Reclaimed mine land and a surface coal mine sit adjacent to the Dry Fork Station, a 385-megawatt coal-fired power plant near Gillette, Wyoming. Credit: Mark Olalde / Energy News Network

At a recent mining conference, renewable energy emerged as a possible solution when reclamation funds are insufficient.

As U.S. coal consumption continues to decline, there’s slowly growing acceptance that more mine closures are inevitable and that the system meant to help clean up and repurpose the sites is underfunded.

One ray of hope for reclaiming the sites: renewable energy.

Patrick Molloy, an associate at Rocky Mountain Institute’s Sunshine for Mines program, said there has been more talk than action in covering disused mine waste piles with solar arrays or other forms of renewable energy generation. He said only two such sites are currently operating in the U.S.

“There is an untapped opportunity that can be developed,” Molloy said. “You give an opportunity for local communities to see a road past closure.”

The Rocky Mountain Institute published a report last year analyzing the potential to convert abandoned mine sites to renewable energy hubs. It found that using contaminated mined land for electricity generation could “transform these liabilities into revenue-generating assets.”

The idea was among those circulated at a mine closure summit hosted Nov. 7 by the Colorado School of Mines, the third such conference organized by the university since 2016.

Molloy said that innovative approaches to cleaning up mined land could take advantage of decreasing renewable energy costs. China, for example, opened a massive floating solar project last year on a lake that formed on old mine workings.

“Use the market — and it’s incredibly competitive right now — to find the right solution,” Molloy said.

Priscilla Nelson, head of the Department of Mining Engineering at the Colorado School of Mines, helped organize the conference. She said that while many examples of innovative post-closure uses came from metals mines, the coal industry holds significant potential because solutions do not need to be as site-specific.

Reclaiming coal mines comes with a “far more consistent set of problems,” Nelson said. “There’s a lot of variety in what needs to be handled in [metals mine] closure or during repurposing. Whereas in coal — coal is coal.”

Related: Mine cleanup funds at risk as coal power suppliers lose customers

Until recently, mined lands weren’t an attractive prospect for investors and developers. Molloy said that’s beginning to shift in the renewable sector.

“Solar developers have come on board as well with the view of developing commercial-scale solar,” Molloy said.

The conference came a day after several ballot initiatives aimed at better controlling pollution from mines in the West were soundly defeated. In Montana, measure I-186 would’ve halted the permitting of mines that anticipated perpetual water pollution, and Alaska’s Ballot Measure 1 would’ve added new permitting requirements for mines and other infrastructure impacting streams. Both measures failed after proponents were massively outspent by industry.

David Bieber manages reclamation plans at Western mines owned by Martin Marietta, an industry giant in the production of construction materials. Mine managers often push back against the implementation of closure plans, he said.

Companies traditionally treat a mine site “like an old plastic bag. You throw it away like it has no value,” Bieber said. When he can demonstrate how a developer could provide direction post-closure while not impacting the company’s bottom line, though, then “all of a sudden their attitude changes immensely.”