Volkswagen of America’s renewable diesel evaluation program, in collaboration with renewable fuel and product companies Solazyme and Amyris, has shown greenhouse gas emissions could be reduced by more than 50 percent on a well-to-wheel basis when using renewable fuels as compared to today’s commercially available crude-based fuels.
Beginning in 2012, Volkswagen measured the environmental impacts from the use of pre-commercial renewable diesel formulas with TDI Clean Diesel technology found in the 2012 Passat TDI (which uses a NOx storage system) and 2012 Jetta TDI (SCR system). Initial analysis found that advanced renewable fuels in the test offered comparable performance to standard crude-based diesel fuel blends while producing less CO2 emissions on average.
During the two-year evaluation, Solazyme’s now commercial, Soladiesel RD (100-percent algae-derived renewable diesel fuel) and the Amyris plant-sugar derived renewable diesel formula was used for the program with each company testing a 2012 Passat TDI and Jetta TDI models. Both fuel producers added additives, which are commonly used today, to meet ASTM D 975 specifications.
With more than 134,000 miles logged collectively in real-world, on-road and on-highway conditions, Volkswagen engineers found that every vehicle in the evaluation offered similar performance to existing TDI powertrains operating on today’s crude-based clean diesel fuels. While powered by the two fuel formulas, results from the evaluation found that driving dynamics were not negatively impacted while fuel economy was similar or improved.
In the automaker’s other efforts to reduce its carbon footprint, Volkswagen has ordered air conditioning systems that use CO2 as a coolant for its VW Phaeton and the Audi A8.