The Great Plains Synfuels Plant
The Great Plains Synfuels Plant near Beulah, North Dakota, operated by the Dakota Gasification Company, may provide a hint of an important future use for coal in the United States—the production of synthetic liquid and gaseous fuels. The plant was built with government support over two decades ago during a time of high oil prices and natural gas shortages. Each day, it uses 18,000 tons of lignite to produce about 160 million standard cubic feet of methane gas. It also produces about the same amount of CO2, which is captured and piped 200 miles north to Saskatchewan, Canada, where it is used for enhanced oil recovery (EOR) in the Weyburn Field. An additional, roughly comparable amount of CO2 is discharged to the atmosphere. The plant also produces anhydrous ammonia and ammonium sulfate for agricultural use, as well as a variety of other minor products. With the high price of natural gas over the past several years, the plant has been profitable and is paying off its debt to the federal government.
The Great Plains Synfuels Plant is a minemouth plant with an associated power plant. Water for the plant is pumped from the Missouri River, 20 miles to the north. The plant employs oxygen and steam-blown Lurgi gasifiers of the type used by Sasol in South Africa. Compared to natural gas from a conventional gas well, the Great Plains plant emits about twice as much CO2 to the atmosphere per British thermal unit (Btu) of methane produced, even after subtracting the CO2 captured and used for EOR (but including the carbon contained in the methane product). The CO2 emitted from a coal conversion plant can be reduced to a negligible quantity if hydrogen and electricity are the co-products (rather than methane or liquid fuels) and if all of the carbon dioxide is captured and sequestered (as is planned by the Department of Energy for the FutureGen plant; see p. 101-102).
A number of studies have analyzed longer-term scenarios—to 2050 and beyond—in which coal to liquids, coal to substitute natural gas, and coal to hydrogen might begin to play increasingly important roles in the U.S. and global energy economies (e.g., IPCC, 2001; NRC, 2004a). There remains significant uncertainty, however, about these (or other) longer-term scenarios. In the time frame specified for the current study, to 2030, the scenarios reviewed in Chapter 2 suggest that power generation will remain the dominant use of coal. The remainder of this chapter focuses on issues associated with this use of coal.
Coal-based power plants emit air pollutants and create solid and liquid wastes that can adversely affect air quality, terrestrial and aquatic environments, water resources, human health, and climate. Environmental management technologies that are already widely available and in use can reduce most of these