Energy is more than ever a crucial issue for future generations, and natural gas is a major asset in the energy mix. According to the United Nations Sustainable Development Goals, alternative energy solutions for the future are required: GRDF is convinced of the need to move away from a linear approach based on fossil fuels to a circular economy in which organic waste is converted into renewable gas. The anaerobic digestion process is the most mature technology for producing green gas. More and more anaerobic digestion plants are being constructed in France to convert sewage and organic waste into biomethane. GRDF actively supports the development of these projects. 

At a time when we are trying to minimize the depletion of the earth’s resources, renewable sources of energy are crucial for ensuring the sustainability of our societies. 

By reducing greenhouse gases, improving waste management, preserving soil quality and water tables, and creating jobs, biomethane production plays a key role in the development of the local circular economy, where waste is converted into renewable resources, including energy.

How does anaerobic digestion work? 

In the anaerobic digestion process, all organic waste, such as household waste, agricultural and agri-food industry effluents, sludge from wastewater treatment plants and non-hazardous organic waste, are decomposed by micro-organisms. The anaerobic digestion of organic matter produces biogas that can be upgraded into biomethane in order to reach the same quality as natural gas. 

More concretely, organic waste is sorted, prepared and placed in an anaerobic digester, where it is mixed and heated. During this fermentation process, bacteria convert the carbon part of the waste into biogas. Once odorized for safety reasons and after an automatic analysis of its quality by GRDF, the biogas is called biomethane and it can now be injected into the gas distribution network.

Find more about the lifecycle analysis of the biomethane

Uses of biomethane include heating, cooking, hot water production and mobility (where it is known as bio-NGV). It is a perfect replacement for natural gas for these uses, as both comply with the same standards of quality. Local authorities, manufacturers and farmers are therefore embarking on these projects to produce and inject biomethane as an alternative energy solution.

The matter remaining as residue after the anaerobic digestion process has occurred is known as digestate. It is extremely rich in nutrients and is frequently used as fertilizer by farmers in the vicinity of the anaerobic digestion plant as a replacement for chemical fertilizers. As in most cases local farmers are responsible for providing the manure and biomass used in the feedstock, this is a textbook example of the circular economy working to everyone’s advantage !

Biomethane: what is the outlook? 

In April 2020, there were 118 biomethane injection plants injecting into the GRDF gas network in France, and 900 projects for new anaerobic digestion and biomethane injection facilities have been identified throughout the country. This reflects our target for biomethane injection in France, which is to vastly increase the maximum capacity from 1,320 GWh in 2019 to 12 TWh by 2023. 

Taking all French distribution networks into account, 2019 saw the number of biomethane injection sites commissioned in France rise by 62%, with 123 in all. The total number of projects recorded stands at 1,085, representing total capacity of 24 TWh/year (which is 10 TWh more than at the end of 2018). This corresponds to the average annual consumption of 106,000 buses or lorries running on Bio-NGV or 3.6 million new gas-heated housing units.

ADEME (the French Environment and Energy Management Agency) forecasts that there will be up to 1,400 sites injecting biomethane into the network in France by 2030, with biomethane accounting for 16% of the gas in the distribution network, meaning the benefits of natural gas as a source of energy can be combined with a significantly lower carbon footprint.

By 2050, 73% of the gas circulating in the distribution grid could be green gas, according to GRDF’s best-case scenario (ADEME puts the figure at 56%).

Alongside anaerobic digestion, pyro-gasification is a highly promising technology that uses a thermochemical reaction to convert dry biomass (organic waste matter) into several biogases, including methane and hydrogen. Demonstrator and pilot facilities are currently fine-tuning the process, which will contribute significantly to biogas injections into the network in the next few years. 

Meanwhile, Power-to-Gas (or P2G) technology uses the electrolysis of water to convert electrical energy into hydrogen, which can either be injected into the gas distribution network directly or further converted into synthetic methane through combination with CO2.

GRDF and the biomethane industry

As a player with a vital role in the gas chain, GRDF is committed to transforming the gas distribution network into an effective tool for the energy transition. The company works on a daily basis to develop solutions to ensure that the gas networks have adequate capacity to accommodate renewable energies. Additionally, GRDF acts to promote the injection of biomethane into the network through its undoubted expertise in: 

• planning anaerobic digestion projects with producers and local authorities (dimension, grid connection), 
• ensuring the quality of gas before injection in the distribution network. 

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