Energy, Vol.58, 36-44, 2013
Low CO2-emissions hybrid solar combined-cycle power system with methane membrane reforming
Based on the principle of cascade utilization of multiple energy resources, a gas-steam combined cycle power system integrated with solar thermo-chemical fuel conversion and CO2 capture has been proposed and analyzed. The collected solar heat at 550 degrees C drives the endothermic methane reforming and is converted to the produced syngas chemical exergy, and then released as high-temperature thermal energy via combustion for power generation, achieving its high-efficiency heat-power conversion. The reforming reaction is integrated with a hydrogen separation membrane, which continuously withdraws hydrogen from the reaction zone and enables nearly full methane conversion. The CO2 enriched gas being concentrated in the retentate zone is collected and processed with pre-combustion decarbonization. The system is thermodynamically simulated using the ASPEN PLUS code. The results show that with 91% CO2 captured, the specific CO2 emission is 25 g/kWh. An exergy efficiency of 58% and thermal efficiency of 51.6% can be obtained. A fossil fuel saving ratio of 31.2% is achievable with a solar thermal share of 28.2%, and the net solar-to-electricity efficiency based on the gross solar heat incident on the collector is about 36.4% compared with the same gas-steam combined cycle system with an equal CO2 removal ratio obtained by post-combustion decarbonization. (C) 2013 Elsevier Ltd. All rights reserved.
Keywords:Hybrid power system;Solar thermal energy;Membrane reformer;Thermo-chemical conversion;CO2 capture