Title: Effect of Torrefaction on Chemo-Physical Characteristics of Densified Corn Stover for Bioenergy Applications
Authors: Olosunde A. A. Prof. Ibrahim J. S. Kuhe, A.
Volume: 10
Issue: 5
Pages: 60-69
Publication Date: 2026/05/28
Abstract:
The escalating demand for renewable energy has spotlighted lignocellulosic biomass, particularly abundant agricultural residues like corn stover, as a viable alternative to fossil fuels. However, raw corn stover suffers from low energy density, high moisture susceptibility, poor handling properties, and inefficient combustion, limiting its direct use in bioenergy systems. This study investigates the integrated effects of torrefaction and densification on the chemo-physical properties of milled corn stover (MCS) sourced from Nigeria, aiming to upgrade it into a high-quality solid biofuel. Corn stover was torrefied in a fixed-bed reactor under nitrogen atmosphere at temperatures of 200-300 °C for 60 min residence time, followed by pelletization. Comprehensive characterization included ultimate analysis (C, H, O, N, S), molecular composition (hemicellulose, cellulose, lignin), proximate analysis (moisture, volatiles, fixed carbon, ash), and energy assessment (higher and lower heating values). Results showed progressive carbon enrichment (45.92% to 54.14%), reductions in oxygen (46.13% to 42.32%) and hydrogen (6.18% to 5.04%), and lowered O/C and H/C ratios, indicating coal-like characteristics. Hemicellulose degraded markedly (31.00% to 7.30%), volatiles decreased (76.5% to 40.1%), fixed carbon increased (17.7% to 36.9%), and higher heating value rose from 16.28 MJ/kg to 18.67 MJ/kg. Densification of torrefied material produced uniform pellets with enhanced calorific values (up to 19.03 MJ/kg), low moisture (down to 1.42%), and improved physical stability. These upgrades enhance hydrophobicity, storage durability, grindability, and combustion efficiency, making torrefied-densified corn stover suitable for co-firing, gasification, or standalone bioenergy applications. The process valorizes underutilized residues, mitigates open burning pollution, and supports sustainable energy in agricultural regions like Nigeria. Optimal torrefaction at 260-300 °C maximizes benefits, with future work recommended on scale-up, emissions, and techno-economic viability.