Quality properties of microwave-torrefied oat hull pellets were determined as a result of pelleting trials at different pellet die temperatures, sample particle sizes, and binder formulations. Microwave-torrefied ground biomass samples were compressed at two levels of pellet die temperatures (95°C and 145°C), two particle sizes (fine and coarse), and two levels of binders at different wt% (sodium lignosulfonate and sawdust). Quality of pellets was examined based on relaxed pellet density, pellet tensile strength, moisture absorption, moisture content, ash content, and higher heating value. Results showed that pellets made from fine particle size at high die temperature (145°C) have improved density and tensile strength. The best binder for density and tensile strength improvement was 10 wt% sodium lignosulfonate. However, since raw sawdust is abundantly available and cheaper than lignosulfonate, it is best recommended as a low-cost effective binder for densifying torrefied oat hull into pellets. Overall, all the densified pellets had a moisture content of 4–5% wet basis. Moisture absorption decreased when increasing torrefaction temperature, and pellets formulated with lignosulfonate presented higher moisture absorption and lower calorific value. Moreover, the addition of lignosulfonate significantly increased the pellet ash content, while sawdust significantly decreased the ash content of microwave torrefaction oat hull pellets.
