Scientists Question EPA Estimates of Greenhouse Gas Emissions (from manure lagoons)

[OKIsItJustMe]

https://www.agronomy.org/news-media/releases/2010/0624/384/

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Contact: Sara Uttech, American Society of Agronomy, 608-268-4948, [email protected]

Scientists Question EPA Estimates of Greenhouse Gas Emissions

Anaerobic manure treatment lagoons may release more methane than current rules allow

MADISON, WI, June, 2010 – The approach the U.S. Environmental Protection Agency (EPA) uses to estimate greenhouse gas emissions from agricultural anaerobic lagoons that treat manure contains errors and may underestimate methane emissions by up to 65%, according to scientists from the University of Missouri.Anaerobic lagoons treat manure on some animal feeding operations prior to application to crops as a fertilizer. Methane, one byproduct of the treatment process, has 21 times the warming potential of carbon dioxide.

A 2007 U.S. Supreme Court ruling mandated the EPA consider greenhouse gases a pollutant. This led the EPA in 2009 to approve greenhouse gas reporting requirements for any facility that annually releases 25,000 metric tons or more of carbon dioxide equivalents to the atmosphere. The objective of these reporting requirements is to quantify emissions as a first step towards developing strategies to reduce greenhouse gas losses.

Direct measurements of methane emissions from anaerobic lagoons are technically difficult and very expensive, so the EPA adopted a calculation method to estimate methane emissions from anaerobic digesters. They relied on the method used by the International Panel on Climate Change (IPCC) in their 2006 worldwide estimate of greenhouse inventories.

An interdisciplinary team of scientists from the University of Missouri evaluated the EPA and IPCC approach to estimate greenhouse emissions from anaerobic lagoons. They reported the results of their analysis in the May-June 2010 issue of Journal of Environmental Quality, published by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America.

The team documented errors in the approach, which the EPA and IPCC adapted from a method used to estimate methane production from anaerobic digesters. A literature review of the performance of uncovered anaerobic lagoons indicated that there are important difference between anaerobic lagoons and anaerobic digesters that were not accounted for in the EPA and IPCC approach. They found that uncovered anaerobic lagoons were more efficient at converting waste to methane than predicted using literature based on digesters. The team also found mistakes the equations that the EPA and IPCC used.

John Lory, a member of the team that reviewed the EPA rule, said “Our calculated estimates of methane emissions from anaerobic lagoons indicated that the EPA approach could substantially underestimate methane emissions from these facilities, perhaps by as much as 65%.”

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[HillbillyBob]

1. I saw on some program where they connected the digester

up to a tank capturing the methane for reuse as fuel. A 3000 gallon unit did not produce all that much, as it was more of an experiment.

Some landfills are collecting the gas can't the same be done for these lagoons? At least until we remake our agriculture practices back to smaller numbers, not crowded in feed lots.

[OKIsItJustMe]

2. A number of farms use "BioGas" from digesters to generate electricity

Individual farms have been doing it for decades.

http://www.green-trust.org/2000/biofuel/methanedigestion2.htm

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Electricity from Manure Gases

Reprinted by special permission from the May, 1963 FARM JOURNAL


Make electricity: from hog manure? You're kidding! No, honest... I've just visited a farm where they're doing it. The owner is Dr. George W. Groth, Jr., who maintains 1,000 hogs in confinement on, his ranch in San Diego County, Calif. They make the 10-kilowatt generator hum by capping a liquid manure pit -- to trap the "sewer" gas -- and tying it to a gas engine. "There's just about the right amount of electricity to pump our water and run the heat lamps for the baby pigs," says Dr. Groth. As the system stands, Groth has right at $2,000 invested, including labor and the $800 he shelled out for a war-surplus generator. Converting the generator to "hog power" was simple. All it took was a natural gas carburetor plus a frill or two to increase efficiency. For example, hot water from the engine's cooling system circulates through 300 feet of copper tubing coiled inside the liquid manure pit. It maintains a 90° to 100° temperature in the pit. "You get maximum 'digestion' of the manure at that temperature," says Groth. A small pump which runs off the fan belt pulley circulates the radiator water.

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Although Dr. Groth's hog manure power plant may be the first one in this country, the idea isn't brand new. Similar systems have been tried on such fuel short continents as Asia and Africa.

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