CONVERSION OF DOMESTIC COAL AND BIOMASS RESOURCES INTO POWER WITH NET ZERO LIFECYCLE GREENHOUSE GAS EMISSIONS (34tif)

摘要

Recent concern of Greenhouse Gas (GHG) emissions from coal-fired power plants, specifically carbon dioxide (CO_2), has prompted the power generation industry to explore new ways to reduce carbon dioxide emissions while maintaining current levels of power plant efficiency and output. The National Energy Technology Laboratory (NETL) initiated this study to analyze the impact of reducing the GHG emissions from coal-fired power plants by co-feeding switchgrass along with coal into an Integrated Gasification Combined Cycle (IGCC) plant. Co-firing biomass along with coal has been demonstrated and may allow coal, the most abundant and secure energy resource in the United States, to maintain its role in the US power supply but in a more advantageous, environmentally friendly way. This study shows that, at demonstrated levels of biomass feed percentage, a net zero limited lifecycle GHG footprint is viable for coal and switchgrass power generation when using state of the art technology. Co-firing biomass with coal allows the CO_2 emissions caused by burning biomass to be considered GHG-neutral. The photosynthetic process removes atmospheric CO_2 and fixes it to a growing biomass feedstock; therefore CO_2 emissions from biomass combustion do not contribute to the net accumulation of atmospheric CO_2. However, the cultivation,harvesting and delivery processes to provide both coal and biomass feedstocks utilize fossil fuels and so produce emissions that cannot be considered GHG-neutral. These fossil fuel-related emissions must be considered when evaluating lifecycle greenhouse gas emissions to gain a thorough understanding of the GHG footprint of power generation. This study examines the emissions of CO_2 and other GHGs resulting from the production, transportation and combustion of the coal and biomass fuel to provide a limited GHG lifecycle analysis of the process. This report provides an assessment of the technical, economic arid environmental performance of coal and biomass-fed IGCC plants. Each case in the study will use varying proportions of Illinois #6 or Montana Rosebud Powder River Basin coal and switchgrass as feed to produce approximately 550 MW of GHG-neutral power.