Just outside the northern French town of Avion, there’s a 20-foot-wide concrete disk with a small plaque reading “Shaft 7B 1920-1986.” The site marks the entrance to a coal mine that once employed 3,000 people, whose modest red-brick homes still stand nearby. These days, few signs of their work remain other than the 50-foot-high piles of tailings from the mine—and a pair of 12-inch-wide pipes protruding from the disk that connect to a tangle of tubes and valves.
The pipes carry methane, an odorless, flammable gas that gets released when the coal is dug out of the earth. Methane—the main component in natural gas—rises from 4,000 feet below and accumulates beneath the concrete plug, where a company called Française de l’Energie (FDE) captures it to produce heat and electricity. “You don’t need any underground installation,” says Julian Moulin, the company’s founder, touring the site in a reflective orange puffer over his blue blazer. “You just safely seal the former well-head, connect it to the pipeline, filter the gas, and inject it into the network.”