Stronghold Digital Mining, a new, “ESG-friendly” bitcoin-mining firm, uses the electricity from the Scrubgrass Generating Plant in Kennerdell, Pennsylvania, to power its operations.
Scrubgrass burns not coal but waste coal—the stuff left over from coal mining, also called “culm” or “tailings.” At least 450 million tons of waste coal sits around in western Pennsylvania; acid runoff from these piles contaminates the land and turns streams red with iron oxides, and the piles themselves are liable to catch fire.
This works out to around 1.67 tons of carbon dioxide emitted per megawatt-hour of power—far more than the US average for regular coal, which is 1.1 tons of carbon dioxide per megawatt-hour.
During the Obama administration, more rigorous emissions standards were imposed on coal-waste power plants, to curb the levels of metals like mercury, acid gases like hydrogen fluoride, and particulate matter spewed out of these plants.
The environmental slogan for coal—”Leave it in the ground”—may not apply to waste coal, which does a lot of damage sitting around in piles of refuse and therefore needs to be cleaned up.