Natural gas is being touted as the climate-friendlier fuel that the United States can use to wean itself off coal, which releases twice the amount of carbon dioxide as natural gas when burned. But the surge of cheap natural gas may not do much to reduce long-term U.S. emissions of carbon dioxide, a new study suggests, because it could delay the deployment of cleaner renewable energy sources such as solar and wind.
"If you have lots of cheap natural gas available, ultimately it's not fighting only against coal but renewables, too," says Steven Davis, an energy scientist at the University of California, Irvine, and co-author of the study, published online today in Environmental Research Letters.
For their analysis, the authors developed scenarios of what the future mix of energy sources might look like in the United States, based on factors including cost and technology availability. In part, they drew on forecasts of future U.S. natural gas supplies developed by 23 experts in academia, industry, and finance; the forecasts ran the gamut from bullish to bearish. The researchers next ran those numbers through an optimization model that produced a likely energy mix.
The results suggest that abundant natural gas will make little difference in lowering U.S. greenhouse gas emissions through 2055, because it will compete with and displace renewable energy sources. (This held true even if no methane were to escape from the natural gas infrastructure, an important issue because methane is a warming gas that is 120 times as potent as carbon dioxide.)
"This is straightforward analysis that quantitatively shows what many have been very concerned about—that abundant natural gas will tend to suppress renewables," says Andrew Rosenberg, director of the Center for Science and Democracy at the Union of Concerned Scientists in Cambridge, Massachusetts, who was not involved in the study.
That may be true in the long run, but natural gas does appear to be helping the United States reduce emissions today, points out John Quigley, an alternative energy consultant in Harrisburg and former secretary of Pennsylvania's Department of Conservation and Natural Resources, who was not involved in the study. By 2035, the Energy Information Administration (EIA) estimates that electricity generation from coal-fired power plants will drop to 34% of the U.S. energy mix (from 39% in 2013 and 52% in 2000), mostly due to cheap natural gas and retiring coal plants. And although solar is currently booming in the United States, EIA estimates renewables will cumulatively make up only 16% of electricity generation in 2040.
Changes in U.S. climate policy—and not just in the supply and cost of fuels—will play a big role in accelerating or slowing shifts in the U.S. energy mix, Quigley and the authors agree. "Policy is everything,” Quigley says. "We need strong limits on emissions and policies that encourage renewables. We have to have comprehensive climate and energy policy that takes advantage of the resources that we have in this country."