Comparative assessment of water use and environmental implications of coal slurry pipelines

With other studies conducted by the U.S. Geological Survey of water use in the conversion and transportation of the West 's coal, an analysis of water use and environmental implications of coal-slurry pipeline transport is presented. Simulations of a hypothetical slurry pipeline of 1000-mile length transporting 12.5 million tons per year indicate that pipeline costs and energy requirements are quite sensitive to the coal-to-water ratio. For realistic water prices, the optimal ratio will not vary far from the 50/50 ratio by weight. In comparison to other methods of energy conversion and transport, coal-slurry pipeline utilize about 1/3 the amount of water required for coal gasification, and about 1/5 the amount required for on-site electrical generation. An analysis of net energy output from operating alternative energy transportation systems for the assumed conditions indicates that both slurry pipeline and rail shipment require approximately 4.5 percent of the potential electrical energy output of the coal transported, and high-voltage, direct-current transportation requires approximately 6.5 percent. The environmental impacts of the different transports options are so substantially different that a common basis for comparison does not exist. (Woodard-USGS)