Coal mines emit more methane than oil and gas

From Carbon Brief:

Methane emissions from coal mines could be more than double previous estimates, according to a new study.

The fossil-fuel industry is understood to be one of the biggest sources of atmospheric methane, primarily due to leaks from the production of oil and gas.

However, a new paper published in the Journal of Cleaner Production suggests that coal mining may actually be a bigger contributor to levels of the greenhouse gas, with emissions set to grow considerably in the coming years.

This is even more pronounced when accounting for the impact of old coal mines that continue to seep methane long after they have been abandoned. To date, attempts to curb methane emissions from mines have been limited.

The authors of the new study say there are considerable gaps in the available data, and their results are based on extrapolations from the only nations for which sufficient information was available.

Nevertheless, their findings are the latest in a string of papers to suggest methane emissions from the fossil-fuel industry have been “severely underestimated”.

Coal-mine methane (CMM) is relatively understudied. But in its most recent World Energy Outlook (WEO), published in November 2019, the International Energy Agency (IEA) attempted to quantify the global total, settling on a figure of 40m tonnes (Mt) each year from operational coal mines.

The IEA coal mine emissions estimate also comes to around half the 79Mt it estimated for oil-and-gas operations in 2018.

However, the new study estimates that CMM in 2020 will be much higher than this, some 135bn cubic metres (bcm), equating to roughly 92Mt of methane.

The authors also note that, for the first time, they developed a methodology for estimating global methane emissions from old mining sites, suggesting a considerable role for abandoned mine methane (AMM), which in the past has been largely ignored. When factoring this in, coal methane emissions in 2020 rise to 114Mt.

The authors say that using their base year of 2010, methane emissions were also higher than other recent widely cited studies and inventories.

They calculate the total volume for that year as 85Mt, around 50% higher than that of the Community Emissions Data System (CEDS) and double the Emission Database for Global Atmospheric Research (EDGAR) value.

[Read more here]

When it is pointed out that methane produces half the emissions of coal when it's burnt, coal spruikers desperately mention gas leaks ("fugitive emissions") as a counter.  But it looks more and more likely that coal mining produces as much methane as oil and gas production do.  And at least power plants using oil or gas can be quickly ramped up or down to respond to fluctuations in the supply of wind- or solar-generated electricity.   Coal power stations can also ramp up and down but only slowly and it damages them to cut output to zero.  And coal is filthier than natural gas (except for fracking).  Over the next 10 years, let's close down most of our coal-fired power stations, and switch to manufacturing processes for steel and cement which use green hydrogen or green methane instead.

Aerial view of an open-cast coal mine Belchatow, Poland.
Credit: Łukasz Szczepanski / Alamy Stock Photo