Greenhouse Gas Emissions from Coal Gasification Power Generation Systems

Abstract

Life-cycle assessments (LCAs) are computed for coal gasification-based electricity generation technologies for emissions of greenhouse gases (GHGs), principally CO2. Two approaches for computing LCAs are compared for construction and operation of integrated coal-gasification combined-cycle (IGCC) plants: a traditional process-based approach, and one based on economic input-output analysis, called economic input-output life-cycle assessment (EIO-LCA). It is shown that EIO-LCA provides a more complete accounting for emissions incurred during construction, resulting in larger estimates of emissions. For plant construction, process-based LCA computes emissions that approximate a subset of emissions computed via the EIO-LCA method. For plant operation, however, only emissions due to mining and consumption of coal at the plant are significant, and both methods of analysis give essentially equivalent results. For conventional coal-based power generators, and even for those that would capture 90% of carbon emissions, GHG emissions during a typical operating life of 30 to 50 years dominate the life cycle. Literature values for life-cycle emissions of GHGs for a number of renewable technologies are compared to emissions from IGCC systems with and without carbon capture and from natural gas combined cycle (NGCC) systems without capture. Lowest life-cycle emissions are achieved with dammed hydropower and wind farms. IGCC with 90% CO2 capture exhibits lower life-cycle GHG emissions than NGCC and solar photovoltaic systems.