STOCKACTIF

The rationale of this project of « smart storage » is to take advantage of the idle time between biomass harvesting and its utilization in a biorefinery : this time would be used for preparing biomass deconstruction via lignolytic bioprocesses. In other words, it would look as a kind of controlled ensiling fitted to the new utilization of biomass, namely its potentialities to be transformed in energy (bio-ethanol, biogas), in platform molecules (through white biotechnology of sugars coming from cellulose or hemicelluloses or as a source of phenolic compounds). This idea raises the question of the balance between the transformation of lignins and the losses of sugars during such a storage, but other issues are pregnant, like contamination or piloting the storage. This project deals with all of these by using solid state fermentation methodology and lignolytic fungus strains. The benefit would be at the same time energetical and environmental : for all kinds of biomass utilization, the two first steps in a factory (size reduction and pretreatment) are strong consumers of energy (grinding, cooking, steam explosion, ….) and possibly of chemical reactives (acid pretreatment, alkali pretreatment, organosolv pretreatment, …) which need to be filtered out and which deteriorate the environmental impacts. So a pre-conditioned biomass which would enable to lower, or to suppress, the pretreatment would be a noticeable benefit. In case of biogas production, a pre-conditioned biomass could gain wider possibilities of uses if its biodegradation kinetic fits with the classical substrates ones . In our approach, the essential difference in comparison to an industrial process is the time, which turned from hours to weeks. In fact, the background of the proposal is not new, as it is close to the « biopulping » process developed in papermaking industry around ten years ago, but the present project is designed to address new issues : - keep as max as possible the « utilization potential » of the biomass for ethanol (and so saccharification) and biogaz production - describe the operating parameters for piloting the storage, in order to be able to obtain a repeatable degree of transformation, whichever be the external perturbations, including the problem of contamination by sugars-consuming bacteria - set up the technico-economical balance between the possible loss of end use potential and the gain for pre-treatment and anaerobic digestion, particularly in terms of energy and environmental impacts - plan the use of this smart storage principle in a simple, low cost and realistic way by comparing a few pre-industrial solutions The research work is mainly cognitive, as the field to address is wide and it is necessary to handle the effects of several parameters to find an optimal solution. This work is managed through four main work-packages : - the screening for best suited fungus strain(s) and the choice of the level and the conditions of efficient inoculation methods - the description of the controlling parameters for solid state fermentation - the characterization of the products obtained regarding subsequent steps of process, and particularly grinding, bio-ethanol and biogas production - the influence of fungus preconditioning on the technico-economical and environmental balance. Thanks to the partnership of four industrial companies, the solutions will be tested at a pre-industrial scale. This step will also be an opportunity to test the prototype of an on-site device designed to sensor complex biological reactions, developed by a start-up company during this project. The private companies partnership is also a guarantee of moving the five academic research teams towards a robust and realistic solution for this smart storage principle.