By Audi Media
In collaboration with the U.S. firm Joule, Audi is taking a fundamentally new approach to the diesel fuel of the future. The biotech company, founded in 2007 and based in Bedford, Massachusetts, is working on producing synthetic fuels – Audi e-diesel and Audi e-ethanol – with the help of special microorganisms. They are virtually climate-neutral, as they only release as much CO2 during combustion as was bound during production. According to current projections, a car operated on Audi e-diesel will achieve a good carbon footprint similar to that of a battery-electric car using electricity produced from renewable sources.
Audi e-diesel and Audi e-ethanol require water, CO2, solar energy and special microorganisms – single-cell organisms measuring roughly three-thousandths of a millimeter. Just as plants do, these organisms operate with what is known as oxygenic photosynthesis – they utilize sunlight and CO2, e.g. from waste gases, to form carbohydrates and grow. They do not need an environment of clean drinking water; saltwater or wastewater is sufficient. One of the byproducts of oxygenic photosynthesis is oxygen.
The experts at Joule have modified this photosynthesis process such that these microorganisms produce alkanes – important components of diesel fuel – and ethanol directly from the carbon dioxide. The fuels are separated from the water and cleaned.
Audi e-diesel offers the advantage of high purity – it is free of sulfur and aromatics. This is in stark contrast to petroleum-derived diesel, which is a mixture of a wide variety of hydrocarbon compounds. The new fuel will also offer excellent ignition performance thanks to its high cetane number. And its chemical composition will permit unlimited blending with fossil fuel diesel. No major modifications are required in order to operate Audi’s clean diesel engines on Audi e-diesel.
In 2012, Audi and Joule jointly built a demonstration facility in Hobbs, New Mexico (USA) – a barren, non-arable region with lots of sunshine. The two companies have been partnering since 2011. The American company has patented its technology; Audi is Joule’s exclusive automotive partner. Audi engineers are contributing their expertise in the area of fuel and engine testing and the preparation of LCAs (life cycle assessments) to the development of marketable fuels, the production of which could begin within the next few years.
Audi’s activities in the development of CO2-neutral fuels extend beyond the partnership with Joule, however. The Audi e-gas plant in Werlte, Lower Saxony, is the world’s first industrial power-to-gas plant. It produces synthetic methane, thus making it possible to store large amounts of wind and solar energy. Besides the green electricity, the process requires nothing other than water and CO2. Audi is also conducting joint research into the synthesis of Audi e-gasoline with Global Bioenergies of France.