Environmental impacts of a chemical looping combustion plant with a negative emission using bark as a feedstock

Chemical looping combustion (CLC) is a promising carbon capture technology for clean energy production in the form of combined heat and power (CHP). This study conducts a comprehensive environmental impact assessment via life cycle assessment (LCA) of the CLC technology for CHP production, utilizing waste bark from the four geographical locations of pulp and paper industry with the functional unit of 1 MWh exergy output from the plant. To facilitate a comparative LCA of the CLC plant, conventional CHP plant with and without postcombustion capture is also examined in this study. Analyzing four geographical locations, the study highlights the significant reduction in global warming potential (GWP) achieved through post-combustion CO2 capture, from 679.58 to 77.56 kg CO2-eq/MWh, and further to 15.51 kg CO2-eq/MWh when CLC is integrated (when biogenic emissions are counted). The CLC plant leads to net negative emissions from -465.83 to -596.93 kg CO2-eq/MWh when biogenic emissions are not accounted. The highest emissions in CLC systems come from CO2 compression and transportation. A sensitivity analysis is also conducted to study the effect of lifetime of the oxygen carrier on GWP. Results showed that the lifespan of the oxygen carrier greatly influences the GWP up to 1400 hours, after which further extensions have minimal effect. While carbon capture and storage (CCS) reduces greenhouse gases, it increases other impacts like resource use and toxicity due to energy demands and CO2 transport risks. The research underscores the need for location-specific assessments to optimize the sustainability of CLC and CCS technologies.