A power generation system may include a gas turbine system including a turbine component, an integral compressor and a combustor to which air from the integral compressor and fuel are supplied. The combustor is arranged to supply hot combustion gases to the turbine component, and the integral compressor has a flow capacity greater than an intake capacity of the combustor and/or the turbine component, creating an excess air flow. A turbo-expander powers a generator. A first control valve controls flow of the excess air flow along an excess air flow path to the turbo-expander. An eductor may be positioned in the excess air flow path for using the excess air flow as a motive force to augment the excess air flow with additional air.