Submitted to: Symposium Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 9/26/2008
Publication Date: 5/30/2009
Citation: Ro, K.S., Cantrell, K.B., Hunt, P.G. 2009. Livestock processing options [abstract]. In: Proceedings of the Engineering Conference International Workshop on Defining Issues in Biofuels Research and Development, August 3-7, 2008, Calabria, Italy.
Technical Abstract: According to the recent study jointly sponsored by the United States (U.S.) Department of Agriculture and Department of Energy, U.S. agricultural lands currently have 35 million dry tons of available, sustainable animal manure. Assuming an average high heat value of about 13.4 MJ/kgTS for various animal manures, an efficiency of 15% for extracting useful energy, and an energy value of about $100 per barrel of oil equivalent, this sustainable animal manure would provide energy with an approximate worth of one billion U.S. dollars per year. . In this breakout session presentation, two thermo-chemical processing options are introduced to extract bioenergy from wastes especially from livestock wastes; wet gasification and carbonization. Wet gasifying or catalytic hydrothermal processing swine manure would produce energy comparable to combusting the same amount of brown coal. The costs of a conceptual first generation wet gasification manure management system for a model swine farm were found to be significantly higher than that of traditional anaerobic lagoon systems. However, there are many significant environmental advantages of the wet gasification that have not yet assigned monetary values: 1) removing oxygen demanding wastes, estrogens, and odorous compounds; 2) achieving total pathogen kills; 3) recovering most of nitrogen as ammonia, which could be used as a fertilizer; and 4) producing relatively clean water that, after minimal treatment, could be recycled as a livestock drinking water. One of the biggest challenges for this processing option is development of robust, cost-effective catalysts. Carbonizing dry livestock wastes such as poultry litter would produce valuable solid product--bio-char. Bio-char can be used as a cooking fuel, feedstock to existing coal firing power plants, and converted into a value-added activated carbon. Bio-char can also be used as a soil amendment to improve soil fertility. Preliminary bio-char soil application research results showed that bio-char improved soil quality, reduced leaching of nutrients, and increased soil organic carbon. In addition, the fixed carbon of the bio-char is quite recalcitrant and may be qualified for future carbon credit, which would bring additional revenue to farmers. For the carbonization process, developing energy efficient, air pollution free, and high yield carbonizing processes to generate bio-char with tailored qualities (“designer charcoal”) is the major engineering challenge.