Direct solar thermal splitting of water and on-site separation of the products. III. Improvement of reactor efficiency by steam entrainment

Hydrogen can be produced by direct solar thermal water splitting. Steam heated by concentrated solar radiation is partially dissociated. Hydrogen is separated from the hot mixture of water splitting products by gas diffusion through a porous ceramic membrane. The reactor thermodynamic efficiency in this process rises with increasing reaction temperature and with decreasing pressure at the downstream side of the gas-separating membrane. This paper discusses two attempts to raise the reactor efficiency, the first - by heat and mass recovery, using a steam injector in a two-stage reactor - and the other - by lowering reactor exit pressure of the hydrogen-enriched gas stream, using a multistage ejector. (C) 2000 International Association for Hydrogen Energy. Published by Elsevier Science Ltd. All rights reserved.