Comparison of Bio-Oil and Waste Cooking Oil as Binders during the Codensification of Biomass: Analysis of the Pellet Quality

Codensification is a promising technique to convert biomass into high-quality energy pellets. In this research, the effect of apple tree bio-oil and waste cooking oil as binders on logistical, storage and combustion characteristics of composite pellets with corn straw and corresponding biochar was comparatively studied. The results showed that apple tree pyrolysis bio-oil performed better than the waste cooking oil in improving the physical stability, energy density and moisture resistance of the pellets. For bio-oil as a binder, the optimum ratio of binder, water, corn straw and biochar is 6:10:40:40, and the ratio of that is 10:10:50:30 for waste cooking oil. 41.67 wt% biochar could be added in pellet B6-40-40 which has the highest energy density up to 20.50 GJ/m(3). In addition, the apple tree pyrolysis bio-oil can more effectively promote the moisture resistance of pellets than waste cooking oil. Above all, the composite pellets with the bio-oil binder exhibited superior qualities, indicating the produced bio-oil could be used as a promising binder for the production of sustainable fuel pellets.