A review on borehole seasonal solar thermal energy storage

Because of the intermittence and unreliability of solar radiation, a seasonal thermal energy storage system is needed to maximize the potential utilization of solar energy. Borehole seasonal solar thermal energy storage is one of the most common energy storage methods and some applications have been conducted. This paper reviews the studies on borehole seasonal solar thermal energy storage. Analytical and numerical models of underground regenerator and system simulations are summarized here. Large application projects used for center solar heating in European counties and some small scale experimental studies are included. Problems and barriers of the development of borehole heat storage in China are also given. (C) 2015 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).