100-Wh multi-purpose particle reactor for thermochemical heat storage in concentrating solar power plants.

Dispatchable power generation on demand is a key issue for commercial deployment of Concentrated Solar Power (CSP) plants. The intermittence of the solar resource would be overcome by integrating an energy storage system. Compared to sensible or latent heat storage, thermochemical storage presents the advantage of having higher energy density, being capable to store energy as long as desired at ambient temperature and the option of transporting the storing material to generate heat at the end-use location. One route for thermochemical storage is based on metal oxides redox reactions. Here, thermal energy is stored in chemical form during the endothermic reduction and it is released during the exothermal oxidation, generally at a different temperature level. Some chemical reactions proceed at temperatures high enough to operate heat engines at high efficiency, as in electricity generation. In addition, heat is recovered at essentially isothermal conditions, which gives advantage to process controllability. This work presents a particle-based reactor designed to analyze thermochemical storage using redox reaction processes in the temperature range from ambient to 1100 degrees C and different pressures over the atmospheric. Depending on gas flow rate, different particle regimes from fixed-bed to fluidized bed can be analyzed. It is planned to incorporate the reactor in a test bench, which creates the environment to simulate real CSP plant working conditions. The test bench will be provided with gas analysis equipment, temperature and pressure sensors, gas flow controllers, etc. to acquire as much information as possible from the system without disturbing it. The overall test bed will allow evaluating different parameters as reaction yield, particle size, and successive oxidation / reduction cycles on the process cyclability, the mechanical strength and abrasion resistance of storing materials under different temperature and pressure working conditions. (C) 2013 M. Romero. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/).