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Diving Deeper

Other Sources of Methane

Related Focus Area: Super Pollutants

While oil and gas methane is the number one industrial source of methane pollution, reductions in other sectors are not only economically justified but absolutely necessary to realize necessary emission reductions.

Emissions come from coal mining operations, landfills, wastewater treatment, and manure management operations. CATF has worked to develop an understanding of methane emissions at coal mines and landfills, including both technologies and the barriers to methane abatement, and we work to develop and implement policy and regulatory solutions that can be applied both in the US as well as internationally.

Coal Mine Methane

Globally, coal mining is responsible for 9 percent of total methane emissions. Reducing these emissions will improve mine safety, local air quality, reduce global warming, and provide a cleaner burning fuel for use at the mine or for sale.

Methane in coal seams is created as part of the same geological process that leads to the formation of coal. Large quantities of methane are typically trapped in or near the coal seams and are released during mining operations. Methane is emitted from a number of sources and operations:

  • Degasification systems at underground coal mines;
  • Ventilation of air from underground mines;
  • Abandoned or closed mines;
  • Surface mines; and
  • Fugitive emissions from post-mining operations.

Underground coal mines are the single largest source of coal mine methane (CMM) emissions. In these mines, methane is removed to maintain safety for the miners. Methane concentrations between 5 and 15 percent in the air of a coal mine represents an explosion hazard. Mines can be made safe through the use of large-scale ventilation systems that move massive quantities of air through the mines. These systems also release large amounts of very low concentration ventilation air methane (VAM) into the atmosphere. Capturing these low concentrations of methane from VAM and utilizing it rather than venting has in the past proven difficult, but new technologies have recently been developed and deployed to oxidize the methane in ventilation air.

In addition, substantial reductions in total methane release can be achieved by pre-draining the methane from the coal seam, known as degasification, prior to the coal being mined and also draining methane from post-mining operations, known as “gob”. This reduces the amount of methane that will be released into the mine that would need to be vented through a VAM process, and it produces a very high quality gas that can be sold.

Around the world, a number of barriers exist that hinder methane abatement from coal mines. These barriers can be policy-related, financial, knowledge-based, or technology-based. Each country faces different barriers and it is important to understand what stands in the way of greater methane abatement. CATF is working to understand the barriers and to develop innovative ways to overcome them. CMM abatement should play an important role in mitigating the impacts of climate change.

Landfill Methane

Landfill methane emissions result from the decomposition of organic matter by bacteria in a municipal solid waste facility. Globally, landfills account for approximately 11% of methane emissions. The primary landfill emissions reduction options involve the collection and combustion (through flaring or energy use) of gas produced within the landfill. Some promising techniques are being developed that could substantially increase the effectiveness of collection.

Longer term reduction options include development of waste management alternatives such as the use of bioreactor (aerobic and anaerobic) landfills to promote organic waste decomposition and gas collection, better conversion of collected gas and better collection of gas. In addition, the prevention of landfill methane emissions can also be achieved through better waste management including, recycling, composting, anaerobic digestion, and thermal processing. CATF is working to implement better landfill methane policies and regulations in the US and to understand the long term management solutions that can be utilized to drastically reduce landfill methane on a global scale.