As the price of electricity has been increasing in recent years, biogas has proven to be an interesting alternative, allowing for both green electricity and very affordable prices. Indeed, the waste methanisation technique offers many advantages such as the production of heat, fuel and electricity. But how is energy produced through this anaerobic digestion? Here is our answer!
What is anaerobic digestion?
Also called methanisation, anaerobic digestion is a natural phenomenon in which decomposable products or materials are broken down by bacteria acting in the absence of oxygen. Scientists call this process anaerobic fermentation. This procedure is very reliable because it produces biogas which is considered renewable energy and consists of up to 70% methane, carbon dioxide and compost. The latter can be used as a fertiliser, while the biogas can be transformed into fuel, heat, or electricity. This phenomenon of methanisation occurs naturally in marshes, where certain plant and animal matter decomposes and produces air bubbles at the surface.
How does methanisation produce energy?
Methanisation or methanation is a more or less complex process that consists of storing organic waste in a dedicated, hermetically sealed cylindrical tank. These tanks, otherwise known as digesters, reactors, or fermenters, operate at an ambient temperature of 35°C. Methanisation is triggered automatically by micro-organisms in the absence of air. Depending on the type, a modern reactor can produce up to 10 m3 of biogas per day for each cubic metre of waste introduced. The size and shape of the gas production units vary according to the need for thermal use. For instance, you can find a small digester of 100 m3 at a farmer’s site, while an unusual biogas plant can have up to 40 huge reactors.
Biogas can be used for the production of heat, electricity, or both at the same time. Professionals in the field also inject it into the gas network after removing unwanted impurities such as CO2. Some companies also use biogas to produce fuel for CNG or natural gas vehicles. Engineers in several European countries are currently developing innovative projects for the production of biogas fuel to facilitate public transport. Currently, many countries around the world have joined the race to install biogas plants.