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Minnesota Power coal plant upgrade stimulates Iron Range economy

In tough economic times, a $240 million upgrade and retrofit of Minnesota Power's Boswell Energy Center in Cohasset has provided a welcome supply of construction jobs in the Northland.

New turbine
A new steam turbine costing $13 million will be installed in the refurbished Unit 3 of the Boswell Energy Center in Cohasset, boosting efficiency. (Bob King / rking@duluthnews.com)

In tough economic times, a $240 million upgrade and retrofit of Minnesota Power's Boswell Energy Center in Cohasset has provided a welcome supply of construction jobs in the Northland.

The massive project -- which includes eight stories of scaffolding inside a huge boiler -- employs as many as 600 day-shift tradespeople and more than 200 on the night side.

That's kept hundreds of workers from riding the bench at Northland union halls, said John Grahek, a business agent for the Iron Range Plumbers and Pipefitters Union and president of the Iron Range Building Trades Association.

"Minnesota Power has been our stimulus package up here," he said.

Workers are engaged in a big final push -- many logging six 10-hour shifts per week -- to make a 2½-month deadline on the retrofit that's intended to bring the facility's emissions in line with those of a state-of-the-art coal plant. Expectations are for mercury emissions to be reduced by 90 percent, nitrogen oxides by 81 percent, sulfur dioxide by 90 percent and its particulate matter by 93 percent, said Al Rudeck Jr., Minnesota Power's vice president of generation.

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To get the work done, Minnesota Power idled its coal-burning behemoth, dubbed Boswell Unit 3, at 10:43 p.m. Aug. 14, with hopes of restarting it in

80 days. It's the first time the generator, the company's second largest, has been taken down for any considerable duration since its construction in 1973.

With the capacity to produce 350 megawatts of power -- enough juice to meet all of Duluth's residential and commercial needs four times over -- it's a key piece of equipment, Rudeck said, which is why there's such a rush to return it to service. He noted a reduced call for power with the downturn in taconite mining this year has given the utility a bit more breathing room than usual to accomplish the retrofit.

Although Minnesota Power has said it has no plans to develop more coal-fueled power generation, Rudeck said low-cost coal continues to play a key role in the company's business.

"We have one of the highest load factors of any utility in the country," he said. "And many of our largest customers require copious amounts of low-cost electricity."

Even so, Boswell and other coal-burning plants continue to draw the concern of conservation groups.

"Any facility that's going to continue to emit particulate matter, sulfur dioxide, nitrogen oxides and carbon dioxide is part of the problem," said Stephanie Kodish, clean air attorney for the National Parks Conservation Association.

Kodish's organization this week joined a formal request for Minnesota to change its haze-reduction plan, requiring plants to update pollution controls and curb air emissions to better protect public lands and area residents.

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Rudeck says Minnesota Power has been making progress. He noted that, while the Boswell Unit 3 project is the largest undertaking to date, it will be the eighth retrofit of a coal-burning facility completed in the past three years, and all have significantly reduced emissions.

Josh Skelton, the facility's operation's manager, said the upgrade should see the plant running smoothly for the next 30 years.

As part of that effort, eight stories of scaffolding were erected inside the unit's boiler, and workers sandblasted it, top to bottom, burning through 850,000 pounds of sand to remove ash build-up from its interior. Workers then inspected the nearly 300 miles of water tubes that line the interior walls of the boiler and mended the weak points.

Rudeck said Minnesota Power also is installing a new $13 million high-pressure turbine in the unit, to increase its output.

To help move the boiler's flue emissions through a catalytic converter, a wet scrubber and a baghouse, workers are installing two 13,000-horsepower fans. And even though the addition of some of these new emission controls will consume significant quantities of energy, efficiency gains will compensate for that, ensuring that there will be no loss of net output from Boswell 3, Rudeck said.

Most of the cost of improvements at Boswell already has been passed along to Minnesota Power's customers in the form of higher rates, but Rudeck said the utility still aims to recoup some of its investment through another rate increase, which it will seek next year. The size of that requested increase has yet to be determined.

Peter Passi covers city government for the Duluth News Tribune. He joined the paper in April 2000, initially as a business reporter but has worked a number of beats through the years.
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