If the world is going to make a dent in emissions of methane, a potent planet-warming gas, targeting the largest emitters would probably be the most cost-effective. But there’s a basic problem: how to find them.
A new study has shown one way. Using data from a European satellite, researchers have identified sites around the world where large amounts of methane are pouring into the air. Most of these “ultra emitters” are part of the petroleum industry, and are in major oil and gas producing basins in the United States, Russia, Central Asia and other regions.
“We were not surprised to see leaks,” said Thomas Lauvaux, a researcher at the Laboratory for Sciences of Climate and Environment, near Paris, and lead author of the study, published in Science. “But these were giant leaks. It’s quite a systemic problem.”
Among gases released through human activities, methane is more potent in its effect on warming than carbon dioxide, although emissions of it are lower and it breaks down in the atmosphere sooner. Over 20 years, it can result in 80 times the warming of the same amount of carbon dioxide.
Because of this, reducing methane emissions has increasingly been seen as a way to more rapidly limit global warming this century.
“If you do anything to mitigate methane emissions, you will see the impact more quickly,” said Felix Vogel, a research scientist with Environment and Climate Change Canada in Toronto who was not involved in the study.
Among the nearly 400 million tons of human-linked methane emissions every year, oil and gas production is estimated to account for about one-third. And unlike carbon dioxide, which is released when fossil fuels are deliberately burned for energy, much of the methane from oil and gas is either intentionally released or accidentally leaked from wells, pipelines and production facilities.
“Methane typically is something you don’t want to lose,” Vogel said. It could be captured and used — for one thing, it’s the main component of natural gas. “So it’s much easier to work toward reducing emissions,” he said.
Until recently, identifying major emitters of methane has largely been accomplished through remote sensing by airplanes, drones or surface equipment, which can only spot emissions over relatively small areas, usually for relatively short periods. These methods can be revealing — a 2019 New York Times investigation using airborne sensors, for example, showed large leaks from facilities in the Permian Basin in West Texas, a major oil and gas producing area.
Satellites can provide much broader, continuous coverage, but at a lower resolution that makes it difficult to pinpoint emissions sources.
Lauvaux and his colleagues found, however, that they could detect extremely large emitters — those releasing more than 25 tons per hour — in data from a sensor aboard a European satellite, Sentinel 5. Using data from 2019 and 2020, they located about 1,200 of these ultra emitters, a large portion of them from Russia, Turkmenistan, the United States, the Middle East and Algeria.
Total emissions from these sites were estimated at about 9 million tons per year. In terms of its potential to warm the planet, that much methane is equivalent to about 275 million tons of carbon dioxide, which is the total carbon footprint of 40 million people, based on the global average per capita.
The reported amount of methane does not include amounts from some regions, including the Permian Basin and oil-producing areas in Canada and China, where overall emissions were so high it was not possible to distinguish large individual sources. Lauvaux estimated that if ultra emitters from those regions were included, the annual methane total would be about double.
That would account for more than 10% of methane emissions from the industry as a whole. Requiring companies to repair these major leaks or other problems would probably help reduce emissions more quickly and at lower net cost than detecting and repairing countless thousands of much smaller leaks.
Even though the researchers were able to detect huge emission plumes, the satellite resolution, about 15 square miles, is not high enough to give the exact location of the source — the specific pump or pipeline section that is leaking, for example.
So the research points to a need to use multiple methods to detect emissions sources, said Riley Duren, a researcher at the University of Arizona and one of the study authors. Airborne or ground-based sensors could be used to follow up at sites detected by satellites such as Sentinel 5.
There is also soon to be a new generation of methane-detecting satellites with much higher resolution, capable of more precisely pinpointing sources.
Satellites such as Sentinel 5 “act like wide-angle lenses on cameras,” Duren said. “They give good, wide-area global situational awareness of where hot spots are.”
Duren is also CEO of Carbon Mapper, a public-private partnership behind a project that will use a constellation of satellites. It and another satellite, MethaneSAT, a project of the Environmental Defense Fund, “will act more like a telephoto lens,” he said.
“We’re going to see dramatic advances in space-based monitoring of methane,” Duren said. “That’s going to push the detection limits down.”
(Author: Henry Fountain)/(c.2021 The New York Times Company)
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