Application of fast pyrolysis bio-oil in a genset engine for combined heat and power generation

Fast pyrolysis bio-oil made from biomass residues has promising potential in combined heat and power generation applications. However, the special physicochemical properties of FPBO make its application in engines challenging, and the long-term engine operation on FPBO has not been achieved in previous studies. In the EU funded SmartCHP project, a single-cylinder diesel engine test rig has been established with major modifications to investigate an engines performance running on fast pyrolysis bio-oil. A 500 h engine durability test using FPBO blended with 10% ethanol and a 72 h durability test using neat FPBO have been successfully achieved on the modified engine for the first time. Considering that a small amount of ethanol addition to FPBO can significantly improve its stability during long-term storage and mitigate engine wear, FPBO blended with 10% ethanol is subsequently used to investigate engine injection, combustion, and emission characteristics. The increased intake temperature slightly reduces the ignition delay of FPBO but has negligible influence on diesel combustion. FPBO reduces the amount of NO_x by nearly a factor two when compared to diesel, but increases CO emissions at the same operation conditions with a factor two as well. FPBO shows a higher CO emissions and a lower NO_x emissions compared to other renewable fuels such as ethanol, butanol, and hydrotreated vegetable oil. The optimized net indicated efficiency for the engine running on FPBO is 53.6%, higher than that of diesel (49.1%) since FPBO has a faster burning rate.