A Small-scale Fuel Cell Cogeneration System Considering Partial Load and Load Fluctuation

Abstract

The solid high-polymer-film-type fuel cell (PEM-FC) system is used as the power supply equipment for transportation and replaces an internal combustion engine. A reduction of the environmental load is expected through the cogeneration system’s (CGS) use of the PEM-FC system as a distributed power supply to individual houses, apartments, and so forth [1–3]. The growing use of distributed power systems, such as fuel cells, the reduction of power-transmission losses, and an increase of waste heat recovery are expected. Therefore, the reduction of carbondioxide emission is also expected as compared to conventional energy supply methods using commercial electric power. At present, a decisive method of hydrogen supply and storage in houses is not proposed. Fuel cell CGS of the reforming type which obtains hydrogen from natural gas and methanol is promising. In order to provide high efficiency and to perform a catalyst reaction by methanol steam reforming, it is necessary to manage the heat quantity [4–7]. Furthermore, if approximately 3% carbon monoxide is contained in the gas after the steam reforming reaction and is supplied to a fuel cell, poisoning of the electrode catalyst will occur, and power generation will be difficult. Thus, after preparing the shift unit and CO oxidation unit in the process after the reforming reaction, the CO concentration is approximately 10 ppm. Since the shift reaction, CO oxidation reactions, and the reforming reaction are performed using a catalyst, each reaction system is controlled in a suitable temperature range.