Results and Discussion Back http://www.westbioenergy.org/cattle/results.htm (15 <strong>of</strong> 15) [3/26/2003 8:52:58 AM]
Conclusions CONCLUSIONS AND SUGGESTIONS FOR FURTHER ACTIVITIES Beef cattle feedlots in the Texas panhandle produce more than 6 million beef cattle annually, and the manure from these feedlots represents a tremendous <strong>biogas</strong> energy potential. This project utilized laboratory and field experiments to evaluate <strong>biogas</strong> <strong>production</strong> from beef cattle manure scraped from open lots. The field project evaluated <strong>using</strong> landfill-type cells for producing <strong>biogas</strong> from beef cattle manure. In laboratory experiments where <strong>low</strong> density polyethylene (LDPE) containers were used as mini digesters, we discovered that the containers were too permeable to gases to obtain representative <strong>biogas</strong> <strong>production</strong> rates. In modified experiments, <strong>biogas</strong> <strong>production</strong> rates reached a maximum <strong>of</strong> 0.14 liters per gram VS at a wet basis <strong>moisture</strong> <strong>content</strong>s <strong>of</strong> 70%, which is <strong>low</strong>er than published values <strong>of</strong> about 0.3 liters per gram VS. In the field <strong>demonstration</strong> project, <strong>biogas</strong> was produced during a 12 week period in August through October. A total <strong>of</strong> 1,500 m 3 <strong>of</strong> <strong>biogas</strong> was produced at a rate <strong>of</strong> 0.10 liters per gram VS. While the results are promising, only producing <strong>biogas</strong> for 3 months out <strong>of</strong> the year severely limits the application <strong>of</strong> this method at beef cattle feedyards. A heated digester would produce <strong>biogas</strong> year-round, however, additional studies and engineering work are warranted to see if the landfill-cell method would be economically justifiable for use at beef cattle feedyards. REFERENCES Angelidaki, I. and B.K. Ahring. 1994 Anaerobic thermophilic digestion <strong>of</strong> manure at different ammonia leads: Effect <strong>of</strong> temperature. Water Research 28: 727-731. ASAE, 1999. Uniform terminology for rural waste management. ASAE Standard S292.5. American Society <strong>of</strong> Agricultural Engineers, St. Joseph, MI. Engler, Cady R. and Marshall J. McFarland. 1997. Dairy manure digestion research and <strong>demonstration</strong> project. In Proceedings <strong>of</strong> Workshop #1, Livestock Waste Streams: Energy and Environment. pp. 64-68. Texas Renewable Energy Industries Association:Austin, TX. Hansen, Kaare Hvid, Irini Angelidaki and Birgitte Kiger Ahring. 1998. Anaerobic digestion <strong>of</strong> swine manures: inhibition by ammonia. Water Research 32:5-12. Kottwitz, D.A. and D.D. Schulte. 1982. Tumble-mix anaerobic digestion <strong>of</strong> dry beef manure. ASAE Paper Presented at the 1982 Winter Meeting, American Society <strong>of</strong> Agricultural Engineers, St. Joseph, MI. Misra, Upama, Sonjay Singh, Amarika Singh, and G.N. Pandey. 1992. A new temperature controlled digester for anaerobic digestion for <strong>biogas</strong> <strong>production</strong>. Energy Conservation Management 33:983-986. Nalgene, 1999. Physical properties <strong>of</strong> Nalgene Labware, Internet Source. Parker, D.B., B.W. Auvermann, B.A. Stewart and C.A. Robinson. 1997. Agricultural energy consumption, http://www.westbioenergy.org/cattle/conclusions.htm (1 <strong>of</strong> 2) [3/26/2003 8:52:58 AM]