“For us, it just came down to the fact that we don’t want to be operating on fossil fuels,” said company CEO Fred Thiel.

Marathon Digital, for example, currently has about 37,000 miners, but hopes to have 199,000 online by early next year, the company said.

Anne Hedges with the Montana Environmental Information Center said that before Marathon Digital showed up, environmental groups had expected the coal-fired power plant in Hardin, Montana, to close.

“It was a death watch,” Hedges said. “We were getting their quarterly reports. We were looking at how much they were operating. We were seeing it continue to decline year after year — and last year that totally changed. It would have gone out of existence but for bitcoin.”

Some companies in the industry acknowledge there is a problem and are committing to achieving net-zero emissions — adding no greenhouse gases to the atmosphere — from the electricity they use by 2030 by signing onto a Crypto Climate Accord, modeled after the Paris Climate Agreement.

Marathon Digital is one of several companies pinning its hopes on tapping into excess renewable energy from solar and wind farms in Texas.

Companies argue that cryptocurrency mining can provide an economic incentive to build more renewable energy projects and help stabilize power grids. Miners give renewable energy generators a guaranteed customer, making it easier for the projects to get financing and generate power at their full capacity.

The mining companies are able to contract for lower-priced energy because “all the energy they use can be shut off and given back to the grid at a moment’s notice,” said Thiel.

As Marathon Digital gradually moves its 30,000 miners out of Montana, it’s leaving behind tens of millions of dollars in mining infrastructure behind.

Just because Marathon doesn’t want to use coal-fired power anymore doesn’t mean there won’t be another bitcoin miner to take its place. Thiel said he assumes the power plant owners will find a company to do just that.