Development of a novel solar reactor for thermochemical water-splitting

Hydrogen is an energy carrier with a great future potential. The field of application is huge because it has a high energy density and it is easy to handle. Furthermore the big advantage of emission-free combustion makes it unrivalled. A big challenge is the hydrogen production from renewable energy sources on an economic and industrial scale. The present work deals with the production of hydrogen by thermochemical water-splitting. The reacting material is a metal oxide that is oxidised by the water-splitting reaction with water and then thermally reduced at temperatures up to 1400°C. The redox-material remains solid during the whole cycle. The purpose of this work is to develop a novel solar reactor for the described process that supports temperatures of about 1400°C needed for the thermal reduction step. The major points of the novel design are to achieve high reacting surface areas for the chemical reaction and a high thermal efficiency of the reactor. Up to now a literature research of existing reactor concepts and the collection of requirements have been done. High reacting surface areas can be realised with a particle reactor, for example a fluidised bed. The high temperature needed for the thermal reduction can be achieved with a directly irradiated reactor concept without the use of a heat transfer fluid. An overview of possible reactor concepts has been outlined. In order to evaluate these concepts a system of criteria was created which helps to choose the most promising one. The next steps are to choose a suitable reactor concept and to develop a new experimental reactor based on this concept.