Coal power decarbonization via biomass co-firing with carbon capture and storage: Tradeoff between exergy loss and GHG reduction

Co-firing of coal and biomass is a feasible pathway for low-or even negative-carbon transformation of power sector in countries that rely on coal. There are two main kinds of coal and biomass co-firing pathways: biomass gasification co-firing with pulverized coal (BGCPC) and biomass direct co-firing with pulverized coal (BDCPC). However, few attentions have been paid to the comparative study of techno-environmental assessments for the above two main technologies with or without carbon capture and storage (CCS). Here we present a comparative system evaluation framework based on chemical simulation and life cycle assessment (LCA) to compare the energy performances and environmental impacts of different biomass co-firing and CCS technology combina-tions. A new metric, global warming potential of per unit exergy efficiency loss (GWPUEL) is proposed to reveal the trade-off between greenhouse gas (GHG) emission abatement and exergy efficiency loss. Results show that BGCPC-CCS units of all capacities can achieve negative life-cycle GHG emissions under 25% co-firing ratio scenario, but only 1000 MW BDCPC-CCS units can achieve near-zero life-cycle GHG emissions. Though 300 MW units show the minimum carbon reduction potential among all the selected capacities, they can achieve the most promising GWPUEL benefits for their mild exergy efficiency loss after CCS retrofit. This indicator provides a comprehensive viewpoint to weigh the compromise between energy performance and environmental burdens of different bio-based and CCS technology combinations, further facilitating various decarbonization schemes of global power sector under the carbon neutrality target.