Thermal energy storage system for energy conservation and water desalination in power plants

This paper presents a novel application of a sensible TES (thermal energy storage) system for simultaneous energy conservation and water desalination in power plants. First, the TES mitigates negative effects of high ambient temperatures on the performance of ACC (air-cooled condenser) that cools a 500 MW CCPP (combined cycle power plant); next, the same TES satisfies the cooling requirements in a 0.25 mgd (950 m3/d) MED (multi-effect evaporation desalination) plant. Stack gases from CCPP are used to drive an ARS (absorption refrigeration system) which maintains the chilled water temperature in a TES tank. A process model integrating CCPP, ARS, TES, and MED has been developed to optimize the volume of the TES. Preliminary analysis showed that a tank volume of 2950 m3 was adequate in meeting the cooling requirements of ACC and MED in both hot and cold seasons. The proposed TES has a potential to save 2.5% of the power loss in a CCPP on a hot summer day. Further, a desalination capacity of 0.25-0.43 mgd (950-1600 m3/d) can be achieved with top brine temperatures between 100 °C and 70 °C of MED.