On hot summer days, as air conditioners blast across the Upper Midwest, Xcel Energy's Sherburne County Generating Station gulps 320 train carloads of low-sulfur Wyoming coal. Every day.

The energy released from burning that coal heats water streaming through hundreds of miles of boiler pipes to more than 1,000 degrees. The steam spins generators that can make enough electricity to power nearly 2 million homes.

The Sherburne station, known as Sherco, generates lots of power and economic muscle across the region. But its coal furnaces are also the state's single largest source of carbon emissions, pumping out 20 million tons of CO2 every year from its stacks, according to the federal Environmental Protection Agency.

Those emissions have put those furnaces at the center of a debate over climate change and economic growth. New federal regulations targeted at climate change call for power plants to slash power plant CO2 emissions 32 percent by 2030. That's raised fears that Sherco's two older units could be shuttered and ignited a debate over whether Minnesota leaders should fight the federal plan.

"If you look at the carbon dioxide issue, the real problem is China, India, Nigeria. Minnesota is just a speck on the map in terms of carbon dioxide emissions," state Rep. Pat Garofalo, R-Farmington, said Monday during a legislative hearing on Sherco, the largest coal fired operation in Minnesota.

During peak load times, Sherco's three furnaces consume as much as 320 rail car loads of coal per day. The coal is stored outside the plant. Matt Sepic | MPR News

Shutting those furnaces, he said, would deliver the state a major economic hit, said Garofalo, who chairs the Minnesota House Job Growth & Energy Affordability Policy and Finance Committee. "In Minnesota we're already reducing our carbon emissions. The cost-benefit ratio is really out of whack."

State Rep. Melissa Hortman, DFL-Brooklyn Park, countered that even if two of the three Sherco units are eventually shut down, employees there could find work in the renewable energy sector.

"We can't ignore the fact that there's a cost to keeping old coal plants operating into the future," Hortman said. "There will be jobs in wind and solar to offset the job losses in the coal industry."

The "clean jobs" promise has its skeptics.

Kurt Zimmerman, 47, a business representative for the International Brotherhood of Electrical Workers, said Monday night that employees he sees at the union hall are worried about their future

The coal-fired power plant provides hundreds of steady jobs with good pay and benefits, he said, adding that while wind turbine and solar power projects may provide short-term construction jobs, they may not bring multi-decade careers.

"You can build the turbines," said Zimmerman, who worked 25 years at Sherco. "But once they're up and functioning, you don't need a mass amount of people to run those, where we do here."

Smokestacks at Sherburne station are as tall as skyscrapers. Matt Sepic | MPR News

Others at the hearing spoke in favor of the federal carbon cuts.

Barbara Commers of Clear Lake Township, Minn., said the U.S. — and Minnesota — should lead the way in cutting carbon emissions.

"Billions of lives, and incalculable suffering is at stake. We need to take action now," Commers told the hearing. "There is very little time left for our children and our grandchildren."

Sherco does have pollution control "scrubbers" that filter out nitrogen oxide, sulfur dioxide and soot. Most of what the public sees pouring from the Sherco stacks is water vapor, not smoke or combustion products, according to plant manager Ron Brevig. But they can't answer the CO2 question.

Xcel Energy officials say they're still figuring out what the EPA's new carbon emissions rules will mean for Sherco. The company is expected to provide more details to state regulators when it files an update to its resource plan late next week.