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Sources of Methane - Energy Related

Coal | Oil | Gas

Introduction

The bulk of energy related methane emissions arise from methane release during fossil fuel extraction and transportation. Some methane is also produced during fossil fuel combustion, with sources such as fossil fuelled power stations, transport and heating all being significant contributors to atmospheric methane concentrations. The total global methane emission estimate from energy related sources is around 100 million tonnes each year.

Coal

At 30-50 million tonnes of methane emission per year coal mining remains a big source of man-made methane, despite the decline of coal mining here in the UK. The bulk of global methane emissions come from only a few relatively deep mines around the world.

During the geological process of coal formation methane is formed and some of this then remains trapped until released by mining operations. Generally, the deeper the coal seam, the greater the amounts of methane that are trapped. In shallow and open cast mines, the trapped methane is often released directly to the atmosphere during mining. In deeper mines the methane is often released via ventilation shafts to prevent potentially dangerous methane concentrations building up.

Strategies to reduce methane emissions from coal mines include recovery of coal mine methane both during construction, use and afterwards. Such recovery can be economically viable, particularly in deep mines, given sufficient quantities of methane, and can substantially reduce emissions to the atmosphere.

Oil

As with coal, the geological formation of oil can result in large methane deposits associated with the oil. During oil drilling and extraction, the trapped methane is released to the atmosphere. Targeted collection of the methane associated with oil can vastly reduce emissions from this source, with the collected methane being flared off as carbon dioxide or even providing an additional fuel source.

Gas

The loss of methane during natural gas extraction is obviously something which has both a direct greenhouse gas and an economic cost. Nevertheless, significant amounts of methane are lost during both extraction and transfer of methane above ground. It is estimated, for example, that in the 1990's around 6 percent of the methane piped across Russia was lost due to leaks. More efficient collection techniques, improved targeting of buried methane deposits and better maintained transfer pipelines could all help reduce incidental methane emissions from this source.


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