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The big switch: utilities' conversion from coal to natural gas

The big switch: utilities' conversion from coal to natural gas

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The vast rooms of PacifiCorp’s Naughton plant outside Kemmerer are filled with great reverberating pipes and roaring turbines stretching the length of a football field. The control room, by comparison, is eerily silent. Operators there monitor a bank of computer screens tracking the temperature and pressure and the power being produced at any given moment within the giant coal-fired plant.

“Electricity is the only product I know of that has to be manufactured and delivered in the same moment the consumer demands it,” said Dave Eskelsen, a PacifiCorp spokesman.

Naughton burns 8,103 tons of coal daily to meet that demand, producing 687 megawatts of electricity. But on Dec. 31, 2017, the southwestern Wyoming plant will shut down the largest of its three coal-fired units. The plant will turn the unit on again six months later, only this time it will be operating on natural gas.

The 20 coal burners, spread out over the plant’s five floors, will be switched out for the type that can burn natural gas. Pulverizers used to crush coal into powder and scrubbers made to remove sulfur dioxide from the plant’s emissions stream will be decommissioned but left in place. Naughton will no longer truck water to the plant from the nearby trona mines.

The number of full-time employees will fall from 152 to 112. The neighboring mine, which feeds the plant coal, could lose another 100 jobs if it can’t replace that demand.

Naughton is not unique in this. Utilities across the country are switching away from coal in favor of natural gas, converting old coal-fired units to natural gas or retiring old coal plants in favor of new natural gas ones.

Today, 60 percent of the electricity PacifiCorp sends to customers is produced by coal. Over the next decade, that number is expected to drop to 43 percent.

The U.S. Energy Information Administration’s 2014 Annual Energy Outlook estimates coal will provide 41 percent of the nation’s power this year, compared with 27 percent for natural gas and 12 percent for renewable energy. By 2035, the agency predicts natural gas will surpass coal as the country’s largest source of electricity generation.

In part, that’s because of economics. Relatively, low natural gas prices have eaten into coal’s competitiveness. However, regulations also play a role.

The Environmental Protection Agency requires utilities to limit everything from sulfur dioxide and nitrogen oxide emissions to mercury pollution and coal ash.

“It is just too cost-prohibitive to build coal plants that meet current emission requirements,” said Mark Lux, vice president of power delivery at Black Hills Power. The Rapid City-based company is in the midst of decommissioning four coal-fired units in Wyoming, Colorado and South Dakota.

The retirements also signal another trend: Utilities are building few new coal plants. All of the power generation PacifiCorp has added since about 2001 has been either wind energy — about 1,100 megawatts’ worth in Wyoming between 2007 and 2010 — or natural gas, according to Eskelsen.

However, the company still has coal plants with 10 or 20 years of life left. In order to make those older plants meet standards, PacifiCorp has to install expensive equipment to filter out particulate matter and neutralize nitrogen oxide. The Jim Bridger plant, near Rock Springs, is undergoing that process right now.

In other cases, like at the company’s Carbon plant in Utah, it’s economically or practically unfeasible to make the required upgrades. The plant is scheduled to close next year. Nationally, the Energy Information Administration expects about 43 coal-fired plants will close in the next four years.

Naughton is an example of where it is cheaper for utilities to meet EPA’s standards by converting to natural gas.

Physically, it doesn’t take much to change a unit from coal to natural gas, said Naughton plant managing director Shawn Smith. Because natural gas is more expensive, the unit won’t run all the time like it has in the past.

Power fluctuates during the day and with the seasons, Smith explained, so power companies like PacifiCorp run the most economical units, the coal-fired ones, to keep a certain baseline of power available at all times. As demand for electricity increases, the power company adds more units to the grid.

The Naughton plant’s natural gas unit will run only at peak times, probably June through part of September, and during the coldest stretches of the winter, Smith said.

Less operating time means fewer employees, thus the projected job cuts. About half the employees at the plant and mine live in nearby Kemmerer and Diamondville, but some travel from Evanston or Lyman, Smith said.

Natural gas is still more expensive than coal, Smith said, but the price is coming down and becoming more stable. More important, it burns cleaner, which will help the plant stay ahead of the EPA’s regulations.

“Besides controlling emissions, a diversity of resources means more reliability,” Eskelsen, the PacifiCorp spokesman, said. “It reduces risk.”

Reach Tom Dixon at 307-266-0616 or Follow him on Twitter: @DixonTrib.


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