Evaluation of natural gas combined cycle power plant for post-combustion CO2 capture integration

Over the coming decade, gas-fired power plants are projected to account for a substantial share of global output. CO2 capture would be required to mitigate the associated emissions. Thus, high fidelity models of a 440 MW natural gas combined cycle power plant, a CO2 capture plant and a CO2 compression train were built and integrated for 90% capture level. Power output is observed to fall by 15%, while cooling water demand increases by 33%. A 40% exhaust gas recirculation (EGR) causes a 10 MW power recovery, but increases cooling water demand further. It is shown that higher exhaust gas CO2 concentration enhances mass transfer in the capture plant, which reduces its steam requirement. Supplementary firing (SF) of the exhaust gas is observed to generally improve the plant output. Economic analysis, performed via a bottom-up approach, reveals integrated plant overnight cost to be 58% higher than the power plant cost, discouraging deployment of CO2 capture. The impact of EGR is marginal, while SF implementation almost doubles the overnight cost. Cost of electricity increases by 30% for the integrated plant, but only by 26% with EGR, and 24% with SF. However, the price of gas remains the largest contributor to cost of electricity.