Gas and air turbine powerplant

The exhaust gas from a gas turbine (3) is fed to a first heat exchanger (5) to heat the air supply (41) from a compressor (9) supplying an air turbine (7). Further heat is extracted from the exhaust gas in a second heat exchanger (11) together with the exhaust gas from the air turbine to heat compressed air from a second compressor (13) supplying a second air turbine (15). The turbines drive a generator (17).