Avocado Tree Pruning Pellets (Persea americana Mill.) for Energy Purposes: Characterization and Quality Evaluation

The energy use of fruit tree pruning represents a current alternative to achieving an energy transition toward clean biomass resources, which can substitute for fossil fuels and mitigate polluting emissions. In Mexico, avocado is one of the most important fruit crops, with approximately 260,000 ha planted. The pruning of avocado trees generates large amounts of biomass that are not fully exploited, lacking studies that analyze in depth the energy potential of pruning. This study aims to determine the potential energy use of avocado pruning as densified solid biofuels. The physical, chemical and energetic properties of two pruning fractions defined as class B (branches) and class BAL (branches and leaves) were determined. From class B, pellets were made, and their physical and mechanical properties were determined. Subsequently, the evaluated parameters of the pellets obtained were compared to European quality regulations to determine their quality and identify their potential uses. The characterization of avocado pruning indicates that class B generally has better physicochemical characteristics than class BAL to be used as solid biofuel. It was found that class B has a high calorific value (19.61 MJ/kg) and low ash content (1.2%), while class BAL contains a high amount of ash (7.2%) and high levels of N (1.98%) and S (1.88%). The manufactured pellets met most of the quality requirements for immediate use in the residential, commercial and industrial sectors at the regional level.