When scanning for emissions from a mud volcano in western Turkmenistan in January 2019, a satellite called Claire came across a large plume of methane drifting across the landscape. … The company operating the satellite, GHGSAT passed details via diplomats to officials in Turkmenistan, and after a few months the leaks stopped. This largely unknown incident illustrates two things: that satellites can play an important role in spotting leaks of greenhouse gases and, rather worryingly, that the extent of such leaks is often greatly underestimated. The data from Claire suggested the leak in Turkmenistan had been a big one…142,000 tonnes of methane. This made the Turkmenistani leak far bigger than the 97,000 tonnes of methane discharged over four months by a notorious blowout at a natural-gas storage facility in Aliso Canyon, California, in 2015, which is reckoned to have been the worst natural-gas leak yet recorded in America. There have been other big leaks, too…
The reason for concern is that although methane, the main constituent of natural gas, does not linger in the atmosphere for anywhere near as long as carbon dioxide does, it is a far more potent heat-trapping agent. About a quarter of man-made global warming is thought to be caused by methane. And between a fifth and a third of the methane involved is contributed by the oil and gas industry. Methane can be detected spectroscopically. Like other gases, it absorbs light at characteristic frequencies. With a spectrometer mounted on a satellite it is possible to analyse light reflected from Earth for signs of the gas. As with the satellites that carry them, spectrometers come in many shapes and sizes. Tropomi can also detect the spectral signs of other polluting gases, such as nitrogen dioxide, sulphur dioxide and carbon monoxide.
Other methane-hunting satellites are coming. These include one due for launch in 2022 by Methanesat, an affiliate of the Environmental Defence Fund, an American non-profit organisation. The 350kg satellite will cost $88m to build and put into orbit. It will scan an area of land 200km wide with a resolution of 1km by 1km. According to Methanesat, it will be the most sensitive to emission levels yet, being able to detect methane concentrations as low as two parts-per-billion. Data collected by the satellite will be publicly available.
Excerpts from The Methane Hunters, Economist, Feb. 1 2020