The EMG pilot was initially foreseen to be installed at Eppeville site (Haut de France). However, due to operational constraints, a new location was decided in May 2024 with ENGIE BiOZ : Coevron Mayenne (Figure 1).
The new site is very similar to the initial one in Eppeville. It covers 2.6 ha surface and produces 2,000,000 m3 of CH4 per year. The plant has a capacity of 21 GWh, an amount of gas comparable to the consumption needs of 1,900 homes. Up to 220 Nm3/h are injected into the natural gas grid. Biogas is produced continuously in stirred tank reactors at mesophilic conditions from 30,000 tons/yr of agro-industrial and agricultural residues. The plant has a 9,000 m3 total digestion volume (2 main digesters of 4,500 m3 over 50 days of HRT).
The digestate storage capacity of the unit is 21,000 m3 for liquid digestate and 1,800 m3 for solid one. The digestate is valorized through land-spreading over 3,000 ha (21 farms).
Figure 1 : ENGIE BiOZ demo site : Coevron AD unit
In the preparation of the pilot, FAU partner finalized CFD modeling of the 1 chamber system aiming at facilitating design decisions on the stirring strategy.
Indeed the mixing behavior of the high viscous liquid digestate can be strongly influenced by the choice of a suitable stirrer, taking into account the internals such as electrodes or by changing the recirculation flow. CFD simulations results show that a combination of Rushton and hydrofoil geometries was the best suited for the 1 chamber reactor (Figure 2).
Stefanie Feilner (Friedrich Alexander University-FAU) presented these investigations of the single-chamber system using CFD simulations in a presentation at the 16th International Conference on sustainable energy & environmental protection SEEP 2024 in Vienna and won the best oral presentation award. The project team congratulates Stefanie for this very nice prize!
Figure 2 : CFD Simulations on the 1 chamber system
