From May 2021, the plant built by AgriKomp injects biomethane into the transport network at a rate of 350-400 Nm3/h injected from their first week. The plant, with an investment of 8,5 million euros, has been promoted by five farmers and ranchers from the French department of Oise and has an annual production of 24 GWh that they sell to Dalkia. It is located in the city of Saint-Crépin-Ibouvillers, next to the A16, along which the GTRgaz transport network runs.
SAS Chemin du Roi uses substrates such as beet pulp, grain silo bottoms, catch crop silage, but also livestock effluents such as cattle and horse slurry and manure, as well as food industry waste. The total amounts to between 30 and 35 thousand tons of annual consumption. The maximum price they can pay for each raw material is estimated at one third of the economic value generated by each of them., in fact they have a simple but fast and efficient laboratory to know the energy production in advance. These materials are stored in the plant in two 100 m3 pits for liquids and in 6.000 m2 flat silos for solids and are incorporated into the system through two pusher bottom hoppers.
The plant methanizes in two digesters and a 2.500m3 post-digester.. The stirring system is designed for substrates with high mechanical stress and generates currents in different directions that allow homogeneous mixing of the substrate and prevent the formation of a surface layer. Its energy consumption is low and maintenance is simple since all the main parts are located outside the tanks. The temperature is maintained by combustion of biogas in a specific boiler. Biogas storage is carried out under double PVC membranes.
Three 1.000 m3 gasholders ensure a production autonomy of approximately six hours. Biogas is purified by membranes, with a maximum flow rate of 750 Nm3/hour. Before being sent to the injection module, it is compressed to a pressure of 50 bar so that it is accepted into the transport network. Energy efficiency is key in this plant, since it is not limited at any time when injecting into the transport network, sometimes it reduces the injection depending on the current electrical cost, which is around 30.000 euros per month. .
Storage of the digestate is carried out with phase separation. Two ponds totaling 11.000 m3 store the liquid part, providing stock for about six months of production. The solid part, about 6.500 tons per year, is stored in an area of 860 m², providing storage for four months of production. The recreation plan includes 2.000 hectares at a maximum distance of 5 km from the plant. Regarding the costs of slurry, in 2023 they were receiving it at €3,5/t and spreading it at €4,5/t in order to offset transportation costs.
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