Environmental assessment of flax straw production for non-wood pulp mills

Nowadays, there is an increasing interest for using non-woody fibres as raw materials for production of paper´s pulp. The present work aims to identify and quantify the environmental impacts associated with the production of flax fibres, through 3-year field experiment, carried out in Bologna and Pisa representative of the pedoclimatic characteristics of central Italy. Life Cycle Impact of “a one ton of fibre ready to be processed in a pulp mill” was assessed taking into account: farming, straw process (drying, scutching and baling) and transport. Inventory data for agricultural inputs and outputs were obtained directly from field experimentation and from bibliographic data about heat, transport and electricity consumption on straw processing. An economic allocation approach to assign impacts within flax seed and processed straw has been used. The CML baseline 2000 methodology was selected to quantify the potential environmental impact associated to the crops. Specifically, global warming (GWP), acidification (AP), eutrophication (EP) and photochemical oxidant formation (POP) were evaluated together with energy use (EU). Major impacts contribution arise from fertilizers use and straw processing. Cultivation phase of flax fibre at Pisa reported higher values (approximately 3 times greater) for all the impact categories. The lower impact in the flax cultivation scenario at Bologna was due to no use of mineral fertilizer and the higher flax-straw yield. It resulted also a strong reduction of the impacts with respect to those of hemp pulp in Spain as well as to the impacts of the conventional wood-pulp reported in Simapro. Furthermore, LCA tool aided to identify the materials and process that most affected the impacts: fertilizers use, diesel consumption and straw processing were identified as hot spots in both crops. Finally, non-wood pulp derived from Bologna´s Flax straw represents an opportunity to replace conventional wood pulp in Italian paper industry.