Bio-oil from Pine Residues-Yields, Quality and Potential Applications A case study on the valorization of Zimbabwe's Timber Residues

Pyrolysis has received attention as a potentially low cost thermochemical method that can efficiently utilize lignocellulosic residues. The bioenergy derived can bring many socio-economic benefits, especially to remote areas in developing nations like Zimbabwe. This study explores the potential valorization of pine residues to bioenergy from sawmills located in such remote areas through pyrolysis. Characterization of these residues indicated that they could be a good feedstock for pyrolytic conversion due to the relatively high volatile matter (79.16^%), low ash content (0.83^%) and high gross calorific value (17.6 MJ/kg). This study focuses on the actual pyrolysis and characterization of the product bio-oil, comparing its properties to conventional fuels. The primary goal is to use the bio-oil in stationary engine applications for power generation in such remote areas, in a country with a 40% electricity access and only 19% of rural areas electrified. The optimum pyrolysis temperature was found at 500°C, while the optimum primary condenser temperature with the best quality oil, was at 110°C. At the condenser temperature of 125°C the bio-oil appeared to have decomposed to a lower viscosity substance, while at 140°C most of the substance volatized. The best quality oil had the highest calorific value (15.780MJ/kg), confirming its quality status. The viscosity of this oil was found to be 10,151mPa.s. Gas chromatography was also carried out on the oil samples and the compounds with the highest mass presence were catalogued. It is concluded that the bio-oil could be used in moderate-slow engines with moderate upgrading, while it needs to be diluted with a solvent then blended with a diesel for use in fast diesel engines. It is also important to establish the particulate composition and flash point of the bio-oil, though these tests were not carried out in this study.