It’s Where Your Power Comes From

By Cary Snyder

By Cary Snyder

csnyder@wyomingnews.com

GILLETTE – The site of the nearly 400-acre Wyodak Mine means something different to everyone.

For passing westbound motorists on Interstate 90, it’s a welcome change in the barren landscape that lets them know they are approaching Gillette, the largest town in northeast Wyoming.

For some workers, it’s an office where they continue lengthy careers in the mining industry.

For most residents of Laramie County, many of whom will never see the mine and its adjacent power plants in person, it is the source of their electricity.

The Wyodak Mine sits on the Powder River Basin, which stretches into Montana and contains one of the most plentiful reservoirs of coal in the country. By some estimates, 40 percent of the coal burned in the United States comes from the basin.

The mine has about 280 million tons of coal in reserve, which Black Hills Corp. officials say is enough to keep producing electricity at its nearby power plants for the next half-century.

See WYGEN, page A9

WYGEN

Continued from A1

The process that turns coal into the power source for Cheyenne Light, Fuel and Power customers starts anywhere from 90 to 300 feet below the ground just north of the interstate.

The natural resource is dug up from beneath the surface and put on a conveyor belt that runs underneath the highway where it enters one of several plants.

From there, through a process that is constantly being monitored to improve efficiency and prepare for the expectation that the federal government in years ahead will impose stricter regulations on emissions to safeguard the environment, coal is transformed into electricity. It is then transmitted more than 200 miles south to power the Capital City.

History of Wygen II

Black Hills Corp. bought Cheyenne Light from Xcel Energy Inc. in January 2005. Since then, customers in the greater Cheyenne area have been receiving electricity under an agreement with the Public Service Company of Colorado.

That changed Jan. 1, company officials say, when Wygen II, a 95- megawatt coal-fired plant, went online without a hitch, the realization of plans that began to develop before the sale was completed.

“From the start, we were searching for an opportunity to build a power plant,” said Mark Stege, general manager of Cheyenne Light.

The process used to produce electricity in Wygen II is not new, but due to advances in technology, it has been made more efficient, officials with the utility say.

The 95 megawatts generated by Wygen II are more than the nearby twin 90-megawatt Wygen I and Neil Simpson II plants, which help make up the facility commonly dubbed the “Wyodak Energy Complex” just south of the highway. Up to 10 percent of Wygen II’s capacity is used to run the plant, said Vern Schild, director of power generation for Black Hills.

Plans are in the works to build Wygen III, likely to have a capacity of 100 megawatts, next to Wygen II. The 20-megawatt Neil Simpson I, named after a longtime Black Hills executive, also sits on the site. Black Hills also has a 20-percent stake in the mammoth 335-megawatt Wyodak Power Plant that is largely owned and operated by PacificCorp.

In addition to Wygen II, Cheyenne Light uses 60 megawatts from Wygen I to supply its energy needs, which has a typical base load of about 135 megawatts, Stege said. Last year, demand peeked at 170 megawatts and in times like that, the utility can use additional available power from a gas-fired turbine near Wygen II.

“Barring the peeks … for the most part, both of those coal- fired plants supply all of our needs,” Stege said.

Cheyenne Light officials say Wygen II will allow for better rate stability because the company will not be as dependent on other market forces that can drive up operating costs.

For example, Stege said transporting coal is often one of the highest costs of manufacturing electricity, but not at Wygen II. Having a coal mine within eyeshot that uses an existing conveyor belt transport system helps duplicate resources, allowing for reduced maintenance and labor costs.

That does not mean customers are not paying for Wygen II, which took 30 months to build at a price tag of about $182 million.

In November, the Public Service Commission of Wyoming approved natural-gas and electric rate hikes for Cheyenne Light customers to cover increased operating expenses, specifically Wygen II. Effective Jan. 1, the typical monthly residential electric bill increased $4.34. The typical residential natural-gas bill increased $10.07.

Getting coal to the plant

As the bird flies, the administration building of the Wyodak Mine is about two miles from Wygen II.

Jim Williams, vice president of Wyodak Resources Development Corp., volunteered to lead a tour of the mine last week, in part so that he could visit with Stege, who was formerly an internal auditor for Black Hills Corp.

After piling into a sport-utility vehicle, it is a short drive on the mine’s network of snow-covered roads to reach the black-tinged man-made gorge carved into the Earth.

In response to a comment that the mine, which grows deeper the farther north it stretches from the highway, is pleasing to look at from a distance, Williams said from the driver’s seat, “Well, do you like money? That’s just black.”

Coal is added to the main conveyor belt at multiple points in the mine. At full speed, the belt that runs under the highway and curves at points travels 1,000 feet per minute, or roughly 12 miles per hour. Williams said the belt propels nearly 4 million tons of coal a year to storage silos near the power plants.

“We only run it (the belt) as long as it takes to fill up the silos,” he said as he drove up a hill from a low point in the mine.

When the belt is shut down, workers perform maintenance on the system. Occasionally, a section of the belt will have to be replaced, but the repair has to be performed quickly so the supply in the silos does not get too low.

If Williams had his way, Black Hills would build another silo to give him more leeway in repairing and maintaining the line. His argument falls short, as Stege points out from the back seat, because none of the plants have yet to be shut down for a lack of coal.

The mine recently shifted from operating on five 8-hour work days to seven, 12-hour days. Williams, who has more than 30 years experience in the industry, said the increased work time will enable the facility to increase the amount of coal it extracts from nearly 4 million tons to as much as 7 million tons.

Some of that coal is transported by truck or rail car to other plants outside of the complex. Black Hills also has power generation plants in Osage, Wyo., and Rapid City, S.D.

How the plant works

Although Wygen II went online Jan.1, it is still considered to be in the testing phase and final touches are being made to parts of its interior. Cheyenne Light was not ready to show off the plant to the public, but instead Schild led a small group on a tour of its cousin, Wygen I, which is nearly identical in how it produces electricity.

The interior of the facility is so loud that Schild had each member of the group wear a headset that was connected to his microphone. Those on the tour could hear him speak, but their voices would fade into the whirl of a boiler, turbine and generator.

Schild said Wygen II burns about 1,500 tons of coal a day, an amount equal to roughly 500,000 tons a year.

Despite its power output, 20 employees are sufficient to operate Wygen II. The vast majority of the plant can be monitored from a control room. During a more than 30-minute walk through Wygen I, only one worker aside from Schild was seen outside of the room.

In announcing the completion of Wygen II, Black Hills touted the facility as among the cleanest coal-fired plants in the country and possibly the first to reduce mercury emissions. Calcium chloride is injected into the coal in a process that Schild said captures between 60 and 70 percent of its mercury.

The coal in the mine is known for its low sulphur content, which inherently helps reduce unwanted byproducts. Black Hills says new burner technology in the plant significantly reduces nitrous oxide emissions below recently-imposed standards.

As coal is brought to the plant, it enters a pulverizer that grinds it to the consistency of baby powder. It is then blown into a 14-story boiler where it produces high-pressure steam at temperatures that Schild said can reach as high as 2,000 degrees Fahrenheit.

The steam is used to turn a turbine generator, which produces electricity that is tied into a power grid from transmission south to Cheyenne.

Most of what is emitted from the plant’s nearly 200-foot tall stack is water vapor, he said. Fly ash, a necessary by-product of the process, is returned to a pit in the mine.

(c) 2008 Wyoming Tribune-Eagle. Provided by ProQuest Information and Learning. All rights Reserved.