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* GRAPHIC-Global methane intensity: https://tmsnrt.rs/318gDAX
* Methane emission estimates by country: https://tmsnrt.rs/2Yx4aou
* GRAPHIC-Russian methane emissions estimates: https://tmsnrt.rs/3ex9wG7
* GRAPHIC-Sources of Russian methane: https://tmsnrt.rs/2Z0ZO8p
By Shadia Nasralla
LONDON, June 26 (Reuters) - Last fall, European Space Agency satellites detected huge plumes of the invisible planet-warming gas methane leaking from the Yamal pipeline that carries natural gas from Siberia to Europe.
Energy consultancy Kayrros estimated one leak was spewing out 93 tonnes of methane every hour, meaning the daily emissions from the leakage were equivalent to the amount of carbon dioxide pumped out in a year by 15,000 cars in the United States.
The find, which has not been reported, is part of a growing effort by companies, academics and some energy producers to use space-age technology to find the biggest methane leaks as the potent heat-trapping gas builds up rapidly in the atmosphere.
Kayrros, which is analysing the satellite data, said another leak nearby was gushing at a rate of 17 tonnes an hour and that it had informed Yamal's operator Gazprom about its findings this month.
Gazprom did not immediately respond to requests for comment about the leaks identified by Kayrros.
Up to now, estimates of greenhouse gas emissions from industries have relied mainly on paper-based calculations of what's pouring out of tailpipes and smokestacks, based on the amount of energy consumed by people and businesses.
But as satellite technology improves, researchers are starting to stress test the data - and the early results show leaky oil and gas industry infrastructure is responsible for far more of the methane in the atmosphere than previously thought.
Such a revelation would heap pressure on energy companies – already targeted by climate activists and investors for their contribution to carbon dioxide emissions - to find and plug methane leaks.
The new satellite discoveries of methane leaks could also lead to more stringent regulatory regimes targeting natural gas, once seen as a "clean" fossil fuel, as governments seek to combat climate change, experts say.
While scientists generally agree that calculating emissions based on consumption works well for carbon dioxide, it is less reliable for methane, which is prone to unexpected leaks.
Methane is also 80 times more potent during its first 20 years in the atmosphere and scientists say that identifying methane sources is crucial to making the drastic emissions cuts needed to avoid the worst impacts of climate change.
"What this now shows is that the avoidance of that fossil leakage actually can have a larger impact than what was anticipated earlier," said Imperial College London climate scientist Joeri Rogelj, who is one of the authors for reports by the Intergovernmental Panel on Climate Change (IPCC).
A study in February's Nature magazine reinforced the idea that the oil and gas industry produces far more methane than previously thought as it suggested emissions of the gas from natural causes have been significantly overestimated.
The findings don't let farming off the hook - it's still responsible for a quarter of the methane in the atmosphere - but they suggest mud volcanoes and natural oil and gas seepages have been taking some of the heat for the energy industry's leaks.
Some big oil and gas companies such as BP and Royal Dutch Shell are tackling the issue by investing in satellite companies or signing monitoring deals so they can find and plug their leaks and stick to pledges to slash emissions.
The push to detect emissions from the sky began when U.S. advocacy group Environmental Defense Fund (EDF) and universities including Harvard used aerial measurements to show methane leaks from America's oil and gas heartland were 60% above inventories reported to the U.S. Environmental Protection Agency.
That 2018 report was pivotal, said Christophe McGlade, a senior researcher at the International Energy Agency (IEA).
"What they found from actual ground and aerial measurements is that the engineering-based approach can really underestimate total emissions," he said. "Maybe if emissions were higher in the United States than previous estimates, maybe they were higher in other parts of the world too?"
A year later, Canadian greenhouse gas monitoring company GHGSat found another major leak at pipeline and compressor infrastructure near the Korpezhe field in Turkmenistan.
In an October report, GHGSat estimated the leak released 142,000 tonnes of methane in the 12 months to the end of January 2019 and said then it was the biggest on record.
GHGSat said the leak was plugged in April 2019 after state oil company Turkmen Oil was notified. Turkmen Oil officials could not be reached for comment. The company declined to comment when asked about it in November.
"That one emission that we found together represents about one million cars taken off the road per year," said GHGSat founder Stephane Germain.
Now, the more recent Kayrros discovery has added to the evidence that undetected methane leaks from the energy industry are a global issue – and a major one.
RUSSIA IN THE SPOTLIGHT
Kayrros said its analysis of the satellite data showed concentrations of methane around compressor stations along the pipeline linking Russian gasfields to Europe.
The Yamal-Europe pipeline stretches 2,000 km (1,250 miles) from Germany through Poland and Belarus to Russia where it joins the 2,200 km SRTO–Torzhok pipeline to Siberia's gasfields.
Gazprom estimated that about 0.29% of the 679 billion cubic metres of gas it moved through its pipeline network escaped as methane emissions in 2019. Yamal has an annual capacity of about 33 billion cubic metres.
"These figures correspond to the best global practices," Gazprom said in a June 10 statement about its emissions.
Kayrros also discovered leaks from oil and gas installations in the Sahara Desert in North Africa.
"Early results show that the estimates we have been relying on for the last years and decades are probably too low and we're finding more methane coming out of various industries and regions than we thought was the case," said Christian Lelong, director for natural resources at Kayrros.
McGlade said the IEA increased the projected contributions of several countries in central Asia and North Africa in its Methane Tracker this year because of the satellite detections.
He singled out Russia as one country where official methane emissions estimates were likely too low.
According to current IEA estimates of methane emitting countries, Russia is closely followed by the United States, with other large oil and gas producers such as Iraq, Iran and Saudi Arabia further down the list.
"Our estimates suggest that Russia is actually among the higher emitters globally. There does appear to be evidence from satellites of leaks along some of its large gas pipeline routes," McGlade said.
The Kremlin did not immediately respond to requests for comment about the IEA estimates.
The scrutiny from space is set to intensify. GHGSat aims to launch two new satellites this year while the EDF advocacy group plans to launch its own satellite in 2022.
The U.S. National Aeronautics and Space Administration (NASA) is also working on a satellite monitoring programme for greenhouse gas emissions, specifically in the United States.
Shell signed a deal with GHGSat last year to work towards covering its sites globally, saying it hopes to get its methane leakage rate down to 0.2%, or below, by 2025.
BP is planning to cover its sites with constant measurements by 2023 and invested $5 million this month in Satelytics, an analytics firm that tracks methane emissions using satellites.
BP, Shell and U.S. non-profit EDF - along with Eni, Total, Equinor and Wintershall Dea - sent policy recommendations to the European Union in May, asking the world's biggest gas importer to standardise the gathering of methane emissions data by 2023, using satellite technology.
U.S. oil companies have also been exploring ways to detect methane emissions, said Howard Feldman, senior director for regulatory and scientific affairs at the American Petroleum Institute.
Exxon Mobil Corp, for example, said this year it was field testing eight detection methods, including satellites and aerial surveillance with drones, helicopters and planes.
(Additional reporting by Vladimir Soldatkin; Editing by Richard Valdmanis, David Clarke and Jon Boyle)