A solar thermochemical reactor for the reforming of natural gas to hydro­gen was designed, fabricated and operated in the scope of the European project SOLREF (Fig. 20.7). Based on the experience obtained in a previ­ous project (SOLASYS), in which the ‘proof-of-concept’ of solar steam reforming was demonstrated, an advanced reactor was developed in the SOLREF […]

The high temperature aerosol flow reactor (AFR) (Fig. 20.6) has been employed for the production of ceramics and for solar methane dissociation 20.6 (a) Schematic of aerosol flow reactor (Weimer et al., 2001); (b) installed solar thermal aerosol reactor (Dahl et al., 2004). (Perkins et al., 2008). ‘Proof-of concept’ experiments were carried out for the […]

Another type of rotating reactor (Fig. 20.5) is the CR5 developed at the Sandia National Laboratories (Diver et al., 2008). The reactor is a receiver/ reactor/recuperator that consists of counter rotating rings or disks. Robo – cast redox material in the form of fin segments is adjusted on the rotating disks. With the aid of […]

A ‘rotary’ type system (Fig. 20.4) that was designed for two-step thermo­chemical water-splitting cycles, had separate dual cells for the water­splitting and the regeneration. It was developed at the Tokyo Institute of Technology (Kodama and Gokon, 2007; Kaneko et al., 2007) and consists of ceramic foams coated with the redox material and adapted on a […]

Cavity solar reactors (Fig. 20.3) were introduced in the work of Trombe et al. (1973), for melting of oxides, Flamant et al. (1980) for calcite decom­position, and Steinfeld et al. (1998b) and Haueter et al. (1999) for oxide reduction. As the name suggests, concentrated radiation enters a cavity aperture via a window. In Steinfeld et […]

For catalyzed reactions, reactors based on packed beds of porous solid cata­lyst particles are a standard approach in the chemical industry. Adaptation to solar operation via assembly of multiple tubes to form a receiver is an obvious approach. Stein et al. (2009) have followed this route for solar steam reforming, for example. Recently a thermal […]

The design of solar thermochemical reactors has been an issue of research over the last three decades. Some of the most significant reactor designs are presented in the following paragraphs.

Direct thermal water-splitting (Eq. [20.11]) is a reaction that requires very high temperatures (>2000°C). 2H2O + Energy ^ 2H2 + O2 [20.11] The reduction of the temperature of the water-splitting reaction can be achieved via thermochemical cycles based on redox pairs. One of the earliest investigations for multi-step hydrogen production from water-splitting was by Funk […]