Other Sources of Methane
Work Area: Methane Pollution Prevention
While the oil and gas industry and the waste sector are two of the biggest sources of methane pollution, reductions in other sectors are not only economically justified but critical to realize the full climate benefits of methane mitigation. Methane emissions also come from agriculture and coal mining operations. CATF is working to develop innovative solutions, financial mechanisms, and policies that can be applied both in the U.S. as well as internationally to minimize their climate impacts.
Methane from Agriculture
Agriculture emissions account for roughly 40% of total global anthropogenic methane emissions. Agriculture methane emissions stem most significantly from enteric fermentation, alongside rice cultivation, manure management, and residue burning – generating 3,772 MtCO2e in 2010 and projected to rise to 5,198 MtCO2e in 2050 under business-as-usual. Through ambitious mitigation activities, however, global agricultural methane emissions could fall by as much as 39% in 2050.
Country-level action is critical to reducing global agricultural emissions. Effective mitigation measures in the sector depend, however, on several factors such as the region and its natural environment, socio-economic aspects, local nutrition patterns, as well as the production system (e.g., pasture vs. barns). Furthermore, accelerated and increased research is required to evaluate the feasibility and cost of implementing these solutions, as not all are ready for implementation. Solutions for mitigating methane emissions in the agriculture sector include:
- Increasing the productivity and efficiency of ruminant livestock (such as cattle, sheep, and goats) can provide more income for farmers while at the same time reduce enteric methane emissions per animal and/or per unit of milk or meat.
- Reducing enteric fermentation. Strategies that utilize feed additives to reduce enteric fermentation are still being developed. In addition, vaccines that target the organisms that cause methanogenesis in cattle, manipulating microbiological communities in ruminant stomachs and selectively breeding animals that produce fewer emissions have been tested.
- Improving manure management. The separation of liquids from solids in manure to form two waste streams makes it possible to better direct nitrogen and phosphorus to fields that need them, reduces the costs of transporting manure to these fields, and is key in mitigating methane emissions from manure. Other effective manure management strategies may include adjusting the temperature of manure slurry and use of chemical additives, which have proven effective in reducing emissions during composting. Finally, diverting manure from being discharged into streams to being discharged onto farm fields avoids pollution and sequesters carbon.
- Capturing and using methane emissions. Digesters can be used to capture emissions from manure and use them to generate energy at both large-scale and household operations.
- Rice management strategies such as accelerating rice yield growth, removing rice straw from flooded fields, reducing flood periods, and breeding lower-methane rice can be effective in reducing methane emissions from rice production. Furthermore, improved management of water can lower rice production emissions. Methane reductions can also be achieved by plastic film mulching, rice modification, and efficient fertilizer management. Composting rice straw rather than adding it to flooded fields can aid in the avoidance of methane emissions from rice production.
CATF is advocating for funding and policy support to incentivize implementation of existing solutions to agricultural methane emissions. We are also advocating for aggressive research programs to assess and scale innovative new technologies to reduce methane emissions from the sector.
Coal Mine Methane
Coal mining is responsible for roughly 12% of global anthropogenic methane emissions. Methane in coal seams – deposits of coal that are visible within layers of rock – 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 coal deposits and are released during mining operations. Methane is emitted from a number of sources and operations, including:
- Degasification systems and ventilation air from underground mines;
- Abandoned or closed mines;
- Surface or open pit mines; and
- Fugitive emissions from post-mining operations, such as coal transport and storage.
Underground mines are the single largest source of coal mine methane emissions. Due to its threat to miner safety along with its high explosion risk, methane is removed with large-scale ventilation systems that move massive quantities of air through the mines. As a result, large amounts of very low-concentration ventilation air methane – usually containing 0.1 to 1% methane – is released into the atmosphere. Ventilation air methane emissions are responsible for nearly 70% of all underground fugitive methane emissions. Gas drained from a coal seam prior to mining can contain methane concentrations ranging from 60 to 90% methane, while draining methane from post-mining operations (gobs) can contain concentrations of 30 to 95% methane.
While financial, institutional, and even technological barriers to capturing and utilizing coal mine methane do exist, utilization of high-concentration methane as well as upgrading it to pipeline quality gas for sale, are both common practices. Technologies also exist to capture and use low-concentration ventilation air methane, however, additional research and technological advances are necessary for wide-scale implementation.
The development of robust policies and regulations are critical to reducing greenhouse gas emissions associated with the mining sector. CATF is working in conjunction with multiple organizations, institutions, and the private sector to turn these barriers into opportunities for action.