U.S. oil and gas drilling and related operations give off much more of the powerful greenhouse gas methane than the federal government estimates, wasting about $20 billion in fuel a year, scientists said on Thursday.

Methane, the main component of natural gas, is colorless and odorless. It is a major force in short-term global warming because it has more than 80 times the warming potential of carbon dioxide in the first 20 years after it escapes into the atmosphere. In high concentrations it can also lead to formations of smog, which is linked to heart and lung damage.

The amount of methane leaked from U.S. oil and gas wells and related infrastructure in 2015 equaled about 2.3 percent of the country's overall natural gas output, a study led by the Environmental Defense Fund advocacy group said. That was much more than the 1.4 percent the Environmental Protection Agency estimated for 2015 in a report last year.