Comparative energy properties of torrefied pellets in relation to pine and elephant grass pellets

Abstract

Torrefaction is a thermal process that improves the energy properties of plant biomass pellets, providing greater biofuel efficiency for gasification technologies, as well as replacing coal in thermoelectric plants. In Brazil, many agroforestry residues can be improved in value through this technological process, transforming them into modern solid biofuels. There are few studies comparing torrefied wood and elephant grass pellets, especially in relation to their energetic characteristics. This study analyzed the high heat value, energy density, ash content, fixed carbon, volatile materials, lignin, holocellulose, extractives, bulk density, and mechanical durability of these pellets. Due to the absence of Brazilian normative standards for these pellets, the international standard ISO 17225 (2014) was used for comparisons. The results revealed substantial differences among the samples, mainly regarding their moisture content, higher heating value, and energy density in torrefied pellets. It was concluded that these torrefied pellets are biofuels having lower water adsorption, higher heating value, and higher energy density than the pine and elephant grass pellets.