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Accomplishments

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AgSTAR is one of EPA’s climate-protection partnership programs, which promotes investments in alternative energy technologies by encouraging the development and adoption of anaerobic digestion (AD) technology in the livestock sector. Since 2000, the use of biogas recovery systems with AD in the livestock sector has continued to increase, which has led to meaningful reductions in greenhouse gas emissions.

Office of Atmospheric Programs: Climate Protection Partnerships 2012 Annual ReportEPA climate partnerships are making steady progress reducing greenhouse gas emissions, decreasing wasted energy, and saving American families and businesses money.


Learn more about these programs, including AgSTAR, in the Office of Atmospheric Programs: Climate Protection Partnerships 2012 Annual Report (PDF) (48 pp, 4.5 MB)

AgSTAR Annual Emission Reductions (2000-2012)
Column chart showing the annual increase in greenhouse gas emissions reductions from 2000 through 2012.

Office of Atmospheric Programs: Climate Protection Partnerships 2012 Annual Report (PDF) (48 pp, 4.5 MB), page 22



2013 Use and Benefits of AD in the Livestock Sector

From its preliminary analysis, AgSTAR estimates that approximately 239 AD systems were operating at commercial livestock farms in the United States in 2013. Learn more about AD Projects.

In 2013, AD systems directly reduced emissions by an estimated 2.06 million metric tons of CO2 equivalent (MMTCO2e) and approximately 0.47 MMTCO2e was avoided, producing a total emission reduction of 2.53 MMTCO2e. To complement the Annual Report, the chart below distinguishes the portion of the total emissions that were directly reduced and the emissions avoided from the reduction in fossil fuel use.


Environmental and Energy Benefits

Greenhouse Gas Emission Reductions (2000-2013)
Column chart showing the annual increase in greenhouse gas emissions reductions from 2000 through 2013. In 2013, AD systems directly reduced emissions by an estimated 2.06 million metric tons of carbon dioxide equivalent and approximately 0.47 million metric tons of carbon dioxide equivalent was avoided, producing a total emission reduction of 2.53 million metric tons of carbon dioxide equivalent.

2013 Total = Estimated 2.53 MMTCO2e

AD systems reduce greenhouse gas (GHG) emissions in two ways. First, direct methane emissions are reduced by capturing and burning biogas that otherwise would escape into the atmosphere. Second, AD projects generate energy that displaces the use of fossil fuels, resulting in the avoidance of GHG emissions and other pollutants. In 2013, AD systems directly reduced emissions by an estimated 2.06 million metric tons of CO2 equivalent (MMTCO2e) and approximately 0.47 MMTCO2e was avoided, producing a total emission reduction of 2.53 MMTCO2e.

To be consistent with the Fourth Assessment Report of the Intergovernmental Panel on Climate Change (IPCC AR4)Exit EPA Disclaimer methodology, AgSTAR’s emission reduction calculations have been updated to reflect a global warming potential (GWP) of 25 for methane for 2013 and prior years.

Energy Generation (2000-2013)
Column chart showing the annual increase in the amount of energy produced by AD projects from 2000 through 2013. Approximately 840 million kilowatt hours equivalent of energy was generated by AD systems on livestock farms during 2013.

2013 Total = Approximately 840 million kilowatt hours (kWh) equivalent

AD systems generate usable energy each year by using biogas to generate electricity, as a boiler fuel for space or water heating, or for a variety of other uses. Approximately 840 million kilowatt hours (kWh) equivalent of energy was generated by AD systems on livestock farms during 2013.


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Visit the GHG Calculator

Greenhouse Gas Equivalencies

Understanding greenhouse gas emission reductions is challenging, so it helps to think of the environmental benefits in terms that are more relatable. Using EPA’s Greenhouse Gas Equivalencies Calculator, equivalencies are presented below for the total estimated emissions reductions from AD systems on livestock farms in 2013 (2.53 MMTCO2e).

CO2 emissions from one of the following:

More information 284,685,496 gallons of gasoline consumed
More information 2,717,508,056 pounds of coal burned
More information 33,492 tanker trucks’ worth of gasoline
More information 230,839 homes’ energy use for one year
More information 348,006 homes’ electricity use for one year
More information 13,566 railcars worth of coal burned
More information 105,416,667 propane cylinders used for home barbeques

Annual GHG emissions from one of the following:

More information 906,810 tons of waste sent to a landfill
More information 129,677 garbage trucks of waste recycled instead of landfilled



Carbon sequestered by one of the following:

More information 64,871,795 tree seedlings grown for 10 years
More information 2,073,770 acres of U.S. forests in one year
More information 19,535 acres of forests preserved from conversion to cropland in one year

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Anaerobic Digester System Designs and End Uses of Biogas

Operating AD System Designs in 2013
Pie chart of the designs of operating AD systems in 2013. 33 percent is complete mix. 32 percent is mixed plug flow. 14 percent is covered lagoon. 10 percent is horizontal plug flow. 2 percent is induced blanket reactor. All other designs make up 7 percent of the total. 2 percent of the total is unknown.

Number of AD systems in 2013 = 239

Operational AD systems use several types of technologies to generate power. Complete mix and mixed plug flow designs accounted for 65 percent of all operational AD systems in 2013.


Trends in AD System Designs (2000-2013)
Line chart showing trend of AD system designs from 2000 through 2013. In 2013, 78 projects were complete mix, 76 were mixed plug flow, 34 were covered lagoon, 23 were horizontal plu flow, and 5 were induced blanket reactor. All other known designs accounted for 18 projects and the design was unknown for 5 projects.

The number of projects operating in 2013 is shown in parentheses.

Complete mix and mixed plug flow systems continue to be the most common designs. AgSTAR anticipates that the use of complete mix designs will continue to expand as farms take advantage of opportunities offered through codigestion, which refers to the simultaneous anaerobic digestion of multiple organic wastes in one digester.

End Uses of Biogas in 2013
Pie chart of the end uses of the biogas captured by operating AD systems in 2013. 46 percent of projects use the biogas for combined heat and power. 40 percent generate electricity. 5 percent use the biogas as fuel for a boiler or furnace. 5 percent flare the gas full time. The remaining 4 percent of the total use the biogas for other purposes.

Number of AD systems in 2013 = 239

Captured biogas is used to generate electricity, as a fuel for boilers or furnaces, treated to create compressed natural gas, or for a combination of uses.


Trends in End Uses of Biogas (2000-2013)
Line chart showing the trend of biogas uses from 2000 through 2013. In 2013, 109 projects used biogas for combined heat and power, 95 generated electricity, 13 used biogas as fuel for boilers or furnaces, 12 flared the biogas full time, and 10 projects used biogas for other purposes.

The number of projects operating in 2013 is shown in parentheses.

Combined heat and power continues to be the most common use for biogas followed by electricity generation. Visit the projects page to access details about AD projects across the United States.

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