We propose a novel concept for power generation that involves the combination of a low-condition heat generator (LCHG), such as a light water nuclear reactor or a biomass combustion boiler, with an advanced closed-cycle oxy-fuel combustion gas turbine—a type of complex and efficient oxyfuel gas turbine plant, in accordance with our previous studies in combination with a simple oxy-fuel gas turbine plant. In this study, a LCHG is designed to heat water to saturated steam of a few MPa, to assist in the generation of the main working fluids, instead of a compressor used in the advanced oxy-fuel gas turbine. This saturated steam can have a lower pressure and temperature than those of an existing nuclear power plant or biomass-fired power plant. We estimated plant performances from a heat balance model based on a conceptual design of a plant for different gas turbine inlet pressures of 2.5–6.5 MPa and temperatures of 1300 and 1500°C, taking into account the work to produce O2 and capture CO2. While the net power generating efficiencies of a reference advanced oxy-fuel gas turbine plant are estimated to be about 52.0% and 56.0% at 1300 and 1500°C, respectively, and conventional steam power generation is assumed to have an efficiency of about 35% or less for pressures of 2.5–6.5 MPa, the proposed hybrid plant achieved 42.8–44.7% at 1300°C and 47.8–49.2% for 1500°C. In the proposed plant, the power output contributed by a LCHG may be obtained by subtracting the LNG contribution from the whole net power output. Even supposing that the generation efficiency of the LNG system in the proposed plant remains equal to that of the reference plant (56.0% at 1500°C), some components used in the reference plant are omitted by installation of the LCHG. The efficiency of LCHG system can be estimated 37.4% for 6.5 MPa and 33.2% for 2.5 MPa, even though the LHCG system may be regarded as consisting of fewer plant facilities than a conventional LCHG power plant.

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