Audi remains convinced of the potential of the fuels e-gas, “e-benzin” (e-gasoline) and e-diesel and is continuing to pursue its e-fuels strategy. (Earlier post.) Audi and its development partners Global Bioenergies S.A. (earlier post) and the Fraunhofer Center for Chemical Biotechnological Processes (CBP) now report that they have for the first time produced a sufficient quantity—60 liters (15.9 gallons US), the largest batch yet produced—of synthetic Audi e-gasoline for initial engine tests.
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.—Reiner Mangold, Head of Sustainable Product Development at Audi AG
Audi “e-benzin” (e-gasoline) 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) uses additional hydrogen to transform it into isooctane (C8H18), ETBE and isododecane (C12H26). The fuel is free of sulfur and benzene and is therefore especially low in pollutants when it burns.
Currently, only a small part of Global Bioenergies’ ton scale isobutene production is directed toward e-fuels, using Fraunhofer’s lab scale conversion unit. The e-fuel production capacity will be significantly increased in 2019 with the addition to the Leuna Demo plant of a dedicated fuel production unit, which will allow the production of renewable gasoline batches.
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. (Earlier post.)
Audi’s alternative fuels already offer great potential for sustainable mobility and are helping reduce CO2 emissions from combustion engines by up to 80% in g-tron models, for example.
For Audi, e-fuels are more than just a subject of research in laboratories. Since 2013, the brand with the four rings 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). (Earlier post.)
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. (Earlier post.)
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. (Earlier post.) For the first time, hydroelectric power is the sole energy supply required for this.