Date of Graduation


Document Type


Degree Type



Davis College of Agriculture, Natural Resources and Design


Wood Science and Technology

Committee Chair

David DeVallance

Committee Co-Chair

Gloria Oporto

Committee Member

Jingxin Wang


Biomass properties have a potential to be improved by torrefaction, a thermal pretreatment process that removes hemicellulose. The intent in using torrefaction for biomass is to increase the carbon content and calorific value, as well as reduce the hydrophilic nature of woody-biomass. To facilitate the handling and use of torrefied biomass, densification (e.g. pelletizing) is used to compact it into standard uniform shape pellets with high density and mechanical strength. In this thesis, torrefaction as pretreatment, as well as moisture content and particle size of raw biomass materials before pelletizing were studied as parameters that may affect the biomass pellet quality including: compaction behavior, gross heating value, hardness, and moisture resistance. Woody biomass red oak (Quercus rubra), and two species of grass-type biomass switchgrass (Panicum virgatum), and miscanthus (Miscanthus giganteus) were used in the experiment. Results of this research indicated that torrefied biomass required 50% ~ 200% more pelletization energy than non-torrefied biomass. Additionally, in general, the hardness of torrefied biomass pellets was lower than non-torrefied pellets. However, it was found that the moisture resistance of the torrefied biomass pellets was higher than the non-torrefied pellets. The moisture content and particle size also showed some relatively small effects on the biomass pellet properties, but their influence varied from species to species, and even between pretreatments within one species. Therefore, based on the results of this research, the better moisture content and particle size for pellet production was specific to each type of pretreatment and species.