Building on brownfields: A first-in-the-US storage project lands on a coal site

Today, the Columbia Energy Center in Pardeeville, Wisconsin, looks much like any coal plant: smokestacks billowing into the air and nondescript buildings, all surrounded by chain-link fencing. 

But in a matter of years, a huge, oblong dome is expected to be plopped onto 12 acres of the site. Inside, the dome will house a pioneering long-duration energy storage technology, the first of its kind planned in the U.S.

The Midwestern utility Alliant Energy owns the property, and will be one of the first to install this type of storage project, which is designed by an Italian company called Energy Dome and relies on compressed carbon dioxide. Once completed, the 20-megawatt project will have the capacity to power about 20,000 homes. If it's successful, the utility is interested in adding even more domes, potentially up to a dozen, after the site’s life as a coal facility ends in 2026.

Reusing sites like these for clean energy projects is not a new concept — indeed, industry observers have been encouraging the placement of renewable projects on brownfields for over a decade — but their use for long-duration storage projects, especially by the same utility that already owns the property, is a relatively new variation on the theme. Alliant’s reasons for building the project on the site of its own coal plant embody some of the advantages of the practice, which remains niche even after years of enthusiasm from state and federal government. 

There are indications that building on brownfields could become more common, however, especially as fossil fuel plants continue to retire and the benefits — including all-important access to transmission — are increasingly attractive. Illinois has recently provided funding to transform five old coal sites into solar facilities, and Alliant itself has built a solar project on an old coal ash landfill. In Wyoming, Bill Gates-backed TerraPower is developing a nuclear project near the location of an old coal plant.

Building clean energy and climate tech projects on brownfields is “happening a lot more, I think, than anybody really realizes,” said Gail Mosey, a senior researcher in land reuse at the National Renewable Energy Lab. “In many cases, it's the best reuse of land.”

Today, though, these cases of transformation still represent a tiny sliver of the country’s total brownfields sites, which now number more than 450,000. Only about 500 renewable energy projects have been built on those sites, according to data from the Environmental Protection Agency. 

It remains an open question when, and if, climatetech developers will fully embrace building on these sites, but there is certainly a potential synergy between the large number of them and the significant capacity that needs to be added to the grid, especially storage capacity. A grid built for net-zero emissions will need between 225 and 460 gigawatts of long-duration energy storage by 2050 alone, according to a recent Department of Energy report.

Building on brownfields can be easier for a developer for a number of reasons, said experts like Mosey. Perhaps highest on that list is the potential to avoid long interconnection lines, a notorious project killer. In 2023, the U.S. interconnection backlog exceeded 2 terawatts, a figure likely to intimidate any developer. Many previous site uses, like manufacturing or electricity production using fossil fuels, required a connection that can be reused. In Wisconsin, that’s a key consideration for Alliant. 

“One of our objectives is to try to retain the interconnect capacity opportunities that we have at those retiring plants,” said Mike Bremel, the company’s director of engineering and customer solutions. 

Though Alliant’s coal plant is slated for decommissioning in the same year that the dome is projected to be constructed, there’s incremental capacity left on the grid that the utility can tap into. Finding a new location for the storage project would have required Alliant to put it at the end of a long queue. (MISO has more than 120 Wisconsin projects currently in line).

Cheap land is also good for clean energy projects, because that cost gets factored into the overall levelized cost of electricity. Certain sites may need remediation, but previously used land can be cheaper than greenfields, said Soji Adelaja, a professor of land policy at Michigan State University. Cleaning up those sites could also help a project move forward in the regulatory process, by creating societal benefits that decision makers may recognize. 

“The fact of the matter is, we just don't have enough money to clean up all the sites across the country,” said Adelaja. “By going from some of the more toxic and environmentally-degrading uses of land to some of the more promising and green and renewable uses of land, that’s just a major, major, major gain for society.”

Governments and community members may be eager for an abandoned site to be put to new use, said Mosey. In fact, renewables projects on undeveloped land have at times faced pushback from environmental groups and community groups, who say it would be better to build on already disturbed sites. 

In certain circumstances, redevelopment can even mean financial incentives. The EPA, for instance, provides a variety of grants for development on brownfields and has created a map specifically focused on brownfields that could be redeveloped for renewable energy, though currently it only estimates potential for wind, solar, geothermal, and biomass projects, but not storage. 

Alliant received a Department of Energy demonstration grant to build its long-duration energy storage project. The Inflation Reduction Act also includes tax credits for projects in “energy communities,” which include areas with brownfields or closed coal mines.

With all this upside, it may seem odd that more of those projects haven’t been completed. There are more than 3,600 solar projects larger than 1 megawatt across the U.S., according to a U.S. Geological Survey database; EPA data suggests only 465 of those are on brownfields. 

But there are also hurdles when picking a used site. Community engagement, for instance, can present a challenge for building on brownfields, because projects still require local consultation and buy-in.