Solar-aided precombustion CO2 capture in natural gas combined cycles

The integration of solar energy in natural gas combined cycles has recently received much attention in the global efforts to reduce CO2 emissions. Optimum integration options have been proposed in the literature which enhance the conversion of solar thermal energy into electricity compared to solar-only power plants. The so-called “Integrated Solar Combined Cycles” (ISCCs) may embed the solar heat input in the bottoming steam cycle as well as in the topping gas turbine. Another route for the efficient abatement of CO2 in natural gas combined cycles consists in the integration of hydrogen/syngas production technologies such as reforming and water-gas shift reactions. The heat required for the endothermic steam reforming reaction can be provided by burning part of the hydrogen-rich syngas or alternatively by the partial oxidation of methane and oxygen within an autothermal reformer. After CO2 removal the resulting syngas mostly containing hydrogen is burned in the gas turbine to produce electricity or may be further processed to high-purity hydrogen. In this work the integration of solar energy in natural gas combined cycles with precombustion CO2 capture is evaluated. These plants include additional high temperature heat sinks compared to a plant without CO2 capture that could be conveniently fed by solar thermal energy. Different layouts are proposed and analyzed in the search for the optimum integration. The achievable solar share and thermodynamic and environmental performance is compared against those achievable in ISCCs without CO2 capture.