Searching for methane leaks,
scientists find “ultra emitters”
The fossil fuel industry is releasing
millions of metric tons of methane gas in giant plumes during
extraction and transportation of those fuels—at high costs for the
climate, society, and even the industry’s pocketbooks.
Although methane emissions are relatively
low compared to CO2 emissions, each ton has a whopping
30 to 80 times the relative warming potential (depending on the
timescale of interest). On the plus side, methane has a much shorter
atmospheric lifetime—roughly nine years. So
reining in emissions as soon as possible represents one of the
better bets for lowering temperatures in the coming decades.
But to date, methods for detecting
methane emissions have been limited, and it has been challenging to
find, measure, and curtail all anthropogenic sources. A
recent study describes how researchers used a European Union
satellite to carry out a global survey of unusually large methane
plumes, finding 1,800 “ultra-emitters” during the time frame of 2019
to 2020. Two-thirds of these emitters were connected to the oil and
gas industry, and just three countries—including the US—were
responsible for the majority of the problem.
Eliminating these leaks could prevent
about 0.005° C of warming over the next 10 to 30 years, potentially
saving society billions of dollars in climate-related costs. Many such
leaks are due to avoidable issues like maintenance practices and
equipment failures—a particularly egregious way to heat up the planet.
Tracking methane
Past research has shown that at least a
third of anthropogenic methane comes from the fossil fuel
industry. However, due to the lack of required reporting for
unintentional—or even intentional (during routine maintenance)—methane
leaks, this figure largely underestimates actual emissions.
“I'm glad that we’re starting to
reconcile the atmospheric data sets and what we report because we
cannot continue to be blind and then use numbers that we know are
completely underestimating the truth,” said lead author
Dr. Thomas Lauvaux. “It's really hard to imagine that some
policymakers are working with numbers that are completely bogus.”
Although these leaks account for only
8–12 percent of the industry’s total methane emissions, every
opportunity to save even a fraction of a degree of warming is still
important for reaching climate targets. But these leaks are hard to
track, and weeks-long plane surveys—such as those used to monitor
methane emissions from
Californian landfills—won’t work for global emissions.
As a result, researchers have turned to
tools such as the European Space Agency’s
Sentinel 5-P satellite and the onboard
TROPOspheric Monitoring Instrument (TROPOMI). Using data collected
by these instruments, the team systematically searched for methane
releases of more than 25 tons per hour. Critically, the monitoring
provided daily “snapshots” that allowed the researchers to estimate
how much total methane was being lost during these events.
“Initially, we were quite disappointed
because we discovered that the sensitivity of our system was pretty
low (>25 tons/hour), but then we couldn't believe how many of these
giant blooms we discovered,” said Lauvaux. “If you don't have a
satellite covering the world every day, you might not see many of
them, and that's how they've been able to avoid the
documentation—because we didn't have this global matrix solution
before.”
The data set also picked up
ultra-emitters from coal, agriculture, and waste management (33
percent of total detections), but the majority came from oil and gas
production or transmission facilities. Unsurprisingly, these were
mostly in some of the largest fossil fuel basins around the world:
Turkmenistan, Russia, the United States, Iran, Kazakhstan, and
Algeria.
In total, these leaks released 8 million
metric tons of methane per year. Of this, Turkmenistan and Russia were
responsible for close to 1 million metric tons per year each, while
the US ranked third, with a little under 0.5 million metric tons per
year.
Potential savings
In addition to locating these
ultra-emitters, the researchers used three mitigation analyses to
calculate the costs—and potential savings—of preventing these
emissions. (The analysis used material from the International Energy
Association
Methane Tracker 2021, the US
Environmental Protection Agency's Global
Non-CO2 Greenhouse Gas Emission Projections & Mitigation:
2015-2050, and the International Institute for Applied Systems
Analysis.) Across nearly all scenarios, the results showed
significant financial savings—on the order of $200 million USD per
year for Turkmenistan and $100 million for Russia and the US.
“You could imagine why, for example, in
the middle of Siberia, you would get the minimal investment in terms
of staff, but when we found ultra-emitters in non-remote parts of the
US like Pennsylvania and Oklahoma, we were shocked,” added Lauvaux.
“Why haven't they [fixed these] earlier? Is it the lack of staff? This
is something of a mystery and needs a longer conversation with experts
in the field.”
Beyond the financial gains, the authors
also looked at the societal benefits of avoiding these emissions.
According to the
Global Methane Assessment, each ton of methane causes $4,400 USD
of climate damage to human health, labor productivity, crop yields,
and other impacts. Using that figure, the authors projected societal
savings of over $6 billion USD for Turkmenistan, $4 billion for
Russia, and $1.6 billion in the US.
Because TROPOMI can only detect plumes
larger than 25 tons per hour, there are still many smaller leaks that
researchers haven’t measured yet (particularly in the US Permian
Basin, which produces 10 percent of US natural gas but which was
excluded due to the high density of small and medium emitters). To
address this, several satellite programs are in development to make
higher-resolution worldwide surveys in the near future.
“We know we're still missing so many
emissions and we’re nowhere close to a really effective surveillance
program, but future global views will help see if policies are
effective, and we can keep [the industry] accountable,” said Lauvaux.
“We also know that [preventing these leaks] is totally doable—we have
great data sets from places like Saudi Arabia, and we have found very
few leaks. So some countries are already able to do a very good job.”
K.E.D. Coan K.E.D. Coan is a freelance science writer covering
climate and environment stories at Ars Technica. She has a Ph.D. in
Chemistry and Chemical Biology.
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