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Encyclopedia Dubuque

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Affiliated with the Local History Network of the State Historical Society of Iowa, and the Iowa Museum Association.




METHANE

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METHANE. Methane (CH4) is the second most common greenhouse gas emitted in the United States from human activities. In 2013, CH4 accounted for about 10% of all U.S. greenhouse gas emissions. Methane is emitted by natural sources such as wetlands, as well as human activities such as leakage from natural gas systems and the raising of livestock. Natural processes in soil and chemical reactions in the atmosphere help remove CH4 from the atmosphere. Methane's lifetime in the atmosphere is much shorter than carbon dioxide (CO2), but CH4 is more efficient at trapping radiation than CO2. Pound for pound, the comparative impact of CH4 on climate change is 25 times greater than CO2 over a 100-year period. Globally, over 60% of total CH4 emissions come from human activities. (1)

Landfills rank as the third-largest, human-related source of methane. (2) Officials of the Dubuque Metropolitan Landfill in 2011 chose to capture and flare (burn off) methane before the Environmental Protection Agency ordered it. (3)

Since installing a $1.3 million methane collection system, the Dubuque landfill witnessed a 30% reduction in its greenhouse gas emissions. The gas could be converted into electricity with estimates that between 800 and 1,000 homes could be powered. Officials, however, had not been able to negotiate a deal to sell the electricity to Maquoketa Valley Electrical Cooperative. Heat escaping the generators could also be piped to the landfill buildings to reduce the cost of heating. (4)

The City of Dubuque Water and Resources Recovery Center in 2015 used methane from its anaerobic digestion process to power turbines that generated enough electricity to replace 70 percent of the center's use. The center, however, produced more methane than it could use. Estimates placed the cost of producing compressed natural gas (CNG)at $5 million with estimated revenues of about $650,000. This assumed that more than 650,000 gallons were sold annually. In 2015 there were no fleets using CNG. (5)


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Source:

1. U. S. Environmental Protection Agency, Online: http://www.epa.gov/climatechange/ghgemissions/gases/ch4.html

2. Ibid.

3. Barton, Thomas J. "City Ahead of Curve on Landfill Emissions," Telegraph Herald, September 5, 2015, p. 1

4. Ibid.

5. Ibid. p. 2