Methane is 86 times more effective at trapping heat over a 20-year-period than carbon dioxide
Methane emissions from the United States oil and gas fields during 2010-2019 were 70 per cent higher than the official figures of the US Environmental Protection Agency (EPA), a new study has found.
Oil and gas fields here released 14.8 teragrams (Tg) of methane annually from 2010-2019, estimated the study published in journal The Proceedings of the National Academy of Sciences on April 17, 2023.
Similarly, estimates from Canada and Mexico were pegged at 2.6 and 1.2 Tg per year, respectively. They are 67 per cent and 50 per cent higher than the country’s national reports.
“The EPA does not account for ‘super-emitters’ — devices that emit anomalous amounts of methane because of malfunctioning equipment or poor operational practices,” Daniel J Jacob, professor at Harvard University and the study’s lead author, told Down To Earth.
Methane, the primary component of natural gas and a byproduct of fossil fuel exploration, is 86 times more efficient at trapping heat over a 20-year-period than carbon dioxide. It is released from a range of sources, including wetlands, agriculture (livestock, rice), waste (landfills, wastewater) and fossil fuel drilling (coal, oil, gas).
It is technically feasible to curb more than 70 per cent of emissions from oil and gas operations, the International Energy Agency estimated.
The US leads the world in terms of methane emissions from oil and gas, according to United Nations Framework Convention on Climate Change.
Jacob and his colleagues from China, the Netherlands, the US and the United Kingdom analysed surface measurements and satellite data to quantify methane emissions.
“We were interested in better quantifying oil and gas emissions, their trends, and what is driving them,” Jacob said.
The team found that methane emissions in the US rose to 15.9 Tg per year in 2014 from 14.6 per annum in 2010, plummeted to 13.6 per year in 2017, and spiked again to 15.6 per annum in 2019.
Emissions from 2010-2014 went up by 9 per cent. The researchers said this was associated with a rise in oil and gas production by 34 per cent and an increase in the number of active wells by 27 per cent. Sustained drilling of new wells was also likely responsible.
The drop in methane emissions from 2014-2017 was linked to a 60 per cent reduction in the development of new wells.
However, total oil and gas production and active wells remained stable. This was likely fuelled by a decrease in annual crude oil prices by about 50 per cent over the period, the researchers noted.
The surge in methane emissions from 2017-2019 is likely explained by a revival of oil and gas production, which increased by 30 per cent in this period.
“The number of active wells and new wells was 8 per cent higher in 2017-2019 than the 2015-2016 mean, reflecting the upswing of oil price,” the researchers wrote.
However, methane intensity — methane emitted per unit of methane gas produced — steadily declined post-2010. During 2010-2019, the mean methane intensity from the US oil and gas sector was 3.1 per cent, according to their calculations. It went down by 0.13 per cent annually, from 3.7 per cent in 2010 to 2.5 per cent in 2019.
Methane intensity decreased despite increased oil and gas production from 2017-2019. An improvement in methane intensity coincides with the implementation of New Source Performance Standards for the oil and gas sector, the researchers highlighted. These standards tightened emission standards for various production facilities and processes, including fugitive emissions from well sites.
But sustaining this decrease in methane intensity could be challenging as oil and gas fields approach maturity and wells become less productive, the researchers explained, adding that a new approach to ensure the decline would be necessary.
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