May 24, 2006
Advanced Coal Dryer Boosts Power Plant Performance
Latest Project in President's Clean Coal Power Initiative Begins Operations in North Dakota
Washington, DC -
Engineers at a power plant in North Dakota have begun the first continuous operation
of an innovative clean coal technology drying system that uses the plant's excess
heat to wring moisture from the incoming coal.
Initial results from Great River Energy's Coal Creek Station in Underwood, ND,
are showing that the system could be the first to demonstrate that pre-drying
high-moisture coals before they are fed to a power plant's boiler offers a practical
and economical way to generate more power from a lower quantity of coal and reduce
"Enhancing the fuel value of high moisture coals is critically important," said
Jeffrey Jarrett, Assistant Secretary for Fossil Energy. "If we are to reduce
our dependence on foreign sources of energy, we must make the most of our abundant
coal resources here at home."
The results could benefit power plants that today generate more than 100,000
megawatts of electricity in the United States by burning high-moisture coals. The
279 units that burn these types of coal currently account for nearly a third
of the electric power generated in the United States from coal.
The project is the latest in the U.S. Department of Energy's Clean Coal Power
Initiative to move from the design and construction phase into full-scale operations. President
Bush authorized the program shortly after taking office as part of a $2 billion,
10-year commitment to pioneer new coal technologies that could reduce air pollutants
and slow the buildup of greenhouse gases. The $31.5 million Great River Energy
project - $13.5 million of which is being funded by the Energy Department - was
one of the projects selected in the program's opening round of competition in
In the first phase of the project, a dryer system was designed and constructed
to dry about one-fourth of the coal fed to a 546-megawatt (MW) unit. Successful
operation of the first dryer would facilitate GRE proceeding to commercial demonstration
in 2007, which involves final design and construction of a full set of dryers
for the complete 546 MW coal-fired unit.
The technology is likely to prove especially beneficial to power plants that
burn lignite and Powder River Basin coals, both of which create operational challenges
because of their high moisture content. The lignite entering the Coal Creek
Station, for example, can be as much as 40 percent water measured by its weight.
Until now, however, the cost of thermally drying these coals has often outweighed
any potential gains in the plant's operational performance. The Coal Creek
Station's approach of capturing and reusing the excess heat - rather than burning
additional fuel to generate heat - is proving to be the key to making thermal
coal drying commercially practical.
Drying the coal increases its heating value, and that means that less coal is
needed to generate the same amount of energy. Less flue gas is also emitted which
reduces the workload on other equipment in the plant, such as fans. The
result is an estimated increase in efficiency at the Coal Creek Station of about
5 percent - a very significant improvement in plant performance and cost savings.
The first dryer has been supplying processed lignite to one of the seven pulverizers
for a 546 MW unit at the station for several weeks. Early estimates show that
with just one pulverizer using dried coal, the stack flow rate from the unit
decreased one percent, boiler efficiency increased 0.3 percentage points, pulverizer
power consumption decreased 4.5 percent, sulfur oxide emissions fell 2.0 percent,
nitrogen oxide emissions decreased 8.5 percent, and carbon dioxide emissions
decreased 0.34 percent.
As part of the public-private clean coal technology partnership, the full set
of dryers, scheduled to be built in 2007 will operate through 2008 to generate
data that could be applied to other high-moisture, coal-burning power plants
that operate primarily in western coal regions of the United States and in several
other countries. After that, the unit is expected to continue operating
as part of the power station's commercial operations.
Along with Great River Energy, partners in the project include the Electric Power
Research Institute (Palo Alto, CA), Lehigh University (Bethlehem, PA), Barr Engineering
(Minneapolis, MN), Heyl & Patterson (Pittsburgh, PA), Headwaters Energy
Services (South Jordan, UT), and Falkirk Mining and Couteau Properties (Underwood,
Contact: David Anna, DOE/NETL, 412-386-4646