Gas turbine with inlet air cooling system

An air driven gas turbine power system (1) including a gas turbine (2) having a compressor (3) with a compressor air inlet (4) and a compressed air outlet (5), and a downstream expansion turbine (6), coupled with a selectively operable compressor inlet air cooling system (10). The inlet air cooling system (10) includes a closed circuit volume of relatively high specific heat capacity working fluid, the circuit including a first warm working fluid mass storage region (11) and a second cooled working fluid mass storage region (12). Means (13) are provided to convey working fluid extracted from the first warm mass storage region (11) through a first air cooled heat exchanger region (14) whereby the working fluid is cooled by a source of cooler external ambient air and then conveyed into the second cooled mass storage region (12), and means (17) are provided to convey working fluid from the second cooled mass storage system through a second air cooling heat exchanger region (18) and then return to the first warm mass storage region. The cooling system (10) also includes means to convey ambient air via path (20) over the second air cooling heat exchanger region for cooling via the cooled working fluid therein prior to delivery to the gas turbine compressor air inlet.