BE GREEN - MAKE BIOGAS
Gas is made from two processes where one is anaerobic digestion (AD) that is a series of processes in which microorganisms break down biodegradable material in the absence of oxygen. Another process is syngas can be produced from chemical reactions that happen in gasification and other thermal processes.
“WIND” TO POWER
AD is widely used to treat wastewater sludges and organic waste because it provides volume and mass reduction of the input material. As part of an integrated waste management system, anaerobic digestion reduces the emission of landfill gas into the atmosphere. Anaerobic digestion is a renewable energy source because the process produces a methane and carbon dioxide rich biogas suitable for energy production helping replace fossil fuels. Also, the nutrient-rich solids left after digestion can be used as fertiliser.
GREEN FARMS MAKE MORE MONEY
A third way of producing biogas is using farm waste and crops. The digestion process takes place in a warmed, sealed airless container (the digester) which creates the ideal conditions for the bacteria to ferment the organic material in oxygen-free conditions. The digestion tank needs to be warmed and mixed thoroughly to create the ideal conditions for the bacteria to convert organic matter into biogas (a mixture of carbon dioxide, methane and small amounts of other gases). There are two types of AD process:
Mesophilic digestion
The digester is heated to 30 - 45C° and the feedstock remains in the digester typically for 15-30 days. Mesophilic digestion tends to be more robust and tolerant than the thermophilic process, but gas production is less, larger digestion tanks are required and sanitisation, if required, is a separate process stage.
Thermophilic digestion
The digester is heated to 55C° and the residence time is typically 12-14 days. Thermophilic digestion systems offer higher methane production, faster throughput, better pathogen and virus ‘kill’, but require more expensive technology, greater energy input and a higher degree of operation and monitoring.
During this process 30-60% of the digestible solids are converted into biogas. The resulting gas contains some 60-70% methane and must be burned, and can be used to generate heat or electricity or both. Our CHP units can be configured to drive both the Mesophilic and Thermophilic digestion processes.
Click on the pictures of various Biogas CHP and Cogeneration plant below to enlarge.
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