Terrestrial Carbon Disturbance from Mountaintop Mining Increases Lifecycle Emissions for Clean Coal

Abstract

The Southern Appalachian forest region of the U.S.--a region responsible for 23% of U.S. coal production--has 24 billion metric tons of high quality coal remaining of which mountaintop coal mining (MCM) will be the primary extraction method. Here we consider greenhouse gas emissions associated with MCM terrestrial disturbance in the life-cycle of coal energy production. We estimate disturbed forest carbon, including terrestrial soil and nonsoil carbon using published U.S. Environmental Protection Agency data of the forest floor removed and U.S. Department of Agriculture--Forest Service inventory data. We estimate the amount of previously buried geogenic organic carbon brought to the soil surface during MCM using published measurements of total organic carbon and carbon isotope data for reclaimed soils, soil organic matter and coal fragments. Contrary to conventional wisdom, the life-cycle emissions of coal production for MCM methods were found to be quite significant when considering the potential terrestrial source. Including terrestrial disturbance in coal life-cycle assessment indicates that indirect emissions are at least 7 and 70% of power plant emissions for conventional and CO(2) capture and sequestration power plants, respectively. To further constrain these estimates, we suggest that the fate of soil carbon and geogenic carbon at MCM sites be explored more widely.