Solar thermochemical production of hydrogen—A review

This chapter reviews the underlying science and describes the technological advances in the field of solar thermochemical cycles and processes for producing hydrogen that use concentrated solar radiation as the energy source of high-temperature process heat. 12.1 Thermodynamics of Solar Thermochemical Processes A comprehensive thermodynamic analysis of solar thermochemical processes is described by Fletcher (2001) and by Steinfeld and Palumbo (2001). The principal concepts are sum-marized herein. Solar thermochemical processes are based on the use of concentrated solar radiation as the energy source of high-temperature process heat for driving an endo-thermic chemical transformation. Three main optical configurations based on parabolic-shaped reflectors are at present commercially available for large-scale concentration of solar energy: the trough system, the tower system, and the dish system. These three systems are schematically shown in Figure 12.1. Trough systems use linear, 2D, parabolic mirrors to focus sunlight onto a solar tubula