Life cycle assessment of hemp hurds use in second generation ethanol production

Resource depletion, climate change and environmental pollution are priority topics in international environmental policy. The use of renewable resources for energy production is an interesting alternative to fossil fuels. Lignocellulosic biomass as a feedstock to produce ethanol may replace petrol as a transport fuel. A comprehensive Life Cycle Assessment was conducted on ethanol produced from hemp hurds (a by-product from dedicated fibre crops) in an enzymatic hydrolysis process that converts lignocellulosic biomass into ethanol. The environmental performance of two ethanol fuel blends, E10 and E85, in a flexi fuel vehicle was analyzed and compared. The environmental impact was determined by selecting two different allocation approaches (mass and economic allocation). A sensitivity analysis was conducted and four scenarios were evaluated, involving different allocation coefficients, taking into account market prices for agricultural products and the production volume of each product. The results show that ethanol-based fuels can offer improved environmental performance in impact categories such as global warming, as well as a decrease in energy resources based on fossil fuels. However, the use of petrol is the best option in terms of other impact categories, such as photochemical oxidants formation, acidification and eutrophication. The choice of allocation approach significantly affects the environmental performance and influences the question which fuel (E10 or E85) has smaller environmental impacts.