Thermochemical seasonal energy storage for solar thermal power

Abstract

During the many years that thermochemical energy storage has been under investigation, the concept has been plagued with two persistent problems: high capital cost and poor efficiency. Literally hundreds of chemical reactions have also been carried out. For short-term storage, thermochemical systems suffer in comparison with highly efficient sensible storage media such as molten salts. Long-term storage, on the other hand, is not cost-competitive with systems employing fossil backup power. Thermochemical storage will play a significant role in solar thermal electric conversion only under highly select circumstances. The portion of electric demand served by solar plants must be sufficiently high that the balance of the grid cannot fully supplant seasonal storage. High fossil fuel costs must preclude the use of gas turbines for backup power. Significant breakthroughs in the development of one or more chemical reaction systems must occur. Ingeniously integrated systems must be employed to enhance the efficiency and cost-effectiveness of thermochemical storage. A promising integration scheme discussed herein consists of using sensible storage for diurnal cycling in parallel with thermochemical seasonal storage. Under the most favorable circumstances, thermochemical storage can be expected to play a small but perhaps vital role in supplying baseload energy from solar thermal electric more » conversion plants. « less