High-temperature solar chemistry for converting solar heat to chemical fuels

This paper reviews the recent developments on thermochemical conversion of concentrated solar high temperature beat to chemical fuels. The conversion has the advantage of producing long term storable energy carriers from solar energy. This conversion also enables solar energy transportation from the sunbelt to remote population centers. The thermochemical pathway is characterized by a theoretical high efficiency. However, there are solar peculiarities in comparison to conventional thermochemical processes-high thermal flux density and frequent thermal transients because of the fluctuating insolation-, and conventional industrial thermochemical processes are generally not suitable for solar driven processes. Therefore, the adaptation to such peculiarities of solar thermochemical processes has been the important R&D task in this research field. Thermochemical water splitting, steam or CO2 gasification of coal, steam or CO2 reforming of methane, and hydrogenetive coupling of methane, are industrially important, endothermic processes to produce useful chemical fuels such as hydrogen, synthesis gas and C-2-hydrocarbons, which have been examined as solar thermochemical processes. The technical. developments and feasibilities to conduct these endothermic processes by utilizing concentrated solar radiation as the process heat are discussed here. My recent experimental results to improve the advanced solar thermochemical technologies are also given. (C) 2003 Elsevier Ltd. All rights reserved.