Waste is deprived of oxygen and ferments, producing biogas as it decomposes. Once recycled, this biogas can replace fossil fuels to produce electricity, heat and even biofuel, thereby meeting Veolia's carbon neutrality objectives, while at the same time working towards ecological transformation.
What is biogas?
Biogas is a gas produced by the biological decomposition of organic matter in the absence of oxygen, a process known as anaerobic digestion or methanisation. It is mainly composed of methane (CH₄) and carbon dioxide (CO₂), with small quantities of other components (nitrogen, hydrogen, or hydrogen sulphide and water vapour). The organic matter used to produce biogas can come from a variety of sources, such as agricultural waste, food waste, wastewater or organic industrial waste. The biogas production process is carried out in facilities called anaerobic digesters, where micro-organisms break down the organic matter to produce gas.
Biogas is considered a renewable energy source, as it uses organic waste to produce methane, a fuel that can be used to generate electricity, heat homes or run vehicles. As well as providing a source of energy, anaerobic digestion also reduces the amount of organic waste, thereby contributing to sustainable waste management.
Through methanisation, non-recyclable waste becomes a source of renewable energy. The biogas produced (65-70% of which is methane and CO2) is captured in anaerobic digesters and then burnt to produce heat or electricity, or both, using a cogeneration system. Finally, it can also be purified to extract the methane: biomethane, a renewable gas, captured in this way can be injected into natural gas networks or used as a fuel (bioGNV). Methane, a greenhouse gas whose warming power is 28 times greater than that of CO2, makes it possible to capture and generate local, low-carbon and sustainable energy.
The proportion of Russian gas that could be replaced if we equipped all wastewater treatment plants and landfills in France to produce biogas by 2027.
As a major player in this sector, Veolia offers an integrated approach that meets local needs. The Group's approach brings together all the parameters needed to achieve the ambitious objectives of carbon neutrality and local renewable energy production. Making biogas from landfill sites requires an efficient collection and pre-treatment system, generally consisting of a network needed to recover and recycle the methane, and an electricity production unit made up of gas turbine generators with capacities that vary according to the size of the site.
Near Arras, the Artois Compost site is an emblematic example of this. It recycles organic waste from agriculture, the food industry, local authorities and supermarkets. It generates around 3.5 million m3 of biogas a year. The 25,000 tonnes of waste processed generate 8,000 MWh of electricity, equivalent to the annual consumption of 2,700 households. The biomass recovered prevents the emission of 2,000 tonnes of CO2 equivalent per year. Lastly, the organic matter not degraded during the methanisation process (7,000 tonnes a year) is reused as compost by local farmers.
The Sofia wastewater treatment plant in Bulgaria, managed by Veolia, is successfully demonstrating the feasibility of positive energy wastewater treatment plants. By harnessing the energy potential of sludge through biogas recovery, the plant exceeded its energy needs in 2018, generating a surplus of energy equivalent to 23% of its total consumption
This remarkable achievement places the Sofia station among Europe's pioneers in the field of positive energy. The surplus energy was intelligently fed back into the public grid, underlining the crucial role of wastewater treatment plants in the production and distribution of clean, renewable energy.
Methanisation and biogas production are innovative and sustainable solutions for managing organic waste and producing renewable energy. These processes make a significant contribution to the transition to a circular economy and to reducing greenhouse gas emissions. Methanisation, through anaerobic digestion, enables the efficient transformation of organic waste into biogas, which can be used as a versatile source of energy.
Initiatives such as the Sofia wastewater treatment plant in Bulgaria demonstrate the economic and environmental viability of these practices by generating surplus energy. By integrating these technologies more widely, we can aspire to more sustainable waste management, a reduction in our carbon footprint, and the optimal exploitation of organic resources to meet our energy needs.