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.

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.

  1. 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.
  2. 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.
  3. 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

Biogas Utilization

Engine-generator Sets

Fuel Cells

Related Resources

Biogas Cleanup

Hydrogen Sulfide Removal from Biogas

Biogas Upgrading

Archived Resources