How does anaerobic digestion contribute to low-carbon transitions in agriculture?
First of all, the digestate made it possible to reduce the use of chemical fertilizers by 30 to 50% per year. At the same time, the root system of intermediate energy crops remains in the soil. They thus contribute to increasing carbon storage. Finally, methanization captures the gases that contribute to global warming from livestock effluent. This has been particularly reinforced since the 2020 regulations, which strongly encourage the integration of these effluents.
Where are the margins for progress today?
I identify three levers for strengthening this contribution. First of all, the production of renewable electricity, via solar panels, can be developed on site for self-consumption purposes. In addition, the valorization of biogas, particularly as fuel for agricultural equipment, is now favored. It is also experiencing renewed interest in the perspective of potential taxation of GNR. Moreover, a supplementary remuneration system is being studied for BioNGV use. The third way concerns the optimization of units to maximize their efficiency and limit gas emissions during storage. The rules are becoming clearer, from cultivation decrees to the spreading of digestate. They contribute to the low-carbon transition of the sector. As well as the RED* II and III Directives.
Carbon capture is one of these avenues. What are the issues ?
The use of bio-CO2 from methanization is today marginal and limited to a few greenhouse market gardeners in Brittany and Normandy.
The price of CO2, mainly of fossil origin, has exploded along with that of energy. Thus, Bio-CO2, that is to say of biological origin, is today the subject of economic interest which is added to its contribution to decarbonization. The main potential customers are greenhouse growers and the food industry for the carbonation of drinks.
Concretely, the opportunities and constraints will be specific to each unit because the cost of transport will be decisive. GRDF has therefore set up a guide and an online calculator. 21 studies are also underway at the unit or territorial level. For GRDF, the challenge of this capture is to consolidate the economic interest of methanization. It contributes to the decarbonization of the network we manage and to France’s energy sovereignty.
In November, Hervé Morin, president of the Normandy region, suspended his community’s support for methanization projects on the grounds of speculation on the price of certain crops, particularly corn. What do you think ?
Just like the Normandy Region, GRDF supports an exemplary sector. To our knowledge, the use of food crops in methanization is around 6%, well below the regulatory 15%. If there are abuses, it is natural that the Region wants to combat them. We remain one of the main partners of the Métha Plan to promote methanization in Normandy, to achieve 20% green gas in the networks in 2030, and 100% in 2050.
Claire Guyon-Maite
* European directives on the sustainability of bioenergy (RED II) and on the promotion of energy produced from renewable sources (RED III).
