Abstract
Switching from fossil fuels to renewable energy will require efficient and reliable forms of energy storage. One promising chemical storage pathway is to use renewable energy to generate hydrogen, which then can later be combusted or converted to water and electricity in a fuel cell to recover the stored energy. In this issue we discuss the critical role hydrogen will play in our energy future. We also present solar thermochemical hydrogen (STCH) processes as alternatives to generating it via direct water electrolysis. Finally, we present the opportunities and challenges facing solar energy in general, and photovoltaics in particular. With continued progress in photovoltaics and increasingly more efficient ways of generating hydrogen, solar energy should enable the hydrogen economy.