Evaluation of key fuel properties of three generation biodiesel fuels: an experimental investigation of feedstock type

Transportation sector is one of the most important causes of environmental problems such as global warming and acid rain. To reduce transportation's negative impacts on the environment, it should be made carbon neutral. Although electrification has been very popular in recent years, internal combustion engines will continue to dominate transportation for a long time. Biodiesel can be produced from varios feedstocks and is classified into three generation according to its feedstock origin. However, the fuel properties of biodiesel fuels of different generations vary significantly depending on feedstock. Biodiesel fuels' physico-chemical fuel properties greatly influence the engine characteristics and exhaust emissions. In this experimental study, 13 different biodiesel fuels' (including three generations) some key fuel properties such as kinematic viscosity, density, flash point, cold filter plugging point and cetane index were determined and compared with each other. The highest and the lowest kinematic viscosities were measured for Waste Cooking Oil Biodiesel and Soybean Oil Biodiesel, respectively. Among the biodiesel fuels, only Waste Cooking Oil Biodiesel and Waste Chicken Fat Biodiesel could not meet the viscosity specification in EN 14214. The density values of test fuels were very similar (between 875.83 kg.m-3 and 891.46 kg.m-3) and all were within the required specification range. The lowest flash point (142 °C) was measured for Algae Oil Biodiesel. It was considerably lower than other fuels. The highest flash point (184 °C) belonged to Hazelnut Oil Biodiesel. Waste Fleshing Oil Biodiesel and Waste Cooking Oil Biodiesel had the highest (58.80) and lowest (50.54) cetane values, respectively. However, all biodiesels met the minimum cetane value given in European biodiesel standard. The most significant differences (ranged from -10 °C and 10 °C) between the fuel properties of biodiesels of different origins were observed in CFPP. The viscosity and poor cold flow properties of waste feedstock-based biodiesels may cause critical problems in diesel engines. Nevertheless, they can be blended with other biodiesels or petro-diesel in certain amounts. Among the biodiesel fuels of different origins tested in this study, algae oil biodiesel has the best physico-chemical fuel properties and technical potential.