Drying of Prickly Pear (Opuntia ficus-indica (L.) Miller) and Its Potential as a Solid Biofuel

Abstract

Prickly pear is a species that shows great capability to grow in harsh environments with potential for being used as an energy resource. The aim of this paper was to characterize prickly-pear mature cladodes in terms of chemical, proximal, and fuel properties, as well as to study the drying kinetics of this biomass after pretreatments destined to expose the internal tissues of mature cladodes to different temperatures. The results show that prickly-pear biomass was a poor-quality solid biofuel due to a low calorific value (12.9 MJ/kg d.m.b.) and a high ash content (25.8 wt.%). When drying prickly-pear biomass, cutting the cladodes to expose the internal tissues significantly increased the drying rate, especially when temperatures of 60 °C and above were employed. Double exponential (three parameters) and Midilli were the models that best fitted the experimental curves of prickly-pear cladodes cut into straps and cubes when dried at 50–70 °C. Finally, the bulk density of the prickly-pear biomass was similar to the one obtained for herbaceous biomasses, thus suggesting that further densification will enhance the usability of this feedstock.