Finally, biomass can be converted into biogas, either directly from the microalgal biomass or indirectly by the anaerobic digestion of the oilcakes. Various kinds of energies can thus be produced, and the perimeters of the study could be different. Methane potential strongly varies depending on the species composition and degradability (Sialve et al., 2009). In the con­sidered studies, it ranges from 0.262 (Collet et al., 2011) to 0.800 m3CH4 kgDM-1 (Brentner et al., 2011). It should be noted that this last value is higher than the theoretical maximum value for Scenedesmus (Sialve et al., 2009). Energy consumption of anaerobic digesters is usu­ally ignored. It is regrettable, since long hydraulic retention times required to digest low bio­degradable materials (from 10 to 40 days) represent a significant energy effort for mixing and heating. Heat consumption is estimated at 2.45 MJ kgDM in Collet et al. (2011), and electricity consumption is estimated at 0..47 MJ kgDM in Brentner et al. (2011) and 0.39 MJ kgDM in Collet et al. (2011).