Design of a hybrid renewable energy system based on supercritical water gasification of biomass for off-grid power supply in Fukushima

This paper proposes an innovative hydrogen-based hybrid renewable energy system (HRES), which can be used to provide electricity, heat, hydrogen, and water to the small community in remote areas. The HRES introduced in this study is based on the integration of solar power generation, hydrogen generation from supercritical water gasification (SCWG) of wet biomass feedstock, hydrogen generation from solar water electrolysis, and a fuel cell to convert hydrogen to electricity and heat. The wet biomass feedstock contains aqueous sludge, kitchen waste, and organic wastewater. A simulation model is designed and used to investigate the control strategy for the hydrogen and electricity management through detailed size estimation of the system to meet the load requirements of a selected household area, including ten detached houses in a subject district around the Shinchi station located in Shinchi-machi, Fukushima prefecture, Japan. As indicated by results, the proposed HRES can generate about 47.3 MWh of electricity and about 2.6 ton of hydrogen per annum, using the annual wet biomass consumption of 98 tons, with a Levelized Cost of Energy (electricity and heat) of the system at 0.38 $/kWh. The implementation of the proposed HRES in the selected residential area has GHG emissions reduction potential of about 21 tons of CO_2-eq per year.