Cellulosic Ethanol Fuel Quality Evaluation and its Effects on PFI Intake Valve Deposits and GDI Fuel Injector Plugging Performance

The U.S. Renewable Fuel Standard 2 (RFS2) mandates the use of advanced renewable fuels such as cellulosic ethanol to be blended into gasoline in the near future. As such, determining the impact of these new fuel blends on vehicle performance is important. Therefore, General Motors conducted engine dynamometer evaluations on the impact of cellulosic ethanol blends on port fuel injected (PFI) intake valve deposits and gasoline direct injected (GDI) fuel injector plugging. Chemical analysis of the test fuels was also conducted and presented to support the interpretation of the engine results. The chemical analyses included an evaluation of the specified fuel parameters listed in ASTM International's D4806 denatured fuel ethanol specification as well as GC/MS hydrocarbon speciations to help identify any trace level contaminant species from the new ethanol production processes.

While the cellulosic ethanol engine test results varied nominally depending on the type of feedstock used, the average cellulosic ethanol results were determined to be equivalent to corn-based ethanol samples tested.