Carbon emissions from burning natural gas are projected to surpass emissions from coal by around 10 percent this year.
It will be the first time that's happened since 1972, according to data from the U.S. Energy Information Administration. Although natural gas emits nearly half as much CO2 as coal when burned for electricity, consumers are using more and more of it. In the first four months of this year, the U.S. consumed more than twice as much energy from natural gas as from coal.
Ian Lange is a professor of Economics at the Colorado School of Mines. He said changes in the mix of fuels people use are largely due to price.
"Oh, I mean it's all of it, right? Natural gas prices are very low. Renewables are coming down," Lange said.
The price of natural gas is around two-thirds of what it was in 2014.