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Flares may release more methane than thought, study finds


The oil industry’s unwanted methane burning is less efficient than previously assumed, scientists said on Thursday, leading to a new estimate of greenhouse gas emissions. greenhouses in the United States are five times higher than in previous operations.

In a study of the three largest oil and gas storage tanks in the United States, researchers found that the operation, known as combustion, often fails to completely ignite methane, a gas that keeps Intense heat is often a by-product of oil production. . And in many cases, they found, flares are extinguished and do not re-ignite, so all the methane escapes into the atmosphere.

Improving efficiency and ensuring that all flares remain lit would lead to annual emissions reductions in the United States equivalent to taking nearly 3 million cars off the road, say the scientists. road every year.

One of the researchers, Eric A. Kort, an atmospheric scientist at University of Michigan. “But they’re actually more important to the climate than we realize.”

“So if we clean up our act with these flares, we’re actually going to have a much more positive impact on the climate than we realized at first,” said Dr. .

Because methane is a more potent, albeit shorter-lived, greenhouse gas than carbon dioxide, efforts to identify and reduce methane emissions have intensified in recent years.

Methane is a major component of natural gas, also known as fossil gas, which can leak into the atmosphere from wells, pipelines and other infrastructure, and is also intentionally released for maintenance or other reasons. due to other.

But a huge amount is exploding.

Gas is often produced with oil at wells around the world, or at other industrial facilities. There may be no pipes or other means to market it economically, and because it is flammable, it poses safety issues. In such cases, the gas is passed through a vertical pipe with an igniter at the top and ignited.

The International Energy Agency estimates that worldwide in 2021, more than 140 million cubic meters of methane have been burned in this way, equal to that year’s imports by Germany, France and the Netherlands.

If combustion is efficient, almost all of the methane is destroyed, converted to carbon dioxide, with little immediate climate impact. The Environmental Protection Agency, in studies conducted in the 1980s, calculated that flares destroyed 98% of the methane sent through them.

But new research shows that burning flares is actually much less effective, especially when unlit flares are taken into account. Emissions from improper combustion account for up to 10% of all methane emissions in the oil and gas industry, scientists say. The findings have been published in the journal Science.

The researchers looked at activities in the Permian and Eagle Ford basins in Texas and Bakken in North Dakota, which together account for about 80 percent of outbreaks in the United States. “The idea is that if we can do a good representation of those areas, we’ll get a good picture of what it looks like across the United States,” said Dr. Kort. They sampled the gas plumes from the flares by flying over them in a small plane.

They found that flares only destroyed about 95% of the methane, not 98%. And they found that in some basins, up to 5% of flares were not lit. That reduced the overall performance by about 91%.

Flares can be affected by wind, which may allow some unburnt methane to escape, or by the presence of other gases. Wind, changes in gas pressure or problems with the igniter can cause a flame to die out, and if not monitored regularly, flares may not light up for a long time.

Riley Duren, CEO of Carbon Mapper, a nonprofit group that will launch satellites next year to detect and monitor sources of greenhouse gas emissions, says the findings are not surprising to those who have studied emissions from oil storage tanks. and this gas and know the amount of flare made.

But the researchers’ comprehensive survey found that outbreaks of ineffectiveness “was a more systemic problem,” said Dr. Duren, who was not involved in the study.

In other parts of the world, there is little direct observational evidence of outbreak effectiveness, Dr. Duren said. But globally, he said, “it is likely that combustion and flare-ups are less efficient than assumed.”



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