GRE puts plant on standbyThe steam and electricity generated this fall at Great River Energy’s Spiritwood Station will be short lived. Staff at the plant has started the commissioning process, which will lead to a roughly 60-day run this fall before shutting down the plant.
By: Keith Norman, The Jamestown Sun
SPIRITWOOD, N.D. — The steam and electricity generated this fall at Great River Energy’s Spiritwood Station will be short lived. Staff at the plant has started the commissioning process, which will lead to a roughly 60-day run this fall before shutting down the plant.
“Our plans are to not operate the plant for 2012 because the price for electricity is down and doesn’t allow us to operate,” said Lyndon Anderson, communications specialist for Great River Energy. “The unit will be in standby mode until the market improves.”
Anderson said the plant can produce steam for its customers with its smaller, natural gas-powered boilers if they request it. The plant is connected to the nearby Cargill Malting Plant. An ethanol plant is also planned by GRE on the land located west of Spiritwood Station. If the ethanol plant is constructed, it would also use steam from Spiritwood Station as energy.
“The MISO market is down,” said Paul Solomonson, leader of plant engineering for Spiritwood Station. “A lot is due to the recession. Demand is reduced and with that you have lower prices.”
MISO is Midwest Independent Transmission System Operator, a nonprofit organization that maintains the power grid from Manitoba to the Chicago area.
In the meantime, the staff will use this fall’s run to fine tune the systems and check out the equipment.
“We wanted to tune the boiler to run properly,” Solomonson said. “We want to be ready to go on a short notice if called upon. We also need to finish the construction process and verify that every system is operating correctly.”
The heart of the Spiritwood Station is the coal-fired boiler. This 8-story-tall structure is located at the main building of generating plant. The boiler will burn a patented fuel called DryFine, developed by GRE, based on North Dakota lignite.
“Lignite coal from the mine is relatively high in moisture,” Solomonson said. “The coal from the Falkirk mine is about 38 percent moisture. We dry it down to about 25 percent.”
The process also removes some of the impurities from the coal and grinds it into a consistent pea size. By removing the impurities, emissions are reduced.
“The energy in a pound of coal increases from 6,200 Btu (British thermal units) to 7,500 Btu,” Solomonson said. “It burns hotter and takes less coal to operate.”
Even burning the more efficient DryFine coal, the plant consumes a lot of coal.
“We burn 73 tons of DryFine per hour under full load and 44 tons per hour under minimum load,” Anderson said.
The coal is delivered by rail in batches of 50 cars each carrying 100 tons of coal. Each delivery will operate the plant about five days under minimum load.
Another system the crews will tune is the emissions-control portion of the plant. These controls are in addition to the reduction in emissions attributed to burning DryFine.
“This plant has added features to reduce nitrogen dioxide,” Solomonson said. “We inject limestone into the unit for sulfur dioxide reductions and we have the conventional scrubber and bagger.”
The bagger building includes large bags similar to vacuum cleaner bags that accumulate particles but allow air to pass through. Some of the fly ash that accumulates in the bags is fed back into the boiler while the rest is sold for use in construction and other industries.
“Most of what you see emitted is water vapor,” Solomonson said. “We have continuous emissions monitoring. We have to file that information with the EPA.”
The plant will also occasionally vent the steam created by the boiler.
“If something goes wrong and there is no place for the energy to go, it vents out the roof of the building,” Solomonson said. “Early this summer a tornado damaged a transmission line in Minnesota and it caused the plants in western North Dakota to vent steam because there was no place for the electricity to go.”
The venting sounds similar to a jet plane taking off at an airport, he said. This sound may also occur during the testing and tuning over coming months.
Anderson said the Spiritwood Station is the first coal-fired generating plant built by GRE in North Dakota in 25 years.
“It’s the newest plant with all the latest emissions technology,” he said.
Construction on the $350 million Spiritwood Station began in 2006 with the plant originally intended to go online in 2010. About 15 employees will maintain it while it is on standby.
Sun reporter Keith Norman can be reached at 701-952-8452 or by email at email@example.com