The development of Audi e-fuels has taken another step forward.

Audi announced its synthetic fuels have now completed a test cycle in Ingolstadt in the pressure chamber and the glass engine – with clear results: Audi e-fuels often even perform better than their conventional counterparts.

“Our test shows that as well as electric driving on renewable electricity, there are other concepts that permit long-distance, low-emission driving,” commented Reiner Mangold, head of Sustainable Product Development at Audi.

Audi explained the engineers were first and foremost interested in mixture preparation and the synthetic fuels’ combustion characteristics. To investigate these, they simulated the conditions inside an engine in a pressure chamber at up to 218 psi (15 bar) and temperatures of 660 degrees F (350 degrees C). A special camera recorded how the fuel behaves during the injection process to monitor optimal combustion.

The glass engine was another test station. This test setup reveals what happens inside the cylinders. A small window made of quartz glass allows for the observation of the fuel’s behavior in the cylinder and how it interacts with the airflow in the combustion chamber.

During each of up to 3,000 revolutions per minute in the research engine, a tiny amount of fuel shoots into the glass cylinder, is compressed and ignited, and the exhaust gas is then expelled.

Audi engineer’s conclusion: unlike fossil fuels, the composition of which varies depending on their place of origin, synthetic Audi e-fuels are absolutely pure fuels. Thanks to their chemical properties, fewer emissions are generated when they are burned.

Audi added these e-fuels do not contain any olefines or aromatic hydrocarbons; as a result, the synthetic fuels assure a more effective mixture preparation process, cleaner combustion and lower emissions.

The next task for Audi’s engineers is to optimize the production process for e-ethanol and e-diesel. This will allow these new fuels to be ready for the market.

Audi operates a research facility in Hobbs (New Mexico, United States) for the production of e-ethanol and e-diesel in partnership with Joule. Audi said at this facility, microorganisms use water (brackish, salt or wastewater), sunlight and carbon dioxide to produce high-purity fuels.

The e-gas project in Werlte, Germany, is another component of Audi’s extensive e-fuels strategy. Audi said it demonstrates how large amounts of green power can be stored efficiently and independently of location by transforming it into methane gas and storing it in the natural gas network.