Use of High Temperature Process Heat for Solar Materials Conversion

Water is a raw material in all important processes for hydrogen production. It is used together with carbonaceous material like natural gas in reforming process and it is used as the only raw material in water electrolysis and in thermo-chemical cycle. Hydrogen as an energy carrier is only sustainable if it helps reducing CO2 emissions and if it is generated by applying renewable resources. The paper gives an overview on how concentrating solar technologies can be applied to reduce greenhouse gas emissions compared to conventional processes like steam reforming of methane or to totally avoid such emissions by using solar generated heat to power thermochemical cycles for water splitting. The probable first step to do this would be the integration of established technologies like SMR with solar energy. Secondly one has to proceed successively to renewable carbon free hydrogen production. The application of a solar driven reforming process is already at the edge to be competitive and has the potential to open the gate to the hydrogen economy. Thermo-chemical cycles for hydrogen production exclusively from water represent the long-term option