A Fuel Cell and Hydrogenation Engine Hybrid System Considering Efficiency Improvement for Partial-load Operation

Abstract

Cogeneration (CGS) using a solid polymer membrane-type fuel cell (PEM-FC) is hoped to become a next-generation distributed power supply. However, the short lifetime, high price, complex control, and decreased generation efficiency at partial load are issues that are still to be solved [52, 70]. Among these, the life and price of a fuel cell (FC) may improve greatly by advances in material development and recycling technology. Some examples report that the lowered generation efficiency at partial load operation is a resolvable issue, which can be seen from the results of a demonstration of PEM-FC for houses with a reformer [52, 70]. The causes of lowered efficiency at partial load operation can be separated into those concerning the reformer and those concerning the cell stack. A cell stack is divided into multiple stacks, and the method of controlling the number of operations according to the magnitude of the load has been examined in the past [25]. By this method, the load factor (the load added to the cell stack/capacity of the cell stack) of each cell stack rises. However, complications in the fuel cell system cause increasing energy unit costs. Thus, this chapter examines the hybrid PEM-FC and gas engine generator (NEG) system (HCGS). The operation of this system has the advantages of PEM-FC and NEG. Since the history of engine technology is long, NEG cogeneration is reliable and cheap compared with PEM-FC. However, the maximum generation efficiency and noise show low performance compared with PEM-FC.