Life Cycle Assessment of New Willow Cultivars Grown as Feedstock for Integrated Biorefineries

The fossil fuel resources which power the chemical and energy industries are shrinking or becoming increasingly expensive. Moreover, their excavation and consumption have a negative impact on the environment, including global warming. For these reasons, new, cleaner, resources are being sought to replace them, such as lignocellulosic biomass. The aim of this study was to determine the environmental impact of the production of seven new cultivars of willow grown in a commercial plantation for use in an integrated biorefinery. The characteristics of the production and transport of 1 tonne of dry willow chips for the minimum (cultivar UWM 155), maximum (cultivar UWM 006) and average yield have shown that the cultivar with the lowest yield has the highest impact on the environment for all the selected categories of impact (CML 2 baseline 2000 method). For the average yield across all the cultivars, at a transportation distance of 25 km, this study found a high environmental impact of mineral NPK fertilisation, biomass harvest and road transport. The stage of normalisation for the average yield showed that freshwater toxicity had the greatest impact on the environment of all the categories under study. The effect of the other categories was 22–76 % lower for abiotic depletion and global warming, respectively. GHG emission amounted to 36 kg CO₂ eq. per 1 Mg of dry willow chips transported for 25 km, and it increased with an increase in the transport distance by 24 and 71 % for 50 and 100 km, respectively. The lowest GHG emission per 1 Mg of dry chips was achieved for the production of the high-yielding biomass cultivars UWM 006 and UWM 043. Their chips could be transported for longer distances, i.e. 50 and 100 km, because their impact on global warming was much lower than the low-yielding cultivars UWM 155, Tur and UWM 035.