Release Date: June 6, 2007
|Unique DOE-Funded Coal Dryers Meet Goal of Increased Efficiency, Reduced Emissions
North Dakota Power Station to Expand Use of "Very Successful" Coal-Drying Technology
WASHINGTON, DC - A prototype coal dryer demonstrated at Great River Energy's Coal Creek Station has proven so successful that the power company intends not only to install full-size dryers on the station's 546-megawatt Unit 2 as part of the second phase of its cost-shared project with the U.S. Department of Energy, but also to install the award-winning technology on the 546-megawatt Unit 1 - at its own expense.
The innovative project, which was selected in 2003 under the Office of Fossil Energy's Clean Coal Power Initiative, uses waste heat from the power plant to reduce moisture content in the lignite coal used. This makes it possible to extract more energy from the coal and, at the same time, reduce emissions of mercury, sulfur dioxide, and nitrogen oxides.
"Results from the prototype dryer were very successful, and as a result, we are moving forward and adding four full-scale coal dryers to Unit 2 as part of our cooperative agreement with the Department of Energy," said Charlie Bullinger, senior principal engineer at the Coal Creek Station, located in Underwood, N.D. "In addition, we are planning to go one step further and add four commercial dryers to Unit 1 of Coal Creek Station. This step is outside of the cooperative agreement, and is because of the very positive prototype results and confidence we have in our technology."
Lignite coal, the feedstock fuel for Coal Creek Station's two units, has a high moisture content, containing up to 40 percent water measured by weight. High-moisture coal typically yields lower power efficiency and higher emissions than drier coal; however, the high cost of drying the coal before use has been prohibitive - until now. The technology developed at Coal Creek economically captures and uses the waste heat already being produced by the plant to remove water from the coal. By reducing the moisture content, less coal is required to generate the same amount of electricity, which means fewer emissions and lower emission-control costs.
Great River Energy has already designed a full-scale dryer system that includes four dryers, each capable of processing 135 tons of coal an hour; this will meet the complete fuel needs of Unit 2. The system, currently under construction, will process about 3.75 million tons of raw coal per year. Installation is planned to be completed by March 2008 and will be followed by demonstrations of the integrated system through 2008, providing data useful to other power plants that burn high-moisture coals.
The Energy Department is expected to provide $13.5 million of the $31.5 million needed for the coal-drying project over its 54-month duration. The project is one of eight that were selected in the first round of the Clean Coal Power Initiative, a 10-year, $2-billion program to advance clean coal technologies. The program is managed by the National Energy Technology Laboratory.
In the United States alone, 279 power stations burn high-moisture coals, such as lignite and Powder River Basin subbituminous coal. Together, these plants generate more than 100 gigawatts of electricity - nearly a third of the electric power generated by coal in this country. An additional 100 gigawatts of power is expected to be produced by high-moisture coals over the next 20 years.
If the new coal-drying technology were to be installed in power stations that produce just 10 gigawatts of electric power, it would result in annual emissions reduction of nearly 7,000 tons of nitrogen oxides, more than 18,000 tons of sulfur dioxide, more than 7 million tons of carbon dioxide, more than 9,000 tons of particulates, and nearly 300 pounds of mercury.
This unique dryer design has won several awards including the Lignite Energy Council's Distinguished Service R&D Award, the Electric Power Research Institute's Generation Technology Transfer Award, the American Council of Engineering Companies of Minnesota's 2007 Engineering Excellence Award, and the Minnesota Society of Professional Engineers Award.
In addition to the Great River Energy and the Energy Department, other partners in this CCPI project are Barr Engineering of Minneapolis, Minn.; Heyl & Patterson of Pittsburgh, Pa.; Electric Power Research Institute (EPRI) of Palo Alto, Calif.; Lehigh University of Bethlehem, Pa.; and Falkirk Mining Company of Underwood, N.D.