Audi Advances its E-Fuels Technology & Begins Synthetic Fuel Testing

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【Summary】German automaker Audi is researching how synthetic technology can be used to improve gasoline, making it burn cleaner and therefore become more environmentally friendly.

Eric Walz    Mar 16, 2018 4:49 PM PT
Audi Advances its E-Fuels Technology & Begins Synthetic Fuel Testing

Synthetic motor oil has been around since the 1960's. Mobil first developed a synthetic grease to prevent military aircraft wheel bearings from failing when landing in extreme cold temperatures. Now, German automaker Audi is researching how synthetic technology can be used to improve gasoline, making it burn cleaner and therefore become more environmentally friendly.

For the past several years, Audi has been developing "e-benzin", a new type of synthetic fuel for internal combustion engines. Audi successfully produced the first batch of the new synthetic fuel in 2015. Audi engineers are now examining the combustion and emission behavior of the renewable fuel in a test engine.

Together with Global Bioenergies S.A. in Leuna, Germany the largest batch of e-gasoline ever produced – 60 liters (15.9 US gal) – has been achieved.

Produced Without Petroleum

Audi's "e-benzin" is synthetically produced without the use of petroleum. The fuel is 100-percent iso-octane and therefore has an outstanding octane rating of RON 100. The octane rating of fuel designates the fuel's ability to resist detonation. In today's modern high-compression automobile engines, heat and compression can cause fuel to ignite prematurely, causing loss of power, efficiency and possibly lead to engine damage. Fuels with higher octane ratings lessen the chance of this occuring.

In addition, Audi "e-benzin" contains no sulfur or benzene, the fuel burns very cleanly. E-benzin is a high-grade fuel that enables engines to utilize high compression ratios for enhanced efficiency and more power output.

Audi is 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.

In the case of synthetic Audi "e-benzin" (e-gasoline), the Ingolstadt company has now achieved an important intermediate goal. Together with their development partners, they have for the first time produced a sufficient quantity of the new fuel 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," said Reiner Mangold, Head of Sustainable Product Development at AUDI AG. Audi "e-benzin" (e-gasoline) is essentially a liquid isooctane (octane).

Octane an important component of gasoline, frequently used in relatively large proportions to increase the knock resistance of the fuel. Octane is currently produced from biomass in a two-step process.


How E-Benzin is Made

In the first step, Global Bioenergies produces gaseous isobutylene (C4H8) in a demonstration plant. In the second step, the Fraunhofer Center for Chemical Biotechnological Processes (CBP) uses additional hydrogen to chemically transform the C4H8 into isooctane (C8H18). The end result is a fuel that is free of sulfur and benzene and is therefore especially low in pollutants when it burns.

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 organic 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. Audi's g-tron models run primarily on compressed natural gas (CNG).

For Audi, e-fuels are more than just a subject of research in the lab. Since 2013, the automaker 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, Germany.

Drivers can fill up their Audi g-tron models 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 measuring the reduction of CO2 emissions.

Diesel Applications

E-fuels technology can also be used in diesel fuel. Audi's 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 then 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, the 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 source of energy required for production.

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