Natural gas gathering and processing plants leak much more methane than producers have reported, and even more than the Environmental Protection Agency has estimated, according to a study released Tuesday.
Researchers at Colorado State University found that U.S. gathering and processing facilities — where natural gas from nearby wells is consolidated for distribution through pipelines — leak 2,421,000 metric tons of methane each year. The facilities emit 100 billion cubic feet of natural gas every year, roughly eight times the amount previously estimated by the EPA.
Gathering facilities “could be responsible for something like 30 percent of emissions for all natural gas production,” the study’s lead researcher, Anthony Marchese, said on a press call Tuesday.
Methane is a greenhouse gas that is 86 times more effective at trapping heat than carbon dioxide over a 20-year time frame. It is the primary ingredient in natural gas.
The amount of emissions tracked in the study has roughly the same 20-year climate impact as 37 coal-fired power plants, the Environmental Defense Fund (EDF) said. The study, published in Environmental Science and Technology, is part of a series of studies organized by EDF that will compose the largest inventory of methane leaks in the U.S. natural gas industry to date. An earlier report in the series found that oil and gas operations on federal and tribal lands leaked $360 million worth of fuel in 2013.
Controlling methane emissions, especially as the United States increasingly extracts and uses natural gas, plays an important role in the effort to curtail climate change. On Tuesday, the Obama Administration proposed a new rule that seeks to regulate methane emissions from the oil and gas sector.
This study could help show producers and regulators where methane emissions are coming from.
“The gathering and processing sector, a piece of the supply chain that most people don’t even know exists, may be the biggest single fraction of emissions coming from natural gas,” Mark Brownstein, who leads EDF’s work on methane emissions, told the New York Times.
The study looked at 16 processing plants and 114 gathering facilities. On average, gathering facilities leak .47 percent of the gas they process, and at least one facility was leaking 9 percent of its gas. Marchese pointed out that 20 percent of gathering facilities had leaking storage tanks — and those facilities had three times the emissions as facilities without leaking tanks.
Processing plants were more efficient, leaking less than .01 percent, on average, the study found. Marchese speculated this difference could be because processing plants are larger and better regulated.
The discrepancy between the documented emissions rates for gathering facilities and the self-reported rate is striking: The industry reported that 500 metric tons were lost at gathering facilities. The study estimates that 1,875,000 were lost.
“Not all processing plants report,” Marchese said. In fact, only about 10 percent of facilities report emissions, and they only report combustion emissions, not leaks, he said.
Marchese pointed out that the loss rates were much higher than the industry would want.
“They want to get it down around .01 percent,” he said.
The amount of gas wasted each year in the gathering and processing phase is worth about $300 million, according to EDF.