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 GRE is DryFiningTM for a better, drier lignite future Posted on 5/31/2010 Affectionately called Great River Energy's "secret sauce" in some circles, the Minnesota-based power cooperative may have struck lignite gold with their patented DryFiningTM process at the Coal Creek Station near Underwood, ND. Being a low-grade coal, lignite is one-third water, but the DryFiningTM process aims to dry the coal, resulting in a better burning and more efficient fuel. "Water entrained in the coal hurts both efficiency and emissions because additional coal is needed to vaporize it (less efficient) and once vaporized it adds to the flue gas volume (emissions)," says Charlie Bullinger, senior principal engineer at Great River Energy's Coal Creek Station. "Nearly half the global reserves are wet." The idea behind DryFiningTM is simple, but developing the best process for drying the coal has been difficult. Research for the process began in 1997. Smaller-scale test projects showed that it was possible to reduce the moisture content of lignite. Those results coupled with more research and tests prompted a partnership with the U.S. Department of Energy (DOE) - a 10-year, $2 billion commitment to clean coal technology through the Clean Coal Power Initiative. "Science developed solutions for other emissions such as acid rain and will deliver on greenhouse gases as well," says Bullinger. "It takes time to come up with reasonable and economical solutions; however, DryFiningTM does provide incremental reductions now." The greatest storyline in the DryFiningTM journey is how it will enhance Coal Creek Station's energy efficiency and decrease the output of stack emissions. The process is expected to reduce the moisture content of lignite from 37 percent down to 28 percent and increase the British thermal units (BTUs) content of lignite from 6,200 BTUs to 7,100. While the energy value of the lignite is being increased, stack emissions will be greatly reduced. Carbon dioxide will be reduced by 4 percent, sulfur dioxide by more than 40 percent, mercury by more than 40 percent and nitrogen oxide by more than 20 percent. On December 30, 2009, the DryFiningTM system was placed in service, prior to deadline. The nine-story addition to the Coal Creek Station houses eight dryers, each two stories high and required 800 workers last year at the height of its construction. The $31.5 million project was administered by the DOE's Office of Fossil Energy, and managed by the National Energy Technology Laboratory. The project also received funding from the North Dakota Industrial Commission through the Lignite Research Council. The appeal of Great River Energy's process has spanned international borders. "Recently, I chaired a Coal Drying International panel in Australia that included representatives from Asia, Europe, Australia, and the America's. All use lower rank coals and are interested in burning it more efficiently and environmentally friendly," says Bullinger. Great River Energy also plans to use coal that has been through the DryFiningTM process at its Spiritwood Station, which is currently under construction near Jamestown, ND. Great River Energy is the second largest electric utility in Minnesota and serves 28 distribution cooperatives in Minnesota and Wisconsin, who distribute electricity to about 1.7 million people. |
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©2010 Partners for Affordable Energy | |
