Audi advances regenerative e-fuels technology

Together with Global Bioenergies S.A. in Leuna (Saxony-Anhalt), Audi has achieved the largest batch of e-gasoline ever produced (60 litres).

Reiner Mangold, head of Sustainable Product Development at AUDI, said: “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.”

Audi “e-benzin” (e-gasoline) is essentially a liquid isooctane, and it is currently produced from biomass in a two-step process.

Audi reported, that in the first step, Global Bioenergies produces gaseous isobutene (C4H8) in a demonstration plant. Then, the Fraunhofer Centre for Chemical Biotechnological Processes (CBP) in Leuna uses additional hydrogen to transform it into isooctane (C8H18).

The German carmaker reported, that the fuel is free of sulphur and benzene and is therefore especially low in pollutants when it burns.

Audi engineers are now examining the combustion and emission behaviour 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.

Contribution to sustainable mobility

Audi’s alternative fuels already offer great potential for sustainable mobility and are helping reduce CO2 emissions from combustion engines by up to 80%.

For Audi, e-fuels are more than just a subject of research in laboratories. Since 2013, the car maker 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), and 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.

Green electricity and E-diesel

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.