Cost-effective ultra-high CO2 capture rates for combined cycle gas turbines with monoethanolamine solvent

Natural gas is expected to remain an important power generation fuel for the foreseeable future, but ultra-high CO2 capture rates near 100% are required to achieve life cycle greenhouse gas (GHG) emissions consistent with net-zero ambitions. Recent studies have found that the marginal cost of abating low concentration CO2 sources, such as combined cycle gas turbines (CCGTs), with monoethanolamine (MEA) solvent increases dramatically as the capture rate approaches 100%. Yet the assumed process design conditions were suboptimal for minimising CO2 capture cost for low concentration sources. We perform detailed techno-economic assessments combined with life cycle analyses evaluating the impact of key process design variables for CCGTs with MEA-based CO2 capture and develop guidelines to determine optimal design parameters to minimise the cost of avoided CO2 emissions at ultra-high capture rates. We show that, with optimal lean solvent loading and regenerator operating conditions, 99.5% of fossil-CO2 direct emissions could be captured with marginal cost of avoided CO2 (MCAC) of 164 USD/tCO2, while MCAC for 100% fossil-CO2 capture is 271 USD/tCO2. MCAC calculated in this study for 100% fossil-CO2 capture with optimal process conditions is c. 50% lower than in previous studies, establishing a new performance benchmark for ultra-high CO2 capture. We also show that marginal cost of avoided cradle-to-gate life cycle GHG emissions is only 3–9% higher than MCAC for 96–100% fossil-CO2 capture. Cost-effective ultra-high capture from CCGTs is particularly significant for achieving climate change mitigation goals given high current costs for permanent atmospheric CO2 removal, and highly uncertain future costs.