Pelletization of eucalyptus wood and coffee growing wastes: Strategies for biomass valorization and sustainable bioenergy production

Abstract

The global energy matrix is based on the use of fossil fuels, which are the main contributors of the greenhouse effect. There are several different alternatives to minimize this problem, such as the pelletization of agroforestry wastes for bioenergy purposes. The aim of this research was to evaluate the potential of forest biomass (eucalyptus wood [E]) and agricultural residues of coffee processing (parchment [P], silver skin [S] and coffee husk [CH]) for pellets production focusing on the generation of energy and to classify them according to commercialization standards. Different proportions of forest biomass mixed with coffee residues were evaluated and used for the production of the pellets with six compositions (EPCH and EPS). Additionally, three coffee processing residues were individually pelleted (100% pure). The pellets with the composition eucalyptus-parchment-coffee husk (ECPCH) had greater durability (98.17%), hardness (37.12 kg) and net energy density (11.60 GJ m−3), and are eligible for commercialization and export according to European standards (type B). The pellets produced with biomass blends provide better energy results (16.51–17.08 MJ kg−1), compared to pellets produced only with CH (15.76 MJ kg−1) and S (16.26 MJ kg−1). The biomass blends positively influenced the bulk density, mechanical durability, and combustibility of pellets.