Patent ID: 6848259

Claim:
A compressed air energy storage system, comprising: a cavern for storing compressed air, a power train comprising a rotor and one or several expansion turbines, and a system providing the power train with the compressed air from the cavern that includes a recuperator for preheating the compressed air and a first valve arrangement, that controls the flow of preheated air from the recuperator to the power train, and the compressed air energy storage system further comprising a system for warm-keeping of the power train during stand-by operation of the compressed air energy storage system wherein the system for warm-keeping includes the recuperator and/or an auxiliary electrical air heater, an airflow being directed to the warm-keeping system for preheating and the thus preheated airflow being directed away from the system for warm-keeping and to the power train, and the system for warm-keeping furthermore includes an additional, second valve arrangement that controls either said airflow to the system for warm-keeping or said airflow away from said system for warm-keeping and to the power train, wherein the auxiliary electrical air heater and the second valve arrangement are positioned such that they bypass the first valve arrangement that controls the admission of compressed air to the power train.