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For the Public Health by Kari B. Fitzmorris, Sc.D.

Ag waste may prove good energy source

    For a long time, manure and other agricultural residuals have been, at best, a fertilizer, and at worst, a liability for farmers. That’s no longer the case. In today’s emerging world of reuse and bioenergy, farmers can transform that liability into an asset that benefits not only farmers, but everyone who seeks a cleaner and more sustainable environment. 
    While the world looks to ethanol made from corn to solve its energy problems, dairy, hog and poultry farmers can help create an even more efficient industrial process by using animal waste as an alternative raw material. A project currently underway in Hereford, Texas (http://www.seco.cpa.state.tx.us/re_biomass-manure.htm) is developing a $120 million ethanol plant that is projected to create an energy savings equivalent to 1,000 barrels of oil per day.  The plant will use technology to convert both animal waste and cotton gin waste into clean-burning biogas. The biogas will replace natural gas during the dry milling process used to create ethanol. 
    The use of animal waste as a precursor for biofuel is a well-known technology that is always being refined. The most common way to generate fuel from manure is through anaerobic digestion, where bacteria break down organic matter in an oxygen-free environment. In order for the resulting biogas to be captured and the oxygen-free environment to be maintained, the system must be contained and sealed.  Since the process takes place in a closed system, odors are significantly reduced.
    Once the biogas is captured, it is refined into usable electricity by a methane generator.  Different modifications of this basic system work better for different manure types. In Southeast Georgia’s warm climate, a plastic-lined lagoon with a sealed cover works well because we are not as concerned with heat loss. This entire process already takes place in most manure lagoons; the closed system is just a way to take advantage of emissions. 
    Based on the biogas production per 1000 pounds of animal, poultry manure is capable of producing the highest BTU/day, in the range of 43,000–55,000 (broilers produce more than layers).  Dairy manure is second with an average of 26,000 BTU/day.
    The cost of implementing a contained biogas recovery system can range from a few thousand dollars to millions. A Florida project, listed by EPA’s AgStar, was built in 2000 to serve a 500-head dairy at a cost of $150,000. 
    Since recovery systems are now considered a proactive way to treat animal waste, there are two main governmental information and funding sources: Environmental Protection Agency’s AgStar program (http://www.epa.gov/agstar/index.html) and USDA’s Small Business Innovative Research grant program and EQIP (Environmental Quality Incentives Program).  It’s important to note that this funding program is part of the new Farm Bill that is currently under review by the Senate.  This program and others relative to the production of bioenergy are projected to grow.
    If you would like further information about the process of turning agricultural waste into energy or about the 2008 Farm Bill, please contact me at (912) 681-0504 or kfitzmorris@georgiasouthern.edu.
    Kari Fitzmorris, Sc.D., is assistant professor of environmental health sciences in the Jiann-Ping Hsu College of Public Health at Georgia Southern University. She is Vice-chair of the Agriculture and Industrial Committee of the Water Environment Federation, a global organization.

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