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

The chimneys of the old Sherco coal-fired power station tower above the gleaming solar panels that stretch across thousands of hectares of farmland.

The polluting coal plant is on its way out, scheduled to close within the next five years. The plant has generated billions of dollars of electricity over its 50-year life, but its most valuable component is the plug — how it connects to the grid that powers our homes.

Rather than let it go to waste as the fossil fuel plant closes, Xcel Energy is leaving it connected to create the largest solar project in the Midwest and one of the largest in the entire country directly connected to the grid.

By redesigning the so-called interconnection system, an end is put to the bureaucracy and administrative hassle that was necessary to get electricity to customers.

According to experts, this is the secret to solving America’s clean energy dilemma: There is more clean energy electricity waiting to be connected to the grid than the total amount of energy currently on the grid. The years-long delays pose an existential threat to the chances of many projects getting built.

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

The U.S. could essentially double the capacity of its electric grid overnight by plugging renewable energy projects into old fossil fuel plants, whether they’re coal, gas or oil, researchers at the University of California Berkeley have found. And the projects could be plugged into existing plants, not just ones that are retiring.

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

It is now much faster to build a project like Sherco Solar than to connect it to the grid. That’s because space must be made on the grid to add new energy sources, 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, compares connecting renewable energy projects to existing interconnection sites to using a fast pass to skip the long lines at Disney.

“There’s a line that everyone wants to be in, and then someone just has a Disney pass to skip the line,” Gramlich said. “It’s a touchy subject to talk about, skipping the line for the interconnection. But the reality is that it’s there.”

From super polluters to clean energy giants

The solution to boosting clean energy may lie in some of the most polluting power plants in the US.

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

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

“A fossil fuel plant doesn’t run every hour of the day,” said Sonia Aggarwal, CEO of the 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 waits years to get access to — it just sits there, unused.”

Aggarwal and Paliwal argue that this approach allows utilities to get the best of both worlds: They can build wind and solar farms nearby and feed the clean energy into the grid during the hours when a coal or gas plant isn’t producing electricity. And they don’t have to shut down the plant altogether.

This has a multitude of benefits. It helps save jobs at a plant that would otherwise be at risk of closure, and it helps expand the local tax base around the plants. In Minnesota, Xcel has promised no layoffs for workers at the Sherco coal plant.

“We really need them to stay with those coal plants until the end of their life because they 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 could also lead to savings for electricity customers as plants phase out coal and switch to wind and solar power, which are much cheaper energy sources.

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

The answer to that last question? A lot.

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

Several power plants in Illinois are trying to do something similar, and in Virginia, a new solar array is being connected to a nearby gas plant’s grid.

For Pete Wyckoff, deputy commissioner for energy resources at the Minnesota Commerce Department, the Sherco solar farm is an opportunity to produce energy locally.

“We’re a good wind and solar state,” Wyckoff said. “Everything we burn that’s fossil fuel, we import. We make wind and solar 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 — aiming for 100% clean electricity by 2040.

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

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