Biogas
Anaerobic digestion produced biogas is an environmentally friendly, renewable fuel. Before use, it is important to clean or upgrade the gas to increase its heating value and to make it functional in some gas appliances such as engines and boilers.
Biogas includes methane, carbon dioxide, and other trace gases. The production of biogas happens when manure is kept in an anaerobic environment. The produced methane can be utilized right away to create heat or electricity, or go through a cleanup process to create renewable natural gas for the grid or fuel.
- A Technical Reference Guide for Dairy-Derived Biogas Production, Treatment, and Utilization - Tim Shelford, Curt Gooch, Abhinav Choudhury, and Stephanie Lansing, January 2019
- Characterization of Dairy-Derived Biogas and Biogas Processing - Norm Scott, Steven Zicari, Kelly Saikkonen, and Kimberly Bothi, July 2006
Biogas Production
Biogas production relies on anaerobic bacteria to transform manure and other organic material into biogas and liquid effluent. There are three stages to the process of biogas production.
- Liquefaction
Liquefying bacteria convert insoluble, fibrous materials such as carbohydrates, fats, and proteins into soluble substances. Water, some fibrous material, and other inorganic material also can accumulate in the digester or pass through the digester unchanged. Undigested materials make up the low-odor, liquefied effluent. - Acid Production
Acid-forming bacteria convert the soluble organic matter into volatile acids--the organic acids that can cause odor production from stored liquid manure. - Biogas Production
Methane-forming bacteria convert those volatile acids into biogas--a gas composed of about 60 percent methane, 40 percent carbon dioxide, and trace amounts of water vapor, hydrogen sulfide, and ammonia. Not all volatile acids and soluble organic compounds are converted to biogas; some become part of the effluent.
Biogas Resources
- Methods for Kinetic Analysis of Methane Fermentation in High Solids Biomass Digesters - Brian Richards, Robert Cummings, Thomas White, and William Jewell, 1991
- Biogas Processing and Utilization - Norm Scott, Kim Bothi, Bruce Roloson, 2004
- A Model of Solar Energy Utilization in the Anaerobic Digestion of Cattle Manure - Hamed M. El-mashad, Wilko K.P. Van Loon, and Grietje Zeeman, 2005
- High Rate Low Solids Methane Fermentation of Sorghum Corn and Cellulose - Brian K. Richards, Robert J. Cummings, and William J. Jewell, 1991
- Starvation and Overfeeding Stress on Microbial Activities in High-Solids High-Yield Methanogenic Digesters - David B. Hedrick, Arpad Vass, Brian K. Richards, William J. Jewell, James B. Guckert, and David C. White, 1991
- In Situ Methane Enrichment in Methanogenic Energy Crop Digesters - Brian K. Richards, Frederick G. Herndon, William J. Jewell, Robert J. Cummings, and Thomas E. White, 1994