Additives in wood pellet produciton - A pilot-scale study of binding agent usage

Finland currently has tremendous enthusiasm to increase decentralised pellet production alongside of large-scale factories. The aim of research is to promote the development of eco-/cost-efficient Nordic wood-based pellet production by means of multidisciplinary research. Using Finnish conifer stem wood (bark-free Scotch pine sawdust and shavings) as a model raw material, the total functionality of a pilot-scale pellet facility combined with an extensive chemical toolbox was tested in this study to promote future development of eco- and cost-efficient wood-based pellet production in both quantitative and qualitative senses. Lignosulphonate, residual potato flour, and potato peel residue were used as adhesive binding agents. A pilot-scale pellet facility was equipped with a data logger for temperature and power measurements. The chemical toolbox included also novel specific staining and optical microscope methods and respirometric BOD Oxitop measurements. The results showed that adhesive binding agents increased the quality of pellets and changed inorganic characteristics, but did not have a significant effect on their calorimetric heat values. Lignosulphonate even increased the rate of production. Valuable information about both the pelletizing process and pellets is necessary in the future when developing good-quality pellets, a prime biofuel, from low-value and/or moist biomass that has undergone a cost-efficient drying process.