Techno-Economic Analysis of the Solid Oxide Semi-Closed CO2 Cycle and Comparison with Other Power Generation Cycles with CO2 Capture

Abstract This work presents the techno-economic analysis of the Solid oxide semi-closed CO2 cycle (SOS-CO2), a hybrid semiclosed cycle with solid oxide fuel cells (SOFC) recently developed by Politecnico di Milano for power generation from natural gas with near-zero CO2 emissions. The cycle is able to achieve an outstanding net electric efficiency of 75.7%, capturing more than 99% of the generated CO2. All the cycles components have been designed and sized with the aim of assessing performance and capital cost. Performance and economic key performance indicators are compared with those of two benchmark technologies for power generation with CO2 capture: the Allam cycle and a combined cycle equipped with ammines for post-combustion capture. Moreover, a sensitivity analysis is performed on the forecasted cost of natural gas and SOFC stacks. The results indicate that the specific total capital requirement of the SOS-CO2 cycle (2.52k€/kWel) is considerably higher than the Allam cycle (1.93 k€/kWel) and combined cycle with post-combustion capture (1.98 k€/kWel). On the other hand, the SOS-CO2 cycle benefits from its far higher efficiency (73.3% vs. 53.9% of the Allam cycle and 52.8% of the combined cycle) which makes the cycle less sensitive to the fuel cost and CO2 tax. In terms of cost of electricity, the SOS-CO2 cycle results the best technology for natural gas prices above 8 €/GJ, while the Allam cycle appears to be the preferred option at lower prices.