A polluting, coal-fired power plant found the key to solving America’s biggest clean energy challenge

The polluting coal plant is on its way out, scheduled for retirement in the next five years. It’s generated billions of dollars’ worth of electricity in its 50-year life, but the most valuable of its parts is the plug — how it connects to the grid that powers our homes.

Instead of letting it go to waste as the fossil fuel plant closes, Xcel Energy is going to leave it plugged in to connect the largest solar project in the Upper Midwest, and one of the largest in the entire country, directly to the grid.

Repurposing the so-called interconnection system is short-circuiting what could have been seven years of bureaucracy and red tape to get this electricity distributed to its customers.

Experts say this is the secret to solving America’s clean energy dilemma: There is more electricity from clean energy waiting to get connected to the grid than the entire amount of energy currently on the grid. The years-long delays are an existential threat to many projects’ chances of getting built.

A view of Sherco power plant, which has been operating since the 1970s and is slated for full retirement by 2030. Julian Quinones, CNN

Xcel Energy's Ryan Long explains how the company is leap-frogging the system to transition from coal to solar. Evelio Contreras/CNN

“It allows us to move much more quickly,” said Ryan Long, Xcel Energy’s Minnesota president, who called reusing the plant’s infrastructure “a real key to our strategy here.”

The US could essentially double the capacity of its electrical grid overnight by plugging renewables projects into old fossil fuel power plants, University of California Berkeley researchers found, whether they be coal, gas or oil. And projects could be plugged into existing plants, not just ones that are retiring.

“This should be one of the main strategies that we adopt going forward, because we already have so many existing assets, so much grid infrastructure and we don’t want to just throw them away,” said Umed Paliwal, a senior scientist at UC Berkeley and a lead author of the study.

It is far faster to build a project like Sherco solar right now than it is for that project to connect to the electric grid. That’s because room needs to be made on the grid to add new sources of energy, which requires lengthy engineering studies and uncertain project timelines. A cheap, clean energy boom is now running up against this complex, regional bureaucracy.

Rob Gramlich, CEO of consulting firm Grid Strategies LLC, likens plugging renewable projects into existing interconnection sites to using a fast pass to skip the long lines at Disney.

“There’s a line everybody wants to get on, and then somebody just has this Disney pass to skip the line,” Gramlich said. “It’s a sensitive topic to talk about, jumping around the interconnection queue. But the reality is, it’s there.”

From super-polluters to clean energy juggernauts

The answer to supercharging clean energy could lie inside some of the most polluting power plants in the US.

Sherco has been Minnesota’s largest coal-fired power plant — and its biggest polluter — since it was built over the course of the 1970s and 80s. Its smokestacks emitted around 10.5 million tons of planet-warming pollution in 2022 alone, the equivalent of over 2 million cars spewing emissions in a year.

CNN's Bill Weir looks at the coal fire that generates energy for thousands of customers through a protective welder's mask. Julian Quinones, CNN

Outside the plant, solar panels span acres of farmland. Sherco — a fossil fuel behemoth — looks small in comparison. 

Julian Quinones, CNN

But as Berkeley researchers found, plants like Sherco that are either gradually retiring or even still operating are good candidates for renewables to plug into their infrastructure.

“Any fossil fuel power plant does not operate every single hour of the day,” said Sonia Aggarwal, CEO of clean energy think tank Energy Innovation, and a former White House climate official. “The other hours — that big plug, this really valuable resource that everyone is waiting years to get access to — that’s just sitting there, not being used.”

Aggarwal and Paliwal argue this method allows utilities to have the best of both worlds; they can build wind and solar farms nearby, put that clean energy on the grid during the hours a coal or gas plant isn’t producing electricity, and not have to entirely shut down a plant.

Doing so brings a multitude of benefits. It helps save jobs at a plant that might otherwise be threatened by closure and helps increase the local tax base around the plants. In Minnesota, Xcel is promising no layoffs for workers at the Sherco coal plant.

“We really need them to stay at those coal plants until the end of (the plant’s) life because they do provide critical reliability and energy for our communities,” Long said. “When the time is right, we’ll find them a job at Xcel Energy and we’ll retrain them and position them for success in that role.”

It can also result in savings for electric customers, as the plants ramp down coal and switch to wind and solar, which are far cheaper sources of energy.

The Berkeley study considered several factors to determine good candidates for interconnection: whether there was land nearby a thermal plant suitable for wind and solar; how much energy could be generated by the sun or wind; and how much renewable energy could be fed into a plant’s interconnection system.

The answer to that last question? A lot.

Paliwal and his colleagues found that by 2032, utilities could install a whopping 1,000 gigawatts of new clean energy near power plants that checked all three boxes. And those are the big numbers America needs; energy analysts believe data centers, AI and the increased demand as people electrify homes and cars.

Several power plants in Illinois are attempting something similar, and in Virginia, a new solar array is plugging into the interconnection at a nearby gas plant.

Solar panels sit on acres of old farmland in Becker, Minnesota — part of Xcel Energy's massive Sherco solar project. Julian Quinones, CNN

For Pete Wyckoff, who serves as the Minnesota Commerce Department’s deputy commissioner of energy resources, the Sherco solar farm represents a chance to produce energy locally.

“We’re a good wind and solar state,” Wyckoff said. “Anything we burn that’s fossil fuel, we are importing. We are making the wind and solar electricity here.”

It’s also a huge step forward for Minnesota’s climate and clean energy goals. Under its Democratic governor and 2024 vice-presidential candidate Tim Walz, the state is aggressively trying to decarbonize its power sector — getting to 100% clean electricity by 2040.

“That is a key driver for how we’re going to decarbonize the rest of the economy,” Wykoff said. “We’re aiming to be clean economy-wide by 2050. And I think we can get there.”