Seen From Space: Huge Methane Leaks
By Henry Fountain, Feb. 4, 2022, NYT

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.

Dr. 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. Dr. 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 percent of methane emissions from
the industry as a whole. Requiring companies to repair these major leaks
or other problems would likely 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 like 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 like Sentinel 5 “act like wide angle lenses on cameras,” Dr. Duren said. “They give good, wide-area global situational awareness of
where hot spots are.”

Dr. Duren is also the chief executive 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,”
Dr. Duren said. “That’s going to push the detection limits down.”

https://www.nytimes.com/2022/02/04/climate/methane-leaks-satellites.html

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