A Feasibility Study of a Japanese Power to Gas Concept—A Case Study of Rokkasho Village

Abstract

Power to Gas is a concept of producing hydrogen from intermittent renewable energies. In this study, the authors investigate the feasibility of a Japanese Power to Gas concept. The authors focus on Rokkasho Village in Aomori Prefecture, Japan. The area has affluent renewable energy potential and already has a lot of wind turbines and photovoltaic panels. It also has very cold winter weather and large amount of fossil fuels are used for room and water heating. In order to reduce such fossil fuel usage and CO2 emission in the area, the authors propose a fuel cell combined heat and power (CHP) system for cold area with local hydrogen supply chain, and analyze the feasibility of it. The energy and material balance, cost of hydrogen, and CO2 emission reduction effects are studied. From the electricity and fossil fuel consumption data of public facilities in Rokkasho Village, appropriate fuel cell CHP facilities are selected and hydrogen demand of them are calculated. Hydrogen supply is calculated from wind speed and sun light intensity data of the Rokkasho Village, renewable energy capacity, and threshold of electricity supply usable for hydrogen production on renewable energy output. Hydrogen storage capacities are determined to balance the supply and demand. The CAPEX is calculated based on the equipment in the CHP system and OPEX is calculated from electricity cost and industrial water price. The reduction of CO2 emission is calculated based on the amount of heat and electricity supply replaced with hydrogen CHP. The result indicates that 1. hydrogen production only from “excess” renewable energy is not economically feasible, 2. operation of electrolyzer can reduce the size of hydrogen production facilities and the cost of hydrogen, and 3. Hydrogen combined heat and power reduces more CO2 than just supplying heat from hydrogen.