Toward economically rational hydrogen production from solar energy: From battery versus hydrogen to battery x hydrogen

Abstract

The use of renewable energy as a main primary energy source can be perceived as a common target of all the countries in the world to reach a sustainable society late in this century. Toward the sustainable goal, the photovoltaic and wind power generations are expected to play important roles in coming decades. To counter the intermittency of their power outputs, economically feasible energy storage measures are necessary. In this chapter, the storage technologies as key technologies for making intermittent renewable energies a main power generation option are discussed focusing on the battery and hydrogen energy systems. The rationality of hydrogen energy as a long-term storage measure is first discussed by a Fermi estimate formula proposed by Hasegawa. Then the rationality of integrating battery with hydrogen production from solar energy is discussed. A concrete example of the integrated system optimization is introduced to clearly show that the integration will lead to the realization of an economically viable hydrogen production from solar energy.