BIOMASS AND ENERGY CHARACTERISTICS OF MARALFALFA GRASS (Cenchrus purpureus Schumach.) Morrone CULTIVATED IN WARM SUBHUMID CLIMATE TO PRODUCE BIOETHANOL

Abstract

Biofuels are a sustainable energy option that can contribute to solve some current environmental problems. For example, it seems imperative to find alternative energy sources; and among them adequate and sustainable raw materials to produce biofuels, such as bioethanol. This study, under the assumption that Maralfalfa grass would be a suitable substrate to produce biofuel, aimed at evaluating the biomass yield, chemical composition, and theoretical bioethanol production of Maralfalfa grass (C. purpureus Schumach.) Morrone harvested at three cutting frequencies (CF). Treatments were distributed in a randomized complete blocks design with split-plots arrangement and three replicates. Analysis of variance was done with GLM procedure and means were compared with Tukey test (p≤0.05). At 120 d, the lignocellulosic material content was the highest (p≤0.05) with 66% of holocellulose, 30% hemicellulose, 22% lignin, 1.8% acid soluble lignin, 20% acid insoluble lignin, 26% acid insoluble residue, and 6.2% ashes. The highest concentration of extractives compounds was found at 150 d harvest frequency (15.5%; p≤0.05), while the highest biomass production (32.6 Mg ha-1 y-1), calorific value (21.0 MJ kg-1), and bioethanol production (239.9 L Mg-1 MS-1) was obtained at the 180 d (p≤0.05). No significant changes were found for crude protein (p>0.05). Results showed that Maralfalfa grass (C. purpureus Schumach.) Morrone is an attractive alternative for bioethanol production due to high biomass yield and chemical composition at short harvesting times.