Anaerobic digestion technology is a powerful tool for managing organic farm waste, particularly cow, swinr and chicken manure. Agricultural biogas is a methane based fuel gas resulting from the anaerobic digestion of animal wastes or the combination of animal wastes and agricultural products. It does not include gases from landfills, synthetic processes or wastewater treatment plants.
Organic matter is flushed or loaded into large lagoons (pits) or sealed containers where bacteria in the natural anaerobic digestion process produce biogas (typically 65 % methane and 35 % CO2). In many parts of the world, agricultural biogas is responsible for up to 10 % of greenhouse gases. The methane can be collected for consumption / destruction in a gas generator set to create electricity while enabling emissions credits.
Farms, making use of this technology have been able to manage their animal wastes and produce energy for sale, beyond what their farm operation uses. Collected biogas can be used for process heating, electrical generation, production of pipeline-quality methane and transportation fuel.
- swine farrowing / feeding;
- cattle feeding and milking;
- fow; brooder house / feeding;
- heat intensive applications, like greenhouses, heat for operation facilities, heat for improved digester operation, etc.
In typical agricultural biogas plant methane and CO2 generated during decomposition of organic wastes. The effluent can be heated to accelerate the process (38 °C or 56 °C) and therefore promoting faster decomposition. rarely will blowers are used to aerate effluent, which is not cost effective and can hold effluent for longer periods of time.
Main benefits of utilizing agricultural biogas in cogeneration systems:
- Production of electricity generated by agricultural biogas is environmentally safer than the electricity generated by fossil sources. Modern agriculture, especially the management of animal manure, is very polluting and responsible for very large amount of the CH4, N2O and NH3 emissions. In cogeneration plant, anaerobic digester reduces the damaging effects of methane, which as a greenhouse gas is 21 times more potent than carbon dioxide.
- Anaerobic digesters perform well at degrading the strength of organic wastes by reducing chemical oxygen demand. It helps to protect the health of aquatic ecosystems since fish and other aquatic life require a minimum level of dissolved oxygen for survival.
- Beneficial bacteria in the digester significantly reduce odor-causing compounds. Besides, flye eggs are killed during anaerobic digestion, reducing this disease-causing pest.
- In addition to the biogas produced, most of the organic nitrogen present in the manure is converted to ammonia, a fertilizer readily utilized by plants.
Biogas systems can be implemented in many configurations and need to be designed specifically for the site. System tanks and components can be made from a variety of materials, including steel, plastic, or concrete and can be built either above or below ground. Components made with copper or other non-corrosion resistant metals are subject to the hydrogen-sulphide corrosive effects of biogas and should be not used. The anaerobic process works best at specific warmer temperatures. In systems, where the waste is not warm, it must be preheated. Successful use of anaerobic digestion usually requires manure handling system in which manure is collected daily.