Methane leak

A methane leak is a significant natural gas leak. The term is used for a class of methane emissions, which can come from an industrial facility or pipeline.

Satellite data enables the identification of super-emitter events (synonymous with ultra-emitters, see "Mitigation of Ultra-Emitters") that produce methane plumes. Over 1,000 methane leaks of this type were found worldwide in 2022. As with other gas leaks, a leak of methane is a safety hazard: coalbed methane in the form of fugitive gas emission has always been a danger to miners. Methane leaks also have a serious environmental impact. Natural gas contain methane, ethane, and other gases, which from the safety and environmental point of view raise major issues with atmospheric composition and human health.

As a greenhouse gas and climate change contributor, methane ranks second, following carbon dioxide. Fossil fuel exploration, transportation and production is responsible for about 40% of human-caused methane emissions. Smaller leaks than can be spotted from space comprise long tail of emissions. They can be identified from planes flying at 900 meters (3,000 ft). According to Fatih Birol of the International Energy Agency, "Methane emissions are still far too high, especially as methane cuts are among the cheapest options to limit near-term global warming".

Individual methane leaks are reported as specific events with a large quantity of gas released. An example followed the 2022 Nord Stream pipeline sabotage. Following early reports that the escape might exceed 10⁵ tonnes, The International Methane Emissions Observatory of the United Nations Environment Programme analyzed the release. In February 2023 it put the mass of methane gas in the range 7.5 to 23.0 x 10⁴ tonnes. In terms of overall human-made methane emissions, these figures are under 0.1% of the annual total.

Satellite data detection has shown that methane super emitter sites in Turkmenistan, USA and Russia are responsible for the biggest number of events from fossil fuel facilities. Estimated emissions from oil and gas ultra-emitters rank highest for Turkmenistan with 1.3 megatons (Mt) of methane per year, followed by Russia, the United States, Iran, Kazakhstan, and Algeria. Equipment failures are normally responsible for the releases, which can last for weeks.

The Aliso Canyon gas leak of 2015 has been quantified as at least 1.09 x 10⁵ tonnes of methane. Satellite data for the Raspadskaya coal mine, Kemerovo Oblast, Russia indicated in 2022 an hourly methane leakage rate of 87 tonnes; this compares to 60 tonnes per hour of natural gas leaking from the Aliso Canyon incident, considered among the worst recorded leak events.

Spain's Technical University of Valencia, in a study published in 2022, found that a super emitter event at a gas and oil platform in the Gulf of Mexico released around 4 x 10⁴ tonnes of methane during a 17-day time period in December 2021 (hourly rate around 98 tonnes). Another major event in 2022 was a leak of 427 tonnes an hour in August, near Turkmenistan's Caspian coast and a major pipeline.

Ultra-emitters of methane are characterized by producing more than 25 tons/hour of CH₄ from oil and gas activities, and are in the top 1% of methane emitters in the world. Reducing emissions from these sites can be done by enforcing leak detection and by reducing venting during routine maintenance.