Optimization of carbon-capture-enabled coal-gas-solar power generation

Computational optimization is used to determine the optimal design and time-varying operations of a carbon dioxide capture retrofit to a coal-fired power plant. The retrofit consists of an amine-based temperature-swing absorption system, to which process steam is supplied from an auxiliary unit. Two candidate auxiliary heat sources are explored: natural gas and solar thermal. The NPV (net present value) of the retrofitted facility is maximized to determine which auxiliary system is preferable, under a variety of economic conditions. Optimized NPV is found to be most sensitive to the price of natural gas and the electricity price. At an 8% real discount rate, without renewable energy incentives, natural gas prices must be high (in excess of 10 USD/GJ) for a solar thermal design to be preferable, and electricity prices must reach ≈55 USD/MWh in order for solar-thermal-based designs to have a positive NPV. Incentives such as investment tax credits and solar power purchase agreements can make solar-thermal-based designs preferable to natural-gas-based designs under certain circumstances.