“Clean coal” is rapidly becoming more important as energy demands continue to rise.
Clean coal is coal that has been stripped of minerals and other impurities. It is then gasified and burned, and resulting flue gases can be treated with steam and re-burned to make CO2 in the flue gas economically recoverable. The CO2 can then be sequestered for enhanced oil recovery (EOR), enhanced coalbed methane recovery (ECBM) or long-term storage in deep, brine-bearing formations.
One reason why clean coal is so important to the United States is because the coal resource base is enormous.
The United States possesses approximately 6,000 Quads (1015 British Thermal Units [Btu]) of coal resources, which greatly dwarf its 300-Quad resources of oil and gas (figure 1). At current rates of consumption, America has at least another 250 years of coal supply from its resource base of >1,700 billion short tons of measured, indicated and inferred resources (Energy Information Agency).
Coal is central to the U.S. energy economy, accounting for 80,000 direct jobs and supplying 51 percent of the nation’s electricity (Center for Energy Economic Development). More than 300 gigawatts (GW) of electrical capacity in the United States are provided by coal (FutureGen Industrial Alliance).
Moreover, coal is domestically available and -- unlike international oil supplies -- relatively insulated from physical security threats.
Although constructing new conventional coal-fired power plants can meet increasing demands for energy, doing so will lead to increased air pollution, as well as more CO2 in the atmosphere.
Some states, such as California, are unwilling to purchase electricity from plants incapable of controlling greenhouse-gas emissions, which are viewed as contributing to global warming.
(The United States emits approximately 5.7 billion metric tons annually, according to the International Energy Agency.)
Clean coal technology, such as “integrated gasification combined cycle” (IGCC), offers a more efficient and less-polluting alternative than simply pulverizing and burning coal to create electricity. IGCC power plants remove pollutants from coal to create synthetic natural gas (syngas) that drives turbines to produce electricity.
A new industry-government partnership to encourage development and integration of new “clean coal” technologies is “FutureGen,” a $1 billion partnership between the U.S. Department of Energy (DOE), private industry and foreign countries to design, build and operate a 275-megawatt, coal-fueled electricity and hydrogen production power plant with near-zero emissions of SOx and NOx (figure 2).
At least 90 percent of CO2 emissions from the plant (one million tons per year) must be sequestered initially, with a future potential of sequestering nearly 100 percent.
An additional objective is to prove the effectiveness, safety and permanence of CO2 sequestration and to establish protocols for CO2 measuring, monitoring and verification.
Areas suitable for FutureGen facilities must satisfy several technical criteria in four main categories. It must:
- Be at least a 200-acre site with proximity to and capacity for delivery of coal resources.
- Have capacity for injectivity and long-term storage of approximately 50 million tons of CO2 in brine-bearing formations or subsurface coal seams.
- Include the potential for EOR in nearby mature oil fields.
- Have nearby rail facilities and pipelines.
Illinois, Kentucky, North Dakota, Ohio, Texas, West Virginia and Wyoming submitted FutureGen proposals in May 2006. The FutureGen alliance will evaluate the proposals and compile a short list of candidate sites by the end of summer, and DOE will review the sites prior to the alliance’s final selection of a site by summer 2007.
The FutureGen site, which can pave the way for many similar sites to come, will offer a unique opportunity to open new markets for vast U.S.