What is biogas?
Biogas consists primarily of methane (CH4) and carbon dioxide (CO2). The methane is a valuable product as it is an efficient energy carrier that has a wide range of uses. The CO2 produced is equivalent to the amount of CO2 captured when the biomass was created. Biogas is therefore a source of energy which is CO2 neutral and renewable.
How is biogas produced?
Biogas is produced whenever organic materials decompose in an anaerobic environment (environment without oxygen). Microorganisms and bacteria make the process happen and it is a natural process which occurs in many instances in nature. In a biogas plant this natural process is simply accelerated by creating the best possible conditions for the microorganisms and bacteria.
Biogas from what?
Basically any organic material can be used to produce biogas with some limitations, but typically manure, crops and industrial organic waste often coming from the food processing industry are used.
Benefits and advantages of biogas
• Production of high value green energy (electricity, heat, cooling)
• Reduction of greenhouse gas (GHG) emissions
• Reduction of nutrient loss and nitrogen washout from fields (manure processing plants)
• Reduction of pathogens
• Efficient use of organic by-products
• Reduction of odor emissions (manure processing plants)
• Highly efficient energy conversion of wet biomass
What is left?
It is not possible to decompose all of the biomass which is being fed into the biogas plant. As a result, the process leaves a residue. This residue can be used as a substitute for mineral fertilizer.
What can biogas be used for?
The biogas plant is capable of converting the biogas into energy which can be used. Typically this is done using a gas-engine that generates electrical power and heat. The power can be fed into the grid and the heat can be used locally. Alternatively, the biogas can also be refined to natural gas quality, which can be fed into the natural gas grid or used as transport fuel. Vehicles running on compressed natural gas (CNG) are available on the market today from the major car/truck manufacturers.