HUNTINGTON, Emery County — As the number of workers who mine coal across the United States continues to dwindle as mines close under the weight of environmental scrutiny, so go the power plants that feed on the coal.

The Carbon Power Plant outside of Helper shut down in April, in large part a casualty of a new mercury emissions standard put out by the U.S. Environmental Protection Agency three years ago.

Coal-fired power plants are shutting down across the country due to their pollution profile and pressure from lawsuits, while others are transitioning to natural gas because of the fuel's abundance, its low cost and its cleaner emissions footprint.

Since the implementation of the Clean Air Act in 1970, the EPA has been releasing regulations over time designed to decrease emissions from nitrogen oxides, sulfur dioxide and now with the first mercury standard that proved problematic for older plants, such as the 60-year-old Carbon plant.

Although the rule has since been overturned by the courts — which said the federal agency failed to apply a rigorous cost benefits analysis — the fate of the Carbon plant was already sealed.

With that closure still freshly in view, the EPA came out this August with its most stringent set of regulations in history aimed at existing power plants — President Barack Obama's Clean Power Plan.

Hailed by environmental groups and lambasted by conservatives and industry, the plan is designed to reduce greenhouse gas emissions by 32 percent from 2005 levels by 2030, carbon pollution scientists say is responsible for climate change.

In the United States, power plants are the single largest source of those U.S. greenhouse gas emissions, contributing to a third, according to the EPA.

Gary Herbert's view

Utah Gov. Gary Herbert's administration has argued strenuously against the plan, asserting like other coal-dependent states that the federal agency lacks the legal authority to implement such sweeping rules, which also fail to take in states' unique circumstances.

Earlier this month, more than a dozen states filed suit against the EPA to strike down the plan, hoping that justices will apply a similar reasoning to the decision that ultimately overturned the mercury standard. Utah is not among those states involved in the lawsuit, but it could climb on board as the ramifications become more clear.

Carbon County Commissioner Jae Potter said the Clean Power Plan, if allowed to stand, will forever change life in Utah's coal country and for the state's ratepayers.

"It will be a devastating blow to our economy as we know it. It takes down something that benefits not just us, but the Wasatch Front and the entire state."

With mounting environmental pressure and weak coal markets, about 200 power plants across the country have already either been retired or are scheduled for closure — out of a fleet of 530.

The EPA, even before it put its final touches on the Clean Power Plan, estimated that thermal coal production will decline by roughly 26 percent as a result of the new rules.

An analysis by the American Coalition for Clean Coal Electricity — a coal industry advocacy organization — said EPA policies were cited as a factor in the closure or pending closure of 389 coal-fired units in 36 states that provided 61,000 megawatts of electricity, or enough to power 15.5 million homes.

Coal-fired power plants are being pressured into closure by the Sierra Club's Beyond Coal Campaign, which some observe is the organization's most successful and expensive endeavor in its more than 100-year history.

Aging coal-fired power plants, critics say, are a dinosaur that should have been extinct long ago.

"Coal powered the past, but there's no place for it in the future, " said HEAL Utah's executive director Matt Pacenza. "We've learned far too much about how it sickens our families, obscures our scenic vistas and is dangerously warming our planet. We have better alternatives, including using less energy and moving boldly to invest in the wind and solar power that Utah has in such bounty."

Utah is not to the point where wind and solar can meet the state's energy needs and ensure the reliability of the base load for the power grid, but Panceza said the state needs to move as quickly as possible to a system that relies on energy efficiency, renewables and uses natural gas as a "bridge" fuel.

In Utah, lawsuits by HEAL Utah and other groups has targeted existing power plants over pollution and what they say is outdated pollution technology that fails to adequately capture those emissions.

Just last week, the Sierra Club and HEAL Utah urged the Public Service Commission to reject Rocky Mountain Power's blueprint for energy over the next two decades, with accusations that it locks Utah into a future with "dirty, outdated coal-fired power plants," and gives short notice to renewables.

Industry pushes back

Darrell Cunningham, managing director of the Huntington plant owned by Rocky Mountain Power's parent company, PacifiCorp, is clearly frustrated with the complaints.

He has spent his career at the company's trio of Utah power plants, witnessing firsthand an expensive transformation to cleaner burning machinery.

At Huntington, the company added a scrubber in 2006 and, five years later, installed a bag house — a $100 million investment to decrease emissions.

The scrubber uses lime to absorb the sulfur dioxide, effectively eliminating 90 percent of those emissions, he said.

Four gigantic yellow towers make up the scrubber and particulate emissions from the plant are monitored 24 hours a day, seven days a week.

In the bag house, dirty air is filtered through 514 bags in eight compartments, with those bags measuring 28-feet tall.

"Obviously I see our reliance on coal decreasing over the years, but there is a lot here for a company to walk away from. We've been able to produce electricity at a very low rate and the costs of turning that away are great...there has to be middle ground."

Critics of the Clean Power Plan say it will drive electricity rates to a minimum of 7 cents more per kilowatt-hour — a cost that could be even higher for coal-rich states like Utah.

But Rocky Mountain Power officials believe Utah may not be as hard-hit as the plan's opponents predict, still cautioning that a review of the impacts is in play.

The utility company is already making changes absent the effects of the new EPA regulations.

Spokesman Paul Murphy said the company plans to close or convert 10 coal-fired power units across its fleet to natural gas between 2015 and 2029 and reduce its coal generation from current levels by 40 percent by 2034.

He said the company hopes to keep the Hunter power plant operational into 2030 and Huntington in 2042 — both years that mark the end of the plants' regulatory life. Both of them could continue to operate past that, or be retired early in the face of regulations. Overall, the company has invested about $500 million in pollution technology and upgrades at its Utah power plants since 2005.

A recent Envision Utah poll on possible scenarios for Utah's energy consumption in 2050 indicates the residents want more clean energy in the mix but those results also back Herbert's assertion that the transition has to come over time, without drastic price increases.

That phased-in approach may buy Utah's coal-fired power plants more time, or alternately, more advances in solar and wind technology could accelerate the transition and their demise.

Whatever energy source is in play, Rocky Mountain Power spokesman Dave Eskelsen said there's not a way to avoid any kind of environmental consequences.

"There is not a way to generate the amount of electricity we use as a society without environmental impact, whether it is coal, natural gas, wind, solar, biofuels or geothermal," he said. "There's just not."

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