This chapter consists of three sections, ‘Dynamic Characteristics of PEFC / Woody Biomass Engine Hybrid Microgrid’, ‘Exergy Analysis of the Woody Biomass Stirling Engine and PEFC Combined System with Exhaust Heat Reforming’ and ‘Exergy Analysis of A Regional Distributed PEM Fuel Cell System’. The chapter describes the exhaust heat of the combustion of woody biomass engine using a Stirling cycle that was used for the city gas reforming reaction of a PEFC system. The response characteristic of PEFC and woody biomass engine is investigated by the experiment and numerical analysis. Finally, a combined system that uses the exhaust heat of the woody biomass Stirling engine for the steam reforming of city gas and that supplies the produced reformed gas to a PEFC is proposed.