Biodiesel is a renewable fuel product made from triglycerides with properties similar to petroleum-based fuel. It is blended with various petroleum fractions to produce automotive and transportation fuels and is not typically utilized as a standalone fuel. Biodiesel can be manufactured from various feedstock including straight vegetable oils (SVO), waste vegetable oils (WVO), and animal fats. Although most U.S. biodiesel is made from SVO, using WVO feedstock is a much cheaper option. As biodiesel fuel offers certain advantages over petroleum based fuels, the aviation industry has gradually advanced the use of the fuel in gas turbine engines. However, increased viscosity and higher cloud point can create performance issues in an aviation gas turbine engine. Testing the performance of biodiesel fuels in aviation gas turbine engines is important to further the expanded use of these fuels in the industry.

Three fuels were tested as part of the study: B100 biodiesel, B11 biodiesel, and Jet-A. The B100 was manufactured as part of this study using soybean based WVO feedstock. The manufacture of this fuel is included in the methods of the paper. A Rolls Royce Allison 250-C20 turboshaft engine was operated on each of the three fuels to measure starting capability, fuel pressure, turbine rpm (%N1 & %N2), exhaust temperature, and time from initial start to max %N1. Each run was performed with an identical process and recorded to capture the data points. The fuel system was purged between fuel changes to eliminate cross-contamination. Jet-A fuel enabled the engine to start properly and remain operational until shut down, but neither B11 nor B100 maintained rpm with the starter disengaged. B11 fuel did start and operate the engine; however, B100 failed to start the engine when hot. Our conclusions are to recommend further testing with lower viscosity fuel before recommending WVO based biodiesel fuel in aviation gas turbine engines.