Evaluation of sustainable manufacturing of pellets combining wastes from olive oil and forestry industries

Use of agroindustrial wastes helps productive processes to have a more sustainable development. In this work, the physical-chemical characteristics of alperujo and orujo residues were studied, demonstrating that both can be combined for pellet production. For this purpose, 12 types of pellets based on different combinations of alperujo, orujo, Pinus radiata and Populus spp. materials were manufactured in the laboratory. Their energetic and physical properties were analyzed using different ISO standards, resulting in eight suitable samples that complied with regulations. A comparative cost analysis was also carried out to evaluate the profitability of the pellets produced compared to the traditional pellets from Pinus radiata. It was concluded that profitability increased by 11.0% when producing pellets with a Pinus radiata mixture, mainly due to the decrease in acquisition, sawing and transportation costs. In addition, sustainable pellets production decreased emissions by 5.0% (78,780 tonnes CO2 year(-1)). The most profitable mixture was that of alperujo/Pinus radiata 90/10 w/w, due to both reduced costs and a reduction in CO2 emissions. Sustainable pellets showed as perfectly suitable to be used as a solid biofuel.