Tuesday 31 May 2016

Fugitive Methane emissions from mines - US experience

Methane, one of the most potent greenhouse gases has increasingly been detected in larger volumes in many countries than would be considered to be the normal background level, based on progressive leaching from the ground and from under the sea floor. From where is it originating and in what quantities and levels ?  Part of the answer lies in research undertaken in Los Angeles and with the recent incident in the Aliso Canyon in California.

Methane is the main component of natural gas and is abundant across the planet hence mining and storage could be the most likely culprits for the increase of this gas. In a study published this year, more than a third of  Los Angeles methane emissions were from an unidentified sources and were classified as fugitive fossil emissions. Identification and tracking of 213 methane hotspots in the Los Angeles Basin revealed that 75% were of fossil origin, 20% were biogenic and 5% of indeterminate source.

The Aliso Canyon incident arose when residents in nearby towns reported smelling gas and Southern California Gas Company launched an investigation discovering a leak coming from a natural gas storage facility that had started its life almost 70 years ago as an oil well. By the time the leak was plugged, 107,000 tons of methane and 8,000 tons of ethane had been released into the atmosphere - the equivalent of greenhouse gas emissions from half a million cars over 16 weeks.  There are literally hundreds of similar sites including disused or abandoned mines and oil wells across not only the United States but Russia as well.

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