Energy Use in the Production of Flax Fiber for the Reinforcement of Composites

A comparative quantitative life cycle assessment (LCA) should consider the eight environmental impact classification factors listed in ISO/TR 14047:2003. This paper reports on the energy requirement for production of flax fibers to be used as reinforcement in composite materials. Data are compiled from a number of published sources. Only 5% of the harvested plant mass is converted into long fibers, while the other 95% could be regarded as waste; the respective coproducts (short fiber for paper manufacture, shives for animal bedding, and dust for fuel) can be collected, processed, packaged, and sold. The analysis here assumes that these coproducts are disposed of at a cost that covers the postseparation handling and hence they are not included in the flax burdens. The analysis suggests that sliver (post-carding fiber) has an embodied energy comparable to glass fiber reinforcement mat at approximately 55 GJ/tonne. Spinning fibers to produce yarn for weaving dominates the embodied energy. In the event that best agricultural practice is taken into account, and that some energy usage is apportioned to coproduct, then the claim that flax is a sustainable green alternative may be justified for random mat reinforcement. If the fiber is spun to yarn, then the embodied energy for flax exceeds that of the glass fiber equivalent.