Life Cycle Assessment for supercritical pulverized coal power plants with post-combustion carbon capture and storage

Abstract

Environmental and technical aspects of four supercritical (SC) pulverized-coal processes with post-combustion carbon capture and storage (CCS) are evaluated in the present work. The post-combustion CCS technologies (e.g. MDEA, aqueous ammonia and Calcium Looping (CaL) are compared to the benchmark case represented by the SC pulverized coal without CCS). Some important key performance indicators (e.g. net electrical power, energy conversion efficiency, carbon capture rate, specific CO2 emissions, SPECCA) are calculated based on process modeling and simulation data. The focus of the present work lies in the environmental evaluation, using the Life Cycle Analysis (LCA) methodology, of the processes considered. The system boundaries include: i) power production from coal coupled to energy efficient CCS technologies based on post-combustion capture; ii) upstream processes such as extraction and processing of coal, limestone, solvents used post-combustion CCS, as well as power plant, coal mine, CO2 pipelines construction and commissioning and iii) downstream processes: CO2 compression, transport and storage (for the CCS case) as well as power plant, CCS units, coal mine and CO2 pipelines decommissioning. GaBi6 software was used to perform a “cradle-to-grave” LCA study, to calculate and compare different impact categories, according to CML 2001 impact assessment method. All results are reported to one MWh of net energy produced in the power plant. Discussions about the most significant environmental impact categories are reported leading to the conclusions that the introduction of the CCS technologies decreases the global warming potential (GWP) indicator, but all the other environmental categories increase with respect to the benchmark case. There is also a competition between the aqueous ammonia adsorption and CaL for some impact categories (other than GWP). The implementation of these new CCS technologies is more favorable than the traditional amine-based CO2 capture.