The United Nations Intergovernmental Panel on Climate Change has determined that one pound of sulfur hexafluoride, an electrical insulator, heats the planet as much as 25,200 pounds of carbon dioxide and remains in the atmosphere for 3,200 years. The U.S. Environmental Protection Agency (EPA) has labeled it as one of several long-lived, synthetic, fluorine-containing chemicals released by heavy industry, chemical manufacturers, semiconductor manufacturers and electric utilities, noting that once released, they are “essentially, permanent additions to the atmosphere.”

Duke Energy reported leaking nearly 11 metric tons of it into the atmosphere from its electric substations in North and South Carolina in 2020, according to mandatory EPA reporting. Their greenhouse gas equivalency calculator states those emissions amount to the annual greenhouse gas emissions of more than 59,000 automobiles.

The 88 utilities that participate in the EPA emissions reduction program, nearly half of the U.S. electric grid, are looking for ways to completely eliminate sulfur hexafluoride emissions. Unless they succeed, emissions will likely increase along with growth of the electric grid, which must increase to two to five times its current level by midcentury if the country is to meet its net-zero emissions targets.