Performance Evaluation of a Small Size Cogenerative System Based on a PEM Fuel Cell Stack

Abstract

The use of fuel cell systems for distributed generation represents an interesting option due to the intrinsic high efficiency and the potential to reduce the environmental impact of power supply in comparison with thermoelectric plants. In this paper the study of a cogenerative energy system based on a Proton Exchange Membrane fuel cell stack, that should satisfy a small electric utility, is reported; the capability of this cogenerative system to supply electrical and thermal power demand of a civil user has been investigated. In this research the electric efficiency has been calculated as net electric power on chemical power given to the system and the thermal efficiency as thermal power given to user on chemical power in input. Moreover, an energy saving index has been introduced to assess the cogenerative performance of this energy system. The investigation has been developed by experimenting an existing stack of fuel cell and studying its behaviour with a variable power demand. In particular, all the input and output mass flows have been evaluated to have parameters through which the operation of the whole cogenerative system, made by fuel cell stack and all the auxiliaries like compressor and pumps, could be simulated.