Patent ID: 7614237

Claim:
A method of operating a Compressed Air Energy Storage (CAES) system, the system including an air storage for storing compressed air, an auxiliary compressor for supplying compressed air to the air storage, a power generating structure, a heat exchanger constructed and arranged to receive heat from the power generating structure and to receive compressed air from the air storage, at least one auxiliary combustor constructed and arranged to receive compressed air from the air storage, an air expander constructed and arranged to be fed with heated air from one of the heat exchanger or the at least one auxiliary combustor and to expand the heated air, and an electric generator, associated with the expander, for producing electric power, the method including selectively operating the system in one of the following power production modes of operation: a) a main power production mode by: ensuring that the at least one auxiliary combustor is inoperable and the power generating structure is operable, providing heat from the power generating structure to the heat exchanger and providing compressed air from the air storage to the heat exchanger so that the compressed air received from the air storage is heated in the heat exchanger, with the heat exchanger feeding the heated compressed air to the air expander, expanding the heated compressed air in the expander, and providing the electric power via the generator in addition to power produced by the power generating structure, or b) a synchronous reserve power mode by: ensuring that the at least one auxiliary combustor is operable and the power generating structure is inoperable, withdrawing compressed air from the air storage, preheating the withdrawn compressed air in the at least one auxiliary combustor that feeds the air expander, expanding heated air received from the at least one combustor in the air expander, and providing substantially immediate start-up power via the generator.