Energy valorization of solid residue from steam distillation of aromatic shrubs

The interest for essential oils is increasing, alongside ongoing scientific research into distillation techniques. This process generates significant solid residue that could be revalorized as energy source. This study explores the energy recovery of the solid fraction produced during the distillation of three aromatic plants: Cistus ladanifer, Juniperus communis and Rosmarinus officinalis . Two conventional energy recovery technologies were considered and compared through an energy balance: solid biofuel production and biogas generation. In case of solid biofuels, the fractionation of biomass allowed for generation of three different qualities that meet the regulation standards of solid fuels, except for the dust fraction. According to the energy balance, the alternative use of these substrates for biogas production showed competitive production in case of Cistus ladanifer and Juniperus communis, while Rosmarinus officinalis biomass presented inhibition of the anaerobic digestion and null energy recovery . • Two energy generation routes from shrubs' distillation solid residue were studied. • Sieved and blown coarse/dust fractions yield high-quality biomass for combustion. • Anaerobic digestion demonstrated to be efficient for C. ladanifer and J. communis. • Biogas route in case of J. communis yields 45 % of the solid biofuel route • R. officinalis biomass hinders anaerobic digestion due to the inhibitors presence.