Significantly increased production of natural gas in the United States has dramatically changed the country’s energy landscape—both lowering domestic natural gas prices and providing substantial economic benefits. At the same time, debate has surrounded the environmental impacts of natural gas as compared with other fossil fuels.
Specifically, given that natural gas contains less carbon than either coal or oil, it produces less carbon dioxide when burned, yielding substantial climate benefits. On the other hand, natural gas is composed largely of methane, a greenhouse gas (GHG) more potent than carbon dioxide; therefore, the overall emissions benefits of natural gas hinge critically on earlier stages in the natural gas lifecycle—production, transportation, and distribution—and specifically on the amount of methane that is released into the atmosphere without being combusted.
Prompted by these uncertainties and the need to better understand the climate impacts of increased natural gas production and use, researchers have been investigating natural gas emissions throughout its lifecycle. For example, the nonprofit Environmental Defense Fund—in concert with a large number of academic and industry partners—is conducting more than a dozen studies of its own, which cover natural gas production, gathering, transmission, storage, distribution, and transportation. Other research has had a more narrow focus, such as a study from scientists at Boston University and Duke University, which mapped natural gas pipeline leaks in Boston. These studies and others have used a variety of techniques to measure emissions, including engineering estimates, direct measurements at sites of interest, and measurements taken from downwind or aerial locations. In all, due to the complexity of the topic and differences in research results, there has been significant discussion, concern, and controversy surrounding the actual volumes of methane emissions arising from natural gas production, transmission, and distribution.