(Amyris uses its industrial synthetic biology platform to convert plant-sourced sugars into renewable hydrocarbons for fuel and chemical applications; Solazyme has developed a technology that harnesses the oil-producing ability of microalgae to develop renewable oil products.)

With more than 134,000 miles (215,652 km) 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. Results from the evaluation found that driving dynamics of the vehicles when powered by the renewable diesel were not negatively impacted while fuel economy was similar or improved.

(A 2013 evaluation by the California Air Resources Board (ARB) of renewable diesel in heavy-duty engines found that using 100% renewable diesel (R100) decreased emissions but also resulted in a slight (5%) increase in BSFC.)

In addition to comparable performance, both producers claim that greenhouse gas emissions (GHG) could be reduced by more than 50% on a well-to-wheel basis when using renewable fuels as compared to today’s commercially available crude-based fuels.

The successful completion of this collaboration with two leaders in renewable fuels and products highlights how far advanced fuel technology has come in recent years, proving that sustainable fuels are not only produced in more environmentally friendly ways, but can offer similar performance and lower emissions from a well-to-wheel perspective when compared with commercially available crude-based fuels. Evaluations like this are part of Volkswagen’s broader holistic environmental strategy which underscores the company’s commitment to the environment by deploying a comprehensive approach which addresses carbon reduction and sustainability at each part of the vehicle lifecycle.

—Ewald Goessmann, executive director, Volkswagen Group of America, Electronics Research Laboratory

These key indicators highlight the tremendous market potential that renewable fuel solutions offer, combining comparable performance and fuel economy, helping reduce emissions, while utilizing more sustainable methods to produce the products, Volkswagen said.

During the evaluation period, no engine errors were triggered as a result of the fuel and no extreme wear or failures were reported that would prevent any of the vehicles tested from being operated normally while powered with the respective renewable formulas. Additionally, engineers found that during the evaluation period there were no negative effects in the burning of the renewable fuels, while the production of soot was lower than when using conventional diesel.

As the evaluation comes to a close, the results and data collected make for a promising case for the use of renewable fuels in the years to come, Volkswagen suggested. The positive results highlight the possibility for new sustainable production pathways and open the door to more advanced innovation in the renewable fuel space. Volkswagen engineers will continue to analyze engine components and other data accumulated during the evaluation which could help in the enhancement of future vehicle components and refinement of renewable fuels.

The renewable diesel evaluation program is part of Volkswagen’s global strategy to become one of the world’s most environmentally friendly automakers by 2018. From a product perspective, the company seeks to reduce passenger fleet CO₂ with a goal of cutting emissions by 90% by 2050, improving fuel efficiency by 10-15% for every new model as compared to its predecessor, and by making other significant environmental improvements for each new model that’s introduced. In production, the brand is working to continue current efforts to help reduce GHG emissions at each production facility globally while increasing the use of renewable forms of energy at those facilities.

In the domain of biological pathways for renewable drop-in fuels, Audi (a Volkswagen Group company) is working with US-based Joule on the production and evaluation of engineered-cyanobacteria-derived renewable diesel and ethanol (earlier post). Audi is also working in the field of synthetic liquid fuels derived from renewable energy, CO₂ captured from air, and water. (Earlier post.)

Resources

• Georgios Karavalakis, Thomas D. Durbin, Robert L. Russell (2014) “Biodiesel and Renewable Diesel Characterization and Testing in Modern LD Diesel Passenger Cars and Trucks” CRC Project No. AVFL – 17b

• ARB Staff Report (2013) “Multimedia Evaluation of Renewable Diesel”