Audi develops a diesel that doesn’t need old dinosaurs to work.
For years, a fundamental argument against the use of cars has been the consumption of fossil fuels. Many methods have been used to try and ease the strain on the world’s natural resources, from alternative fuels to increased combustion engine efficiency.
But now Audi reckons it’s come up with a new solution – a carbon-neutral synthetic diesel made from water and carbon dioxide. It’s just produced the first batch of what it calls Audi e-diesel at a research facility in Dresden, Germany, and to demonstrate its suitability for general use, the first five litres have powered the Audi A8 of a German government minister.
Audi has been working since 2012 with an energy technology company in Dresden called sunfire to develop the new fuel. You’ll have to forgive us for being slightly sketchy on the exact science – it wasn’t our strongpoint at school – but the production works on the power-to-liquid principle, and the only raw materials used are water and carbon dioxide. The CO2 is supplied by a biogas facility and captured from the ambient air by a technology called direct air capturing.
The water is heated to form steam, and then broken down into hydrogen and oxygen by high-temperature electrolysis. The hydrogen reacts with CO2 in synthesis reactors under high pressure and high temperature, and the result is a liquid known as ‘blue crude’ – a product not dissimilar to fossil crude oil. This can be refined to yield the end product – e-diesel. The synthetic fuel has a high cetane number that makes it easily ignitable, and lab tests at Audi have shown it can be used for mixing with regular diesel, or potentially for using as a fuel in its own right.
Audi’s head of sustainable product development, Reiner Mangold, reckons the new fuel, and others like it, will be very important in the future as a technology that complements, rather than replaces, electric vehicles.
“In developing Audi e-diesel we are promoting another fuel based on CO2 that will allow long‑distance mobility with virtually no impact on the climate,” he said.
This isn’t the first eco-fuel that Audi has developed. It’s worked with sunfire since 2009 and has already developed a synthetic methane called e-gas, which can be used in certain models of the Audi A3 Sportback in Germany. In addition, the firm is working with a French company to develop e-gasoline, and a US firm to produce a different type of e-diesel and an e-ethanol fuel.
Audi’s next step is to produce more of its new e-diesel – more than 3000 litres over the next few months. It’ll be very interesting to see where things go from there. Perhaps the internal combustion engine isn’t as doomed as some people would have us believe.