Natural gas combined cycle power plants with CO2 capture - Opportunities to reduce cost

A detailed analysis covering a thermodynamic and economic evaluation of a 440 MWe natural gas combined cycle power plant with an integrated CO2 removal plant, using an aqueous solution of monoethanolamine (MEA) has been used as basis for this study. The flow sheet representing the CO2 capture plant is optimized with respect to operation parameters and includes absorber intercooling and lean vapor recompression. In addition, to further reduce the costs of CO2 capture, the gas turbine utilizes exhaust gas recirculation (EGR) with a level of 40%, and thereby the CO2 content in the gas turbine exhaust gas is increased to almost double that of conventional operating gas turbines. A techno-economic evaluation of the simulated results of the extended MEA absorption/desorption process integrated into the natural gas combined cycle (NGCC) with EGR and CO2 compression is performed. The sensitivity of the economical model's response to changes in different economical input conditions has also been evaluated. It is shown that EGR in combination with a reduced specific reboiler duty adds significant benefits to both the operational and capital expenditures. It is also shown that the fuel costs and currency rates play important roles in providing reliable cost estimations.