1. U.S. DOE, 2004, Available at: http://www.energy.gov/.
2. The PigSite.com, 2004, Available at: http://www.thepigsite.com/articles/914/manure-to-energy-the-utah-project.
3. USDA Agricultural Statistics, 2005, USDA National Agricultural Statistics Service, Washington DC (www.usda.gov).
4. L.J. Wang, Energy Efficiency and Management in Food Processing Facilities, Boca Raton, FL, 2008.
5. Biofuels;Demirbas,2008