Composition chimique et valorisation énergétique des biomasses végétales

Our research comes within the scope of plant biomasses production as a source of cellulose and hemicelluloses to be used to produce biofuel. The selection of the most suitable plant species to be converted into biofuel requires a good knowledge of their chemical composition and their suitability to be converted into biomethane or into bioethanol by fermentation, or to be used as solid fuel. We have developed an analytical method to quantify cellulose and hemicelluloses. This method is appropriate for the field of plant biomasses conversion into biofuel. It is based on a neutral detergent extraction which extracts interfering components of the biomass (Neutral Detergent Extraction), on an acid hydrolysis (Sulfuric Acid Hydrolysis) of cellulose and hemicelluloses and an analysis by a versatile technique (Liquid Chromatography - Charged Aerosol Detector) of the released monosaccharides. We have shown that this method (NDE-SAH-LC-CAD) quantifies cellulose, hemicelluloses and the composition of hemicelluloses with a high degree of accuracy. By the analyses of many biomasses, we found that the diversity of their chemical composition can be structured in groups of biomasses not only presenting similar properties and fiber contents, but also presenting common phylogenetic origins. To reduce the analytical costs, our approach has allowed us to select three commonly analyzed parameters (contents of cellulose, hemicelluloses and mineral compounds) as sufficient to predict the suitabilities of the different biomass to be converted into biofuel. Finally, it appears that productivity of gross energy per hectare depends primarily on the dry matter productivity of crops, rather than the evolution of their chemical composition during their growth.