smaller than the previous generation of residential cogeneration fuel cell. (Image courtesy of Ballard Power Systems, Inc.)...

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