You may be surprised to learn that methane is released into the atmosphere as a direct result of mining coal. You can read the EPA report on this to learn more: Frequent Questions About Coal Mine Methane.
From the EPA site (retrieved March 5, 2020):
By 2020, global methane emissions from coal mines are estimated to reach nearly 800 MMTCO2E, accounting for 9 percent of total global methane emissions. China leads the world in estimated coal mine methane (CMM) emissions with more than 420 MMTCO2E in 2020 (more than 27 billion cubic meters annually). Other leading global emitters are the United States, Russia, Australia, Ukraine, Kazakhstan, and India.
Download the full spreadsheet here via the button at the bottom right of Excel spreadsheet above.
This analysis is referenced in Straight facts on the environmental impact of coal: CO2, pollution, land, and water.
Code: m114 kWhCoalCH4