Pennsylvania’s prolific natural gas industry has made the state the No. 2-producing gas state in the country, second only to Texas. But the industry also releases a lot of methane, a potent greenhouse gas responsible for around 25 percent of global warming, a new analysis by a group of scientists working with the Environmental Defense Fund has found.
The analysis found Pennsylvania’s shale gas industry leaked seven times more methane in 2017 than state reporting for the year indicates. It also found the conventional natural gas industry leaks an even larger amount of methane, despite producing a mere 2 percent of the state’s gas.
The analysis comes as the state is creating methane rules for thousands of existing wells. The Department of Environmental Protection will begin taking comments on the rule later this month.
“The EDF data highlights the need to reduce methane, and the Wolf Administration/DEP recognizes the need to act quickly to reduce methane pollution from wells and other natural gas infrastructure,” DEP spokeswoman Lauren Fraley said in a statement.
All told, the EDF analysis found oil and gas industry leaks 16 times more methane than state figures show, though more than half of that came from shallow, or conventional, gas producers who aren’t required to report their methane emissions to the state.
A spokesman for the Pennsylvania Independent Oil and Gas Association, which represents conventional oil and gas companies in the state, said the group had not yet reviewed the report and couldn’t comment on it.
“The association will be commenting on DEP’s upcoming rulemaking on behalf of its members,” spokesman Dave Mashek said in an email.
Dave Spigelmyer, president of the Marcellus Shale Coalition, said in a statement that the industry is improving its methods at making sure methane — a potent climate warming agent and the main component of natural gas — stays inside pipelines.
“Through new technologies and best practices — such as robust leak detection and repair programs and vapor recovery systems — operators continue to make significant progress to ensure natural gas reaches market,” Spigelmyer said.
The analysis follows a similar analysis of Pennsylvania emissions the group conducted two years ago. The latest study found twice the amount of gas leaking out of production in the state — over 1 million tons, or 57 billion cubic feet, which is around 1 percent of the gas produced in the state.
Hillary Hull, EDF’s senior manager for research and analytics, said the group used a different model that it believes more accurately depicts the amount of gas leaking from the natural gas system, and used updated gas production data from 2017.
The model was the same used in a 2018 EDF study, published in the journal Science, that drew from more than a dozen other peer-reviewed studies. That study put the rate of methane emissions from domestic oil and gas operations at 2.3 percent of total production per year, 60 percent higher than the EPA’s estimate.
Hull said the reason why the EDF analysis found higher levels of emissions than those reported by industry was that companies report their emissions based on formulas created by the EPA. The formulas estimate how much gas a well will leak based on what kind of equipment the company is using.
“What we find is that when you actually go out and measure the emissions in a location, the emissions measured are always much higher than the emissions estimated,” Hull said.
She says part of the reason for this is that the formulas companies use don’t account for abnormally leaky wells, so-called ‘super-emitters’ — which Hull said are responsible for most of the industry’s methane emissions.
“We have reason to believe that most of those emissions are coming from malfunctions and abnormal process conditions,” Hull said.
Hull said those “abnormal” emissions aren’t accounted for in the data companies report to the state.
Arvind Ravikumar, assistant professor of energy engineering at Harrisburg University of Science and Technology, said the analysis confirms other studies showing official federal and state inventories underestimate how much methane is escaping the natural gas production system.
“This is not a one-time exception,” said Ravikumar, who was not involved in the EDF analysis but who worked on an EDF-funded methane project as a post-doctoral fellow several years ago. “This is just one in a long line of methane emission observations that suggests methane emissions are higher than what’s been reported.”
Potent Greenhouse Gas
Methane is the main component of natural gas, and, when burned, produces around half the carbon dioxide of coal. But when it’s leaked into the atmosphere, it is a powerful greenhouse gas — 28 times more powerful than CO2 over the course of a century, according to the UN’s Intergovernmental Panel on Climate Change, and 84 times more powerful over the course of 20 years.
Scientists say that any methane leaked into the atmosphere detracts from the climate benefits of the natural gas industry, whose growth has largely been credited with reducing the country’s dependence on carbon-intensive coal.
Since methane is relatively short-lived — it lasts in the atmosphere around 10 years — controlling its release is a quick way to limit climate change, said Kenneth Davis, professor of atmospheric and climate science at Penn State. By contrast, carbon dioxide lasts for centuries in the atmosphere, Davis said.
“That’s one reason there’s a lot of attention on methane. It’s because it’s a relatively easier target for control of climate than CO2,” said Davis, who was not involved with the EDF’s latest analysis but who did contribute to the 2018 Sciencepaper. “If we reduce methane emissions we will reduce methane concentrations relatively quickly.”
Allen Robinson, professor of engineering and public policy at Carnegie Mellon, who reviewed the analysis for EDF, said the leak rates found in the study were still low enough to make using natural gas better than using coal from a global warming perspective.
But he said since natural gas still creates CO2 when burned, it still poses a threat to stabilizing the earth’s climate in the long term.
“We’re making progress by going from coal to gas, with this leakage rate,” Robinson said. “But if we’re really thinking about the long term of where we need to get to, this isn’t going to be good enough.”
This story is produced in partnership with StateImpact Pennsylvania, a collaboration among The Allegheny Front, WPSU, WITF and WHYY to cover the commonwealth's energy economy.