Audi begins testing new ‘e-benzin’ fuel

German luxury carmaker Audi has begun carrying out tests of ‘e-benzin’ (e-gasoline) as it continues to pursue its e-fuels strategy. Together with its development partners, it has for the first time produced a sufficient quantity of regeneratively produced fuel for initial engine tests.

Together with Global Bioenergies in Leuna (Saxony-Anhalt), the largest batch of e-gasoline ever produced – 60 litres – has been achieved. “Like all Audi e-fuels, the new fuel has many advantages. It isn't dependent on crude oil, it is compatible with the existing infrastructure and it offers the prospect of a closed carbon cycle,” said Reiner Mangold, Head of Sustainable Product Development at Audi AG.

Audi e-benzin is essentially a liquid isooctane. It is currently produced from biomass in a two-step process. In the first step, Global Bioenergies produces gaseous isobutene (C₄H₈) in a demonstration plant. In the second step, the Fraunhofer Center for Chemical Biotechnological Processes (CBP) in Leuna uses additional hydrogen to transform it into isooctane (C₈H₁₈). The fuel is free of sulfur and benzene and is therefore especially low in pollutants when it burns.

Audi engineers are now examining the combustion and emission behavior of the renewable fuel in a test engine. As a high-purity synthetic fuel with very good anti-knock properties, Audi e-benzin (e-gasoline) offers the possibility to further increase engine compression and thus boost efficiency. Over the medium term, the project partners aim to modify the production process so that it will not require biomass – in this case, CO₂ and hydrogen produced from renewable sources should be sufficient source materials.

Audi’s alternative fuels already offer great potential for sustainable mobility and are helping reduce CO₂ emissions from combustion engines – by up to 80 percent in g-tron models, for example.

For Audi, e-fuels are more than just a subject of research in laboratories. Since 2013, the carmaker has been offering renewable Audi e-gas on the market. It originates in part from the company’s own power-to-gas plant in Werlte (Emsland). Customers fill up their Audi g-tron model at any CNG filling station and pay the regular price for it. By feeding the computed volume of Audi e-gas into the natural gas grid, Audi ensures the green benefits of the program, including the corresponding reduction in CO₂ emissions.

Audi e-diesel is also part of the Audi e-fuels portfolio. In Dresden, Audi’s cooperation partner Sunfire operated a pilot plant for this purpose from late 2014 to October 2016. As in Werlte, green electricity supplied the energy, and water and CO₂ were also used as raw materials. The end product was called Blue Crude, which was refined into Audi e‑diesel. Audi is currently planning production capacity in Laufenburg in the Swiss canton of Aargau. Together with partners Ineratec GmbH and Energiedienst Holding AG, a new pilot plant will produce around 400,000 liters of Audi e-diesel per year. For the first time ever, hydroelectric power is the sole energy supply required for this.