Bitcoin miners revived a dying coal plant - then CO2 emissions soared

Environmentalists in Montana called it the "death watch". Following years of financial losses one of the handful of remaining coal-fired power plants in the state appeared doomed, its likely fate offering a small but noteworthy victory in the effort to avoid disastrous climate change. But then a bitcoin mining company stepped in to resurrect it.

The Hardin generating station, a 115-megawatt coal plant located a dozen miles from the historic site of the famous battle of Little Big Horn in southern Montana, was slated for closure in 2018 due to a lack of customers only to somehow limp on, operating on just 46 days in 2020. "We were just waiting for this thing to die," said Anne Hedges, co-director of the Montana Environmental Information Center. "They were struggling and looking to close. It was on the brink. And then this cryptocurrency company came along."

In a deal struck in late 2020, Marathon, a bitcoin "mining" company, became the sole recipient of the power station's electricity. It established an elongated data center on 20 acres of land beside the facility that is packed with more than 30,000 Antminer S19 units, a specialized computer that mines for bitcoin. Such thirst for power is common in crypto - globally bitcoin mining consumes more electricity than Norway, a country of 5.3 million people.

As the bitcoin miners moved in last year, Hardin roared back to life. In the first nine months of 2021 alone, the plant's boilers fired up on 236 separate days. Planet-heating emissions from the burning of Hardin's coal soared too, with 187,000 tons of carbon dioxide emitted in the second quarter of last year, more than 5000% more than was expelled in the same period in 2020.

In the third quarter, a further 206,000 tons of CO2 was emitted, a 905% increase on 2020, Environmental Protection Agency (EPA) data shows. Hardin was operating at "near full capacity", Marathon said in a December update, with the data center producing around 34 bitcoin on 1 December.

"I was horrified to see it all happen, it was a terrible turn of events," said Hedges, who took to visiting the plant and photographing the new data center as it took shape, fans perched on its roof to help cool the humming computer hardware. "This isn't helping old ladies from freezing to death, it's to enrich a few people while destroying our climate for all of us. If you're concerned about climate change you should have nothing to do with cryptocurrency, it's a disaster for the climate."

Hardin is part of a wave of America's "zombie" fossil fuel plants that have been brought back from the dead by cryptocurrency companies looking to feed the insatiable energy demands of their mining operations. China, formerly the epicenter of the bitcoin industry, effectively banished around half of the world's currency miners last year and the resulting search for cheap power has seen companies eye struggling US power stations.