According to Bloomberg, Arch Resources, the second-largest U.S. coal miner, has sold every lump of coal it will extract out of the ground for 2022. The company has sold next year's coal for 20% over the current spot. Peabody Energy Corp., the top U.S. coal miner, has sold 90% of all its coal from the Powder River Basin area for 2022. 

Arch's CEO Paul Lang said the company's thermal coal output for 2022 is "fully committed." According to S&P Global Market Intelligence, Arch sold the coal for $16 per ton, well over last week's $13.25 spot price. 

"It's pretty much sold out," Peabody CEO Jim Grech said Thursday during a conference call. "We only have a small portion left to be sold for 2022 and for 2023."

Alliance Resource Partners LP, a coal miner that will ship 32 million tons this year, has already locked in 2022 contracts to deliver 30 tons and 16 tons in 2023. 

"Our challenge in America is most producers are all sold out," Alliance CEO Joe Craft said last week.

Surging demand for coal ahead of the Northern Hemisphere winter comes as the global energy crunch has forced natural gas prices to record highs worldwide. Power plants are transitioning away from natgas generation because it's uneconomical at current prices, hence the increasing demand for the dirtiest fossil fuel.