Receiver/Reactor Concepts for Thermochemical Transport of Solar Energy

Thermochemical transport of solar energy based on reversible chemical reactions may be a way to take advantage of the high-temperature capabilities of parabolic dishes, while minimizing pipe network heat loss, since energy is transported at ambient temperatures in chemical form. Receiver/Reactor design is a key to making thermochemical transport a reality. In this paper the important parameters for solar receiver and chemical reactor design and how they relate to each other are presented. Three basic receiver/reactor types, applicable to thermochemical receiver design, are identified: (1) Tube Receiver/Reactors have tubular reactor elements which are directly heated by solar energy in the receiver. (2) Indirect Receiver/Reactors use an intermediate heat transfer fluid between the receiver and reactor. (3) Direct Absorption Receiver/Reactors absorb sunlight directly on the reactor catalyst. Advantages, limitations, and risks associated with each design are discussed and examples of those that have been built are given. Each type offers its own set of advantages and risks, and warrant further investigation.