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Dave Johnston Power Plant

Coal is moved after being transported to the Dave Johnston Power Plant via conveyor in Glenrock. The plant has added several emission control processes over the years of its operation to keep up with increasingly strict regulations. 

The largest utility in Wyoming, the country's top coal-producing state, envisions a future less reliant on the carbon-rich mineral. 

Rocky Mountain Power said Monday it intends to gradually shift away from coal-fired power generation over the next two decades, using more natural gas, wind and energy efficiency measures to meet consumers' needs. 

“One of the ways our industry is changing is a gradual, orderly transition away from coal to produce electricity," said Rocky Mountain Power CEO Cindy Crane in a statement. "In recent years, the company has built new natural gas plants and wind power projects and expanded energy efficiency programs."

Monday's announcement in many ways vocalized a dynamic already in place for years. Rocky Mountain Power retired the 172-megawatt Carbon Power Plant near Helper, Utah, in April. Lake Side Power Station, a 545-megawatt natural gas plant in Vineyard, Utah, is replacing the former coal plant. 

Observers said it will likely have little impact on Wyoming's coal miners. Rocky Mountain Power consumes a small fraction of the coal mined in Wyoming today. 

Crain's statement nonetheless underscored the wider shift away from coal nationally. Roughly 13 gigawatts of coal-fired generation are expected to be retired in 2015, according to the U.S. Energy Information Administration. By contrast, utilities nationwide are adding 9.8 gigawatts of wind, 6.3 gigawatts of natural gas and 1.6 gigawatts of solar. 

The trend highlighted the difficult reality facing Wyoming, which accounts for roughly 40 percent of the country's coal production and relies on the industry as an important source of tax revenue and jobs. 

Utilities are loathe to build new coal plants in light of tightening federal air quality standards, said Robert Godby, an economics professor specializing in power generation at the University of Wyoming. Rocky Mountain Power is effectively saying it will replace its coal-fired units with other forms of power when its aging plants reach their retirement dates, he noted. 

"Coal is an increasingly challenged fuel source," Godby said. "That regulation makes coal power more expensive at a time when natural gas and renewable generation has become cheaper. You add to that potential future regulations and you can you see why a company would not be investing in coal."

Rocky Mountain Power, a subsidiary of Oregon-based PacifiCorp, serves 1.8 million customers in six western states. The majority of them are in Idaho, Utah and Wyoming. 

Coal generation accounts for 60 percent of Rocky Mountain Power's electricity production today, followed by natural gas (14 percent) and renewables (9 percent). 

The utility anticipates coal will make up almost 50 percent of its generation by 2025. Gas and renewables are expected to generate 21 percent and 12 percent of the company's power, respectively.

The Integrated Resource Plan announced Monday is essentially a road map, detailing what fuel sources the utility expects to use in the coming years. The plan does not call for new power plant construction within the next decade.  However, it does expect the company will buy additional wind and solar power built by independent producers.

Energy efficiency measures are one of the major focal points of the plan. In 2014 alone, the utility said efficiency programs saved 553,200 megawatt-hours of electricity, or enough to power Casper, Laramie, Rock Springs and Riverton combined. 

Many of the plant closings or conversions outlined in the plan have already been announced. Four units at Dave Johnston in Glenrock are set to close in 2027, the year they were scheduled to be retired. One unit at the Naughton plant in Kemmerer will be converted to gas by 2018. Three units there will be retired in 2029. 

David Eskelsen, a Rocky Mountain Power spokesman, said the utility's coal-fired plants have long served its customers with reliable, low-cost power. Many of those plants will continue to operate for years, he said, noting most of the scheduled retirements are between 2030 and 2040. 

But new federal air quality regulations mean that natural gas and renewables represent less of a risk to the company's customers going forward, he said.

"Absent some technological advance we can’t yet see, it is impractical in the current regulatory environment to build a new coal plant," Eskelsen said. 

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