Jun 7 2010
Great River Energy dedicated its patented DryFining™ coal enhancement system at its generating plant, Coal Creek Station, today.
The system, developed by Great River Energy, uses waste heat to reduce the moisture level of low-rank coal, such as plentiful lignite, which has a moisture content of 38.5 percent. The coal drying component of DryFining reduces the moisture content to approximately 29 percent. The refining component segregates the lignite stream and removes the higher density compounds that contain higher levels of sulfur and mercury; emissions will be reduced by more than 40 percent.
At Coal Creek Station, the DryFining system improves plant operations as the refined coal burns at 7,100 Btus per pound, compared to 6,250 prior to processing. This reduces fuel input into the plant by about 14 percent by weight. Other benefits include:
- A 2-4 percent increase in overall power plant efficiency
- A reduction in stack emissions
- Sulfur dioxide and mercury more than 40 percent
- Nitrogen oxide more than 20 percent
- Carbon dioxide by 4 percent
Coal in wide domestic and international use
More than 15 gigawatts (GW) of electricity is generated in the United States using lignite coal at 35 power plants. An additional 250 domestic units burn high-moisture Powder River Basin coal (100 GW capacity).
“The DryFining system came from the ingenuity of our employees who saw the challenge of high-moisture coal and developed a system that will benefit Great River Energy and our member cooperatives for decades,” said David Saggau, Great River Energy president and CEO. “The system helps coal plants run more efficiently, it helps reduce emissions like SO2, NOX and mercury. The system also helps position utilities to reduce carbon emissions, taking us a step closer to clean coal technology.”
Partnership with U.S. Department of Energy and North Dakota Industrial Commission
Great River Energy developed the technology in partnership with the U.S. Department of Energy (DOE). Originally called the Lignite Fuel Enhancement System, DryFining was selected in round one of the DOE’s Clean Coal Power Initiative in 2003. The initiative was focused on commercial-scale technology demonstrations to continue and expand the use of coal as a fuel source. The project at Coal Creek Station was administered by the DOE’s Office of Fossil Energy and managed by the National Energy Technology Laboratory.
“This unique coal refining system, a successful product of the DOE’s Clean Coal Power Initiative program, enables the nation to tap into vast resources of high-moisture coal while simultaneously providing environmental benefits,” said Thomas Sarkus, deputy director, Office of Major Demonstrations, National Energy Technology Laboratory.
The North Dakota Industrial Commission—through the Lignite Research Council—helped sponsor the initial DryFining technology research, including about $650,000 in three grant rounds. That includes small scale and also 2.5 ton per hour dryer tests. The information learned from those studies—through that partnership with the state of North Dakota—prompted Great River Energy to continue additional research, which eventually led to the final success of the project.
A prototype operation was installed in 2006 and final construction was completed in 2009. Commercial operation began in December 2009.
The DryFining system will be licensed through a partnership with WorleyParsons to coal plants around the world. More than 800 power plants globally use coal to generate electricity, many of which rely on low-rank coal such as lignite. Countries with large amounts of lignite include Australia, New Zealand and Germany.
Lignite coal
Lignite is brownish-black in color and has a high inherent moisture content which can be as high as 66 percent.
The heat content of lignite ranges from 10 to 20 MJ/kg (9 to 17 million Btu per short ton) on a moist, mineral-matter-free basis. The heat content of lignite consumed in the United States averages 13 million Btu/ton (15 MF/kg), on the as-received basis (i.e., containing both inherent moisture and mineral matter).
State official statements
Governor John Hoeven
“Great River Energy’s new drying system demonstrates that through advanced technology North Dakota can continue to provide our nation with more energy at an affordable cost with good environmental stewardship,” said North Dakota Gov. John Hoeven. “North Dakota is proud to have been a partner in the development of this product through the state Industrial Commission’s Lignite Research Program.”
Senator Kent Conrad
“Here at Coal Creek Station you can see real progress on finding cleaner ways to use coal,” Senator Conrad said. “Challenged to find new ways to lower emissions, researchers and engineers at Great River Energy developed an innovative technology to increase lignite’s energy and efficiency while at the same time significantly reducing emissions. This is technology that will impact North Dakota and our nation, and can be utilized on a global scale.”
Senator Byron Dorgan
“Congratulations to Great River Energy on the development of its unique DryFining lignite coal drying technology,” said U.S. Senator Byron Dorgan. “This is a very important milestone for GRE and the lignite industry in North Dakota. GRE has built on the successful public-private technology demonstration, which I supported. It shows another way to utilize coal in a cleaner, more efficient way.”
Congressman Earl Pomeroy
“Today is a big day for Great River Energy. This new technology will help burn our North Dakota coal more cleanly and efficiently, and that’s good for our energy industry and the jobs it supports,” Congressman Pomeroy said. “This new technology is another example of the dynamism and innovation that is a trademark of Great River Energy, and I congratulate them on this new breakthrough.”