Minnesota power plants cut mercury in half

State is ahead of Legislature’s schedule for pollution controls.

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The Sherco power plant in Becker, Minn.

Photo: GLEN STUBBE, Star Tribune

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Minnesota’s electric power plants have cut their mercury pollution in half since the mid-1990s, putting them three years ahead of the schedule established by the state Legislature and well on their way to meeting new standards set in December by the federal government.

John Linc Stine, commissioner of the Minnesota Pollution Control Agency, on Monday described their success as a “remarkable achievement” that others will follow. The utilities are on track to reduce their mercury emissions to 200 pounds a year by 2016, state and energy officials said — a 90 percent reduction from the volume they generated in the mid-1990s.

“It’s our responsibility to take action and control the destiny of the toxins released in our state,” Stine said at a news conference. “And if we do that, others will learn from our example.”

Mercury, which is produced primarily by coal-fired electrical plants, is a neurotoxin that accumulates in the food chain, and becomes a risk to people primarily through eating certain kinds of fish. A recent study showed that one in 10 infants born on the North Shore of Lake Superior have mercury levels in their blood that are higher than is considered healthy.

Electric utilities, which account for about half of the mercury emitted in Minnesota, will be expected to meet the new federal standards by 2015.

The state’s reduction plan was established in 2006, at a time when the required technology was still brand new. State pollution officials said they were unsure whether the goals could be achieved.

But now the state’s energy companies are using those technologies — and even more advanced techniques in some plants — to remove mercury and other air pollutants before they leave the smokestack, and by retiring some plants and converting others to much cleaner-burning natural gas. Nine generators in Rochester, Burnsville, Schroeder and Hoyt Lakes are being retired or converted to burn natural gas in advance of federal mercury deadline.

Much work ahead

Still, Minnesota has a way to go. The taconite industry is the state’s second-largest producer of mercury, contributing about 30 percent of the total, and it was exempt from Minnesota’s 2006 mercury-reduction law in part because at the time there was no known system for removing it from the blast furnaces. (About one-fourth comes from consumer products like old thermostats and switches in older cars, mercury fillings in people and cremation.)

The taconite industry has only just begun to experiment with systems that will reduce the mercury produced by their processing plants. Frank Kohlasch, the PCA’s air assessment manager, said the taconite companies plan to launch some pilot projects in mercury reduction this year with a grant from the U.S. Environmental Protection Agency.

Craig Pagel, president of the Iron Mining Association of Minnesota, said removing mercury from the blast furnaces that make taconite is more difficult. Mercury is contained in the mined rock and produced when the iron ore is processed into taconite. But every furnace is a little different, he said, and the amount of mercury in rock varies across the Iron Range.

Even with these efforts, there is only so much the state can do. Only a tenth of the mercury that lands in Minnesota is produced by its industries. The vast majority comes from coal plants around the world, which emit it into the atmosphere. It eventually comes back down to earth with rain, and into wetlands, lakes and streams.

Xcel Energy, the state’s largest electric utility, currently is spending $50 million on two older coal units at its giant Sherco power plant in Becker, Minn. Minnesota Power, which supplies electricity to the Iron Range, plans to spend $350 million on the largest coal unit at the Boswell power plant in Cohasset, Minn. Both projects will reduce mercury and other emissions.

Otter Tail Power Co. is spending $10 million to cut mercury at two smaller coal-burning units near Fergus Falls by early 2015 so they can run another five years. After that, the utility plans to replace them.

$491 million project

Mercury reduction is one goal of a $491 million pollution-control project soon to begin at the coal-burning Big Stone power plant in Milbank, S.D. Otter Tail Power, the plant’s majority owner, says much of the expense is to control other emissions, including those linked to haze over the Boundary Waters Canoe Area Wilderness. Mercury controls are $2.1 million of the total cost.

Those wave of retirements and upgrades are on top of the earlier investments by utilities under the 2006 state mercury-reduction law.

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