Nearly two years after a failure of one of its units led to extensive damage, Xcel Energy's Sherburne County Generating Station is back to normal.
Xcel Energy officials spent more than $200 million to fix Unit 3 at Sherco, the state's largest coal-fired power plant. Xcel officials say insurance will cover most of the cost of repairs.
The successful repair at the facility, located about 45 miles northwest of the Twin Cities, comes as Xcel and state regulators discuss the future of the other two units, which environmentalists say should be retired.
On Nov. 19, 2011, corrosion led to extensive cracking in a row of turbine blades, causing the massive failure at Unit 3. After extinguishing fires, Xcel called in experts to assess the unprecedented damage.
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"We had never experienced a failure like this in our past and we really had no roadmap to follow," Sherco Plant Director Ron Brevig said.
It soon became clear, he said, that it would take a long time to return the unit to service.
"We found that the extent of the repair required was much more than we originally thought," Brevig said. "So that was a very significant thing we learned as we disassembled the machine and then the extent of the repairs and how sophisticated the repair technologies and methods had to be to get the machine restored and back operating."
Since the repairs were completed a couple of weeks ago, Xcel has operated the unit as officials performed a variety of tests.
Brevig said the unit passed.
"It's operating very, very well at this point in time," he said. "We're very encouraged from the results of all the testing that we did after the restoration. It's got many, many years of reliable operation left."
That's good news for Xcel Energy. Sherco's three coal-fired units supply about 2,400 megawatts of electricity — enough to serve more than 2 million homes and businesses.
The plant in Becker, Minn., also employs about 350 people. Becker City Administrator Greg Pruszinske said 77 percent of the city's budget this year comes from taxes paid by Xcel. The city is watching closely as state regulators and Xcel officials discuss the future of Units 1 and 2 — older and dirtier units than the restored Unit 3. Besides pollutants like sulfur dioxide and mercury, coal plants emit carbon dioxide, a greenhouse gas linked to climate change.
The federal government is moving toward making power plants pay for their emissions, and environmentalists and clean energy advocates want Xcel to retire Sherco's older units, which were built in the mid-'70s. Thousands of people have weighed in by submitting comments to the state Public Utilities Commission.
Pruszinske said city officials want Sherco to keep operating.
"We think they have done a good job of making sure that those plants are as efficient as possible," he said "We think they've done a good job making sure they're burning as cleanly as possible. We think shutting Sherco 1 and 2 down immediately is a mistake just from a regional standpoint as far as cost of power and we think that ratepayers will see a substantial increase if it's closed."
The vast majority of the more than 8,000 comments filed in the case urge retirement of the units, including a handwritten letter from Dick Ottman of White Bear Lake. He wasn't impressed by the news that Minnesota's largest coal plant was back at full capacity.
"Obviously that's nothing to celebrate," said Ottman, a retired engineer.
Ottman hopes the state will force Xcel to make some decisions about replacing coal with wind and solar.
"You just need a lot of very practical people and you get some good minds, you get them in the room and you start laying out the various alternatives and you can come up with very creative solutions," he said. "And the technology is all there. You don't have to reinvent anything."
Xcel officials have said they want to continue using Sherco until more is known about the future costs of operating coal-fired power plants.
But Kevin Reuther, legal director of the Minnesota Center for Environmental Advocacy, said even Xcel's own study of what to do with Sherco 1 and 2 gives reason to move toward retirement. Reuther said the outage at Sherco 3 showed Minnesota can live on less coal.
"We can get along without these big behemoth plants. We've been doing it for two years now. The lights have remained on," he said. "This is like an experiment that nobody asked for but pretty much proves that we don't need these big plants on line."