Fossil fuel facilities exergy return for a frontier of analysis incorporating CO2 capture: The case of a coal power plant

The Energy Return On Investment (EROI) has proven to be an useful concept in the last 50 years. However, given the urgent need of the energy transition to deal with climate change, its frontier of application and concept must be extended to include the requirement for CO2 capture from fossil fuel combustion (or the exergy associated with this work). This study applies a novel concept, the Exergy Return on Environment and Energy Investment (ExROEEI). It considers the quality of energy and extends the frontier of analysis to incorporate the exergy associated with removing CO2 from fuel combustion and with the environmental effects of effluent streams. This allows assessing fossil fuel sources that are converted to meet energy services but have to comply with the need to limit CO2 emissions. By applying this extended concept to a coal-based power plant equipped with aminebased post-combustion CO2 capture, our findings show that the ExROEEI reaches a 2.06:1 ratio, being the outlet exergy of the plant 250.52 PJ and its inlet exergy 121.46 PJ (the exergy associated with capturing and compressing the CO2 represents 35.58% of this figure). Therefore, the exergy surplus of this option is lower, which raises questions about its energy feasibility.