Patent ID: 7739874

Claim:
A method of generating power via a gas turbine and a steam turbine in alternative exclusive modes which comprises: A. operating in a first mode by: a. supplying (i) coal bed methane, (ii) oxygen derived from an air separation plant with air supplied to the air separation plant being air from an air compressor of the gas turbine, and (iii) flue gas produced in the gas turbine wherein the flue gas is predominantly CO 2 , all under pressure, to a combustor of the gas turbine and combusting the coal bed methane to generate first heated combustion products and using the first heated combustion products and the flue gas to drive the gas turbine; b. supplying a hot flue gas stream produced in the gas turbine to a heat recovery steam generator and using the heat of the flue gas to generate steam by way of heat exchange with water supplied to the steam generator; c. supplying steam from the steam generator to a steam turbine and using the steam to drive the steam turbine; and d. compressing flue gas that passes through the heat recovery steam generator in a flue gas compression train and supplying (i) a part of the compressed flue gas stream to the combustor of the gas turbine and (ii) the remainder of the compressed flue gas stream to a suitable underground storage region; and B. operating in a second mode by: a. disconnecting the flue gas compression train and supplying coal bed methane and air from the air compressor of the gas turbine, both under pressure, to a combustor of the gas turbine and combusting the coal bed methane to generate second heated combustion products and a flue gas and using the second heated combustion products and the flue gas to drive the gas turbine; b. supplying a hot flue gas stream produced in the gas turbine to a heat recovery steam generator and using the heat of the flue gas to generate steam by way of heat exchange with water supplied to the steam generator; c. supplying steam from the steam generator to a steam turbine and using the steam to drive the steam turbine; wherein when power is not generated using the first mode, power is generated using the second mode and wherein when power is not generated using the second mode, power is generated using the first mode.