The U.S. power sector is increasingly shifting to refined coal and now makes up nearly one-fifth of coal-based generation.
Use increased from 17 percent in 2016 to 19 percent through the end of the third quarter of 2017, according to the U.S. Energy Information Administration.
Refined coal has been processed to remove certain pollutants from raw – or feedstock – coal. Electricity generators fueled by refined coal can produce fewer emissions than those fueled by feedstock coal alone.
Great River Energy has been using refined coal since December 2009 via its DryFiningTM fuel enhancement process, which refines or beneficiates lignite coal through a thermal drying and mechanical segregation process. Drying utilizes residual or waste heat to raise the heating value of the coal per pound. The refining component segregates the lignite stream and removes the higher density compounds that contain higher levels of sulfur and mercury.
In the United States, refined coal is most commonly made by mixing proprietary additives to feedstock coal. These additives contain a mixture of halogens (e.g., bromine or chlorine) and metals to increase the production of mercury oxides. Oxidized mercury can be captured by using mercury emission reduction technologies such as flue gas desulfurization scrubbers and particulate matter control systems. Oxidized mercury can also be adsorbed by powder-activated carbon injection and captured by particulate matter control systems.
Coal Creek Station utilizes about 6.0 million tons of DryFineTM coal annually, while Spiritwood Station utilizes about 275,000 tons of DryFine coal annually.