Control of a large scale solar thermal energy storage system

Dynamic simulation results for a thermal energy storage (TES) unit used in a parabolic trough concentrated solar power (CSP) system are presented. A two-tank-direct method is used for the thermal energy storage. The heat transfer fluid flow rate through the solar collector maintains a constant outlet temperature and the flow rate through the boiler regulates power output. The use of storage greatly improves the system´s ability to provide power at a constant rate despite significant disturbances in the amount of solar radiation available. It can also shift times of power generation to better match times of consumer demand. By contrast, a CSP system without storage undergoes large fluctuations in power output, particularly during intermittent cloud cover. Adding a storage system increases the solar share of the power plant by over 80%, reducing the requirement for supplementary fossil energy by as much as 8.4 MWh daily.