Optimisation de la production d’éthanol de seconde génération et de pellets à partir de résidus forestiers

Following the Paris Conference (COP21), Canada (and especially Quebec) have made ambitious commitments to reduce their greenhouse gas (GHG) emissions 37.5% below 1990 levels before 2030. With a Canadian population concentrated in urban centers and a large territory, liquid biofuels are an unavoidable option to achieve this goal, since electrical vehicles still have energy storage issues. The proposed project aims at producing ethanol from forest residues and more specifically softwood bark by acid hydrolysis of cellulose in two stages. The NSERC part of the project will focus on the hydrolysis process developed at the Biomass Technology Laboratory (LBT) by Professor Jean-Michel Lavoie’s team, for which a pilot was designed. The process will be optimized for different forest residues (chips, sawdust, bark, etc.). Mass balances and energy consumption will be evaluated. In parallel, the batch process technology implemented for the pilot will be converted into a continuous process and then at industrial scale. Special considerations will be made for the bark for which the hydrolysis process is particularly suitable. Indeed, the use of bark for the production of ethanol is often put aside because of the high extractive content. Extractives such as terpenes, resins and tannins inhibit the enzymatic hydrolysis as well as the fermentation. Nevertheless, the preliminary results showed that the hydrolysis process developed at the BTL allows recovering both the reactant and the carbohydrate produced from lignocellulosic biomass. In Québec, bark is an abundant, undervalued and therefore inexpensive resource, while other forest residues suffer from competition for the production of wood pellets or the pulp and wood-based panel. In 2013, bark production in Québec was 2 263 000 tonnes and over 11 500 000 tonnes in Canada. In addition, the residues obtained at the end of the process consist mainly of lignin, which will further be transformed into 3rd generation pellets for the production of energy also allowing making cogeneration and thus reducing the energy costs of the process while increasing the profitability by an extra added value. The tests already carried out on the barks highlight an important calorific value of these residues allowing the production of granules of quality, with yields of the fermentation of more than 99%. This research project will cover the development of fermentation techniques, purification of produced ethanol as well as the production of wood pellets and their characterization.