Complementary use of long and short hemp fibres for textile and second generation biofuels.

Hemp is a multifunctional crop widely known to provide good quality fibres for textile industry and bio-composites (e.g. interior carpeting of cars door). Machines for processing hemp fibres are lacking or absent, nonetheless recent studies [1] showed that one metre long cut stems can be easily utilized within a flax scutching line, thus making hemp a likely competing fibre crop in the near future. In fact, along with long fibres, a relevant amount of short fibres and shives can be obtained during scutching that, thanks to their high content of cellulose and hemicellulose, could be profitably processed for producing 2nd generation bioethanol. From this perspective, two hemp varieties, the Italian dioecious Fibranova and the French monoecious Futura75, were compared on the base of their productivity, suitability to industrial flax scutching line and potential bioethanol yield by the use of by-products. The biomass productivity was not significantly different between the two varieties (on average, 13.8 Mg ha-1). In contrast, Fibranova showed a slightly higher fibre content than Futura (33% and 31%), and above all a significant lower presence of long fibres (12%) than Futura 75 (16%). Short fibres showed an higher cellulose content (70%) with respect to shives (54.6%). The potential bioethanol yields by the use of co-products were 5.472 L ha-1 for Fibranova (113 GJ ha-1) and 5.165 L ha-1 for Futura75 (120 GJ ha-1).