Nihon Kikai Gakkai ronbunshu (Jan 2022)
Evaluation of regional storage characteristics and external energy input of photovoltaic-derived hydrogen in an air heat exchanged hydrogen storage alloy system
Abstract
In recent years, hydrogen has been attracting attention as a long-term energy storage that can absorb fluctuations of the output of variable renewable energy sources. While there are several hydrogen storage methods, hydrogen storage alloy is one of the most suitable methods for stationary hydrogen storage. Since hydrogen storage alloy’s characteristics of absorption and desorption heavily depends on operating temperature, temperature control is one of the critical issues in the design of the hydrogen storage alloy system. As a new method for controlling alloy’s temperature, the authors have developed the air heat exchanged hydrogen storage alloy system that is supplying an air temperature for hydrogen storage alloy. In this study, the year-round hydrogen balance and the heat input required for temperature control of this air heat exchanged hydrogen storage alloy system are simulated for an independent electric power utilization system using photovoltaic power generation with hydrogen energy storage system assuming arbitrary regions and electric power demand patterns in Japan. Based on the simulation results, the external heat input of the system was systematically evaluated, and the energy-saving performance of the alloy temperature control of the storage alloy system in each region and the feasibility of seasonal energy shift by the hydrogen storage system were evaluated. The results show that the air heat exchanged hydrogen storage alloy system is a highly energy-efficient system that can adjust the temperature using less energy than the heat of alloy chemical reaction heat regardless of the regional variation of temperature or type of electric demand pattern, although the amount of energy input varies depending on the region.
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