Application of Membrane Reactor and PEMFC-based Micro-CHP System in Off-grid Applications

The performance of an innovative m-CHP, rated at 5 kWel, is assessed at full and partial load. The system is powered by a polymer electrolyte membrane fuel cell (PEMFC), and hydrogen is produced via ethanol reforming in a membrane reactor. The membrane reactor selectivity may decrease with time and the separated hydrogen may contain other gases with penalties on cell voltage and system efficiency. To account for this aspect, the system is simulated at steady-state conditions by 1D phenomenological models of the membrane reactor and the fuel cells stack, for different hydrogen purities and load fraction. The fuel cell efficiency is affected by the presence, at anode side, of CO and inert gases coming from the membrane reactor and from the cathode side by membrane electrode assembly (MEA) cross-over, as well as by voltage decay over time. Then the innovative micro-combined heat and power (m-CHP) system, coupled with a heat pump, and heat and electricity storage systems, is applied to two off-grid houses, located in different climatic regions: it allows about 20% of fuel saving per year compared to a conventional m-CHP based on an internal combustion engine. The fuel saving reduces to 15% in case of low-purity hydrogen, and 10% in worst conditions with low-purity hydrogen and degraded cells.