Developments in the production of hydrogen by thermochemical water decomposition

Abstract

Recent developments in hydrogen production by thermochemical water decomposition are reported,<br />with an emphasis on hydrogen production from non-fossil energy sources such as nuclear and solar. Numerous<br />developments have been made on sulphur-iodine, copper-chlorine and other thermochemical<br />cycles. Efforts are described to lower the temperatures required in thermochemical cycles, so as to broaden<br />the range of potential heat supplies, including developments in the copper-chlorine thermochemical<br />cycle, which has significant potential due to its requirement for process heat at lower temperatures than<br />most other thermochemical processes. The thermodynamic evaluation of thermochemical water decomposition<br />processes is explained and illustrated by applying informative methodologies like exergy analysis,<br />which can assist in improving efficiencies and identifying limiting efficiencies. Thermochemical water<br />decomposition has several advantages relative to other hydrogen production processes that could make<br />it a competitive future option for hydrogen production, which is a key component of a hydrogen economy.<br />Recent developments, particularly using such non-fossil energy sources as nuclear and solar, suggest<br />that thermochemical hydrogen production could become commercial, and help meet the anticipated future<br />demand for hydrogen as an energy currency in the context of a hydrogen economy. Consequently, research<br />is likely to continue to improve thermochemical water decomposition processes.