Abstract: A gas turbine power plant operating on a dual Brayton cycle and utilizing a circulating pressurized fluidized bed combustor is disclosed. An open Brayton cycle is provided in which the hot flue gas from the fluidized bed combustor is expanded to extract work to drive compressors to supply combustion air for the fluidized bed combustor and to drive an electric generator to produce electricity. The residual heat of the flue gas exhausted from the open Brayton cycle can be utilized for heat cogeneration at high power-to-heat ratios. A closed Brayton cycle is also provided, the working medium of which is heated in an indirect heater of the circulating pressurized fluidized bed combustor and expanded to extract work to drive another electric generator. The air supplied by the open Brayton cycle is also used to fluidize the heated particles in the indirect heater.