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Mitigating Methane

Katie McWilliams

In long-term scenarios, methane is extraordinarily damaging to the environment. A greenhouse gas with a lifespan of approximately 9-15 years, methane can be 20 times more effective at trapping heat than carbon dioxide over a 100-year period (i). Because of its potency and relatively short lifespan in the atmosphere, lowering methane emissions is one of the quickest ways to see a measurable impact on reducing greenhouse gases and mitigating climate change (ii).

Methane emissions stem from a variety of both natural and anthropological sources. In the natural environment, methane is commonly released into the atmosphere by wetlands, permafrost soils, wildfires, and large bodies of water (iii). However, more than 60% of global methane emissions are the result of anthropogenic activities (iv). In the United States, the largest contributors include landfills, coal mining, natural gas systems, and livestock management (v).

To curb the environmental impact from these industries, the United States Environmental Protection Agency has developed a variety of programs designed to reduce emissions. Because methane is a primary component (around 95%) of natural gas, captured methane can be used as a valuable energy source (vi). Capturing emissions and converting them to natural gas not only reduces the environmental impact, but also provides significant energy and economic benefits (i). Many strategies for capturing methane are cost-effective because the methane can be converted to energy and used as fuel, or can be sold to natural gas pipelines for an external profit (vi). Companies in the U.S. that participate in such programs are not only reducing their environmental impact, but are doing so at very little to no cost (i).

The government sponsors a methane-capturing program for each of the four industries responsible for the majority of anthropogenic emissions in the U.S. These programs include the AgSTAR program, the Landfill Methane Outreach Program (LMOP), the Gas STAR Program, and the Coal Bed Methane Outreach Program (CMOP).

AgSTAR Program

The livestock industry contributes to methane emissions in the U.S. mostly through the normal digestive processes of ruminant animals such as cattle, sheep, and goats. Large farms, especially dairy and swine operations, use liquid manure management systems that also produce methane (v). Combined, ruminant digestion and waste management systems are the single largest source of methane emissions in the country.

The AgSTAR program promotes the use of biogas recovery technology to capture and reuse methane produced by the livestock. A biogas system contains the methane and combusts it to produce electricity or heat. Since 1994, AgSTAR has installed over 150 biogas technology systems throughout the country. These systems have been funded mostly by government programs such as the USDA’s Rural Development program, which alone has awarded $34 million in grants (ix).

The biogas technology systems reduce emissions in two ways: first, methane that ordinarily would be released into the atmosphere is prevented from escaping. Second, if the captured methane is converted into an energy source and used, less fossil fuel is needed to generate energy. This reduces what would have been future emissions from the burning of the avoided fossil fuels (ix). In 2009 alone, biogas systems generated 341,000 MWh of electricity and eliminated the equivalent of almost 1.2 million metric tons of greenhouse gases from the atmosphere.

Landfill Methane Outreach Program

Landfills are the second largest source of methane, and are responsible for 23% of U.S. anthropogenic emissions, or the equivalent of 32 million metric tons per year (ii). As trash and waste decomposes anaerobically, or without the assistance of oxygen, it generates methane gas (v).

LMOP is a voluntary assistance program that encourages participants to capture and use methane as an energy source. The gas is extracted and contained by a vacuum system, then stored in wells. Once collected, the methane is processed, treated, and converted to natural gas. It can then be used to generate electricity for the landfill or other nearby locations, thus eliminating the need to burn other fossil fuels or pay for energy use. The natural gas can also be sold to pipelines as an additional source of revenue to pay for the capturing/conversion system (ii).

LMOP participants that install energy conversion technology can reduce their methane emissions by 60-90%. The gas captured has been used to fuel power plants, vehicles, manufacturing facilities, and even individual homes (ii). Currently, there are 519 landfills that capture and convert methane to use as fuel. Another 530 landfills have been identified as good candidates for future projects. If the total number of landfills participating reaches 1,000, it is estimated that the energy produced could power 720,000 homes.

Gas STAR Program

The natural gas and petroleum industry is responsible for 18% of all emissions, making it the third largest source of methane in the U.S. Methane is emitted during most natural gas production phases - from processing, to storing, to distribution (v). Beginning in 1993, the Gas STAR program encouraged participating companies to invest in emission reducing technologies and also document their activities (vii). Today, 60% of all companies within the natural gas industry are program members.

In the 17 years since the program began, emissions have been reduced by 822 billion cubic feet, which has the same atmospheric effect as eliminating carbon dioxide emissions from six million homes. The figure is also comparable to eliminating greenhouse gas emissions from 8.5 million vehicles, and it would require 10.5 million acres of pine forests to sequester that amount of carbon. Also, methane captured, converted to natural gas, and subsequently sold has earned the involved companies a combined $802 million dollars in revenue.

Coal bed Methane Outreach Program

The fourth largest source of emissions in the U.S. is methane released through mining operations. Methane is generally captured and removed from the mine by a ventilation system, since it is explosive and hazardous to miners working in a confined space. As a result, the capture and conversion of coalmine methane is beneficial not only to the environment, but also to the mine (as a valuable source of energy and revenue) and the miners. With lower concentrations of methane left in the mines, the chance of a methane-induced explosion is smaller (x).

By 2006, 86% of all coalmine methane was being captured. This equaled a 16% reduction in emissions since 1994, when the CMOP program began. In those 12 years, the volume of methane gas captured was the equivalent of eliminating 216 million metric tons of carbon dioxide from the atmosphere. Methane reductions from CMOP had the same effect as eliminating 39 million vehicles from the roads for one year, or shutting down 46 coal-fired power plants. Also, enough methane was captured to power 28 million homes for one year.

Another benefit of capturing coalmine methane is that the cost of the technology to capture and convert it to natural gas is equal, if not less than, the potential revenue (x). By either selling the natural gas or using it as an internal energy source, the coal mining industry gains roughly $600 million in profits each year (viii).

Conclusion

Together, companies participating in these four government-sponsored programs have lowered U.S. anthropogenic methane emissions by 11% since 1990. While this may not seem to be an overwhelming reduction, the decreases have occurred in spite of overall economic growth within the industries (i). If the number of participants in methane mitigation programs continues to increase, the overall benefits to the United States (both environmental and economical) could be substantial.

References

i. U.S. Environmental Protection Agency, "Methane," 5 March 2010.

ii. U.S. Environmental Protection Agency, " Landfill Methane Outreach Program ," 26 April 2010.

iii. U.S. Environmental Protection Agency, "Methane: Sources and Emissions," 4 May 2010.

iv. IPCC 2007a: Climate Change 2007: The Physical Science Basis Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Solomon, S., D. Qin, M. Manning, Z. Chen, M. Marquis, K.B. Avery, M. Tignor and H.L. Miller (eds.). Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, 996 pp.

v. U.S. Environmental Protection Agency, "2010 U.S. Greenhouse Gas Inventory Report," 15 April 2010.

vi. U.S. Environmental Protection Agency, "Methane: Projections and Mitigation Costs," 5 March 2010.

vii. U.S. Environmental Protection Agency, "Natural Gas STAR Program: Accomplishments," 7 December 2009.

viii. U.S. Environmental Protection Agency, "The AgSTAR Program: Basic Information," 24 October 2008.

ix. U.S. Environmental Protection Agency, "The AgSTAR Program: Accomplishments," 20 April 2010.

x. U.S. Environmental Protection Agency, "Coalbed Methane Outreach Program (CMOP): Basic Information," 18 March 2010.

SPRING 2010 Climate Alert

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