VaLiCel: valorisation of (ligno-)cellulose residues and energy crops

Based on the estimated global annual production of biomass (1x1011 ton U+2248 2 ZJ ), theoretically plants could easily substitute for the annual 0.2 ZJ petroleum production. In only one decade, plant biomass could in the form of cellulose, hemicellulose, and lignin renew the 20 ZJ energy stored as conventional crude oil . Although the relatively high cost of both pretreatment and enzymes that catalyze cellulose hydrolysis [one-third of the cost of ethanol production from cellulose] still represents a major barrier to commercialization, cellulosic ethanol production is currently in the pilot plant stage, with more than 30 pilot plants being operated in both North-America and Europe. The process generally consists of a pretreatment step, a hydrolysis and a fermentation step. In these processes lignin is discharged as a byproduct that can be used to supply the process with energy. It is however generally believed that a successful bioenergy research policy should focus on biorefineries, co-producing transportation fuels, power, heat, added-value chemicals and materials from biomass. In the IWT TETRA [a grant program to stimulate innovation in Flemish companies through technology transfer] project VaLiCel, we have compared several pretreatment, hydrolysis and fermentation conditions using lignocellulosic residues (recycled paper pulp, loams & scutched short flax, wood (dust), grasses and agro-industrial waste) and dedicated energy crops (Miscanthus x giganteus, poplar and willow). The yield of fermentable sugars and ethanol is determined and compared. Ultimately, the aim is to know which lignocellulose waste is suited for complete saccharification to glucose and xylose and yields minor side products that are inhibitory to alcohol fermentation. From our results it is clear that by screening a collection of different biomass feedstocks, evaluating different pretreatment methods, screening a large set of yeast strains and optimizing the préculture and fermentation conditions, it is possible to produce second generation bio-ethanol in an economically viable way. First results of a case study will exemplify a possible integration strategy into existing industrial fuel producing plants. It is expected that the co-production of added-value products will lead to overall economic profitability in an integrated biorefinery process. In casu the valorisation of lignin -as a source for aromatic chemicals- can play a key role in the further development of lignocellulosic biomass conversion processes.