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Xcel Energy’s race to retire coal plants and remove carbon emissions from the state’s power grid may rely on plans to keep Minnesota’s three aging nuclear reactors operating for decades.

That prospect has a number of environmental groups, some of which have protested the state’s nuclear policies in the past, wrestling with how to respond. In an era when greenhouse gases and climate change have become a more pressing environmental threat than nuclear waste, several groups want to take a closer look at the potential benefits of Minnesota’s nuclear reactors.

Some places such as Germany are actively trying to shutter their nuclear plants, and several states across the country are retiring them early in a search for cheaper energy. But here in Minnesota, nuclear power may be a linchpin in Xcel’s efforts to meet its promise to customers to make energy production carbon-free by 2050, said Chris Clark, Xcel’s president for Minnesota and the Dakotas.

“I think the places that allow nuclear to close are going to find it much harder to exit coal,” Clark said. “These plants are critical to helping achieve that carbon reduction.”

Nobody knows exactly what the future of wind and solar might be, but experts agree the technology isn’t there yet to rely on those resources alone. It’s far from certain that it ever will be. In that case, billion-­dollar decisions need to be made now on how to best cover the gap that wind and solar might never bridge.

When the priority is for Minnesota to phase out coal and stop construction of new natural gas plants, any carbon-free energy “takes on new value,” said Allen Gleckner, senior director of energy markets and regulatory affairs for Fresh Energy, a renewable power research and advocacy group.

The future of nuclear energy all comes down to cost and safety, said Steve Clemmer, director of energy research and analysis for the Union of Concerned Scientists, a global-warming control advocacy group that has long been skeptical about the economic viability of nuclear reactors.

The big fear is that hydraulic fracturing, or fracking, has made natural gas so cheap that when nuclear plants are retired early, the power they had supplied would be replaced by carbon-emitting gas plants rather than by wind or solar, Clemmer said.

“Natural gas is the wrong direction,” he said. “So if the reactors can be safely extended and it makes financial sense, then nuclear could absolutely play a significant role here in the next 15 years or beyond.”

Upgrades needed

Minnesota’s three reactors, one in Monticello and two in Prairie Island, have been providing about a fifth of the state’s power, or even more, for decades. They need extensive upgrades — in the range of $1.4 billion — to continue operating to the end of their permits in the early 2030s. With that kind of investment, Xcel plans to ask nuclear regulators to extend the life of at least one of the reactors until 2040.

Like the vast majority of the country’s 96 operating reactors, all three were built in the 1970s under 40-year operating permits. In the early 2000s, the Nuclear Regulatory Commission extended most of the permits 20 years into the 2030s.

Facing extensive repairs, and cheaper energy from wind, solar and natural gas, utilities across the country have been split on whether to retire their reactors early or make needed upgrades.

Since 2013, nine nuclear reactors have been shut down years before their permits were set to expire, including in Wisconsin and Pennsylvania, according to the U.S. Department of Energy. Several more would have been retired in Illinois and New York had state lawmakers not stepped in to subsidize their reactors to keep them open as carbon-free options.

Losing nuclear power is shortsighted, especially when that power is replaced by natural gas, Clark said.

“My fear is that when these nuclear plants close, they’re not necessarily getting replaced with carbon-free resources,” he said.

The costs to upgrade Minnesota’s reactors would be paid for by Xcel customers, who have already paid for significant upgrades to the reactors in the past decade. Repairs to the Monticello reactor finished in 2013 cost $748 million — more than double the original estimate.

If the proposal to extend the life of the Monticello plant moves forward, Clemmer said, regulators will need to watch out for that.

“It’s really important that we take a close look at exactly what is needed, what it will cost and make sure this would be able to operate safely for another 20 years,” Clemmer said.

By keeping the reactors around, the state has an option if technological advances don’t come as quickly as many hope, Clark said.

Xcel’s highly touted plan to be carbon-free by 2050 calls for cutting carbon emissions by 80% in just 10 years. But the utility said it would need another 20 years after that to cut the rest — and nobody is quite sure how to do that yet.

A 2018 study from researchers with the Harvard University Center for the Environment found that costs exponentially increase as more of the power grid relies on variable resources such as wind and solar. That’s because we don’t have the technology yet to store more than a few hours of energy.

To buy enough current batteries to store a week’s worth of energy produced in the U.S., the study found, would cost more than $7 trillion, which is roughly 19 years of total electricity expenses in the country.

Winter challenges

To get through the dark Minnesota winters, the power grid here would need to store days or weeks of energy.

Costs could come down if renewable technology keeps advancing at the pace it has over the past 20 years, Clark said.

“I won’t rule anything out,” Clark said. “But we can’t risk reliability or affordability.”

But there is still a question of how compatible nuclear power would be with a grid that relies much more on wind and solar than it does today. Nuclear power has never been a very flexible resource, with Minnesota’s reactors operating at close to full capacity every day of the week.

If the grid had a glut of energy on sunny and windy days and a dearth of energy on still winter nights, nuclear reactors would need to be able to ramp up or down as needed to avoid sunken costs and wasted energy. Xcel is researching ways to improve that flexibility, Clark said.

In 2018, the Union of Concerned Scientists ranked nuclear reactors across the country by how likely they were to close. Minnesota’s reactors were near the top of the list, largely because of the repairs needed and potential struggle to get them to profitability.

But when utilities start to factor in the cost of each ton of carbon put in the atmosphere and each ton saved, it doesn’t take long for older reactors to start to make more economic sense than new natural gas plants, Clemmer said. That’s a vital calculation to make now because more electric vehicles and more heating systems are being added to the power grid, he said.

“It’s going to require a lot of resources to come up with that higher demand,” Clemmer said.

Greg Stanley • 612-673-4882