Casca de pequi (Caryocar brasiliense Camb.) como matéria-prima para biocombustíveis sólidos: avaliação energética e produção de briquetes

Abstract

The search for renewable energy sources has stimulated the use of organic waste as raw material for bioenergy production. The pequi (Caryocar brasiliense Camb.) production chain plays an important economic and social role, especially in the state of Minas Gerais. However, the commercialization of the fruit generates a significant amount of peel that, if disposed of improperly, can contribute to the overload of waste management systems and environmental degradation. In order to add value to this by-product, this study evaluated the energy potential of pequi peel biomass for the production of briquettes at different moisture contents (5%, 7.5%, and 10%). The physical, mechanical, and thermal properties of the raw biomass under study were evaluated, as well as how production moisture and carbonization temperature influence the energy properties of these briquettes. Carbonization was performed at two final temperatures (360°C and 480°C) at a rate of 1.5°C min-1. To verify this influence, the gravimetric yield based on dry mass, immediate analysis, gross calorific value (GCV), bulk density, energy density, and breakage index were determined. The experiment followed a completely randomized design in a factorial arrangement, considering the production moisture of the briquettes and the final carbonization temperature. The raw biomass had a high content of volatile material (74.41%), fixed carbon (22.69%), and a calorific value of 14.23 MJ kg-1, showing the effectiveness of the material for energy production. Chemical analysis showed 69.38% extractives, 10.27% lignin, and 20.35% holocellulose. Thermogravimetric analysis of the bark revealed behavior compatible with that of lignocellulosic biomasses. Briquettes produced with lower moisture content showed greater mechanical resistance. Carbonization at 480 °C resulted in an increase in the fixed carbon content and PCS of the briquettes, although with lower gravimetric yield. The effects of moisture were more evident in carbonization at 360 °C, indicating a temperature-dependent interaction. The results of this study demonstrate the potential of pequi peel as a raw material for the production of solid biofuels, promoting the use of agro-industrial waste and supporting initiatives aimed at the circular economy and aligned with the low-carbon energy transition.