Three schemes of the gas turbine cycle have been analyzed from the point of view of the second law thermodynamics: the conventional gas turbine cycle, where natural gas (methane), is oxidized by air; a closed gas turbine cycle, in which methane is oxidized by oxygen; and a proposed gas turbine cycle, in which the methane is first converted to synthesis gas (a mixture of carbon, oxide and hydrogen), than,pari of the synthesis gas is oxidized by oxygen for electric energy generation while the rest is withdrawn from, the power cycle for production of methanol, ether, synthetic fuel, etc. It has been shown that the third integrated scheme of natural gas, usage provides minimum entropy increase as well as suppression of toxic nitrogen oxides generation in combustion: products. Therefore, it could be c prospective energy-saving technology.