Life cycle assessment of pilot-scale wood fibre production using mechanical disc refining at different pressures

This paper assesses the environmental impact of pilot-scale wood fibre production across a range of refining pressures using energy monitoring at an individual component level. Under optimal refining conditions (8 bar refining pressure; 15 mu m plate gap width), electricity use accounted for 88% of greenhouse gas (GHG) emissions associated with the fibre production, and was the dominant input in almost all other impact categories. At an individual component level, the refiner, dryer fan and hot oil burner were the most significant parts of the process (representing 30, 20 and 16% of cradle-to-gate GHGs, respectively), while ancillary processes such as the air compressor (6.9%) and dust extraction (6.3%) also made notable contributions. The analysis suggests that energy efficiencies made with these key components may offer the best potential gains in terms of the environmental profile of pressurised refining, as long as these can be achieved without compromising yield or quality of the fibre produced.