CAR tech: Audi's miracle e-fuel (2013)

Global warming; sky-high oil prices as reserves peak; spiralling crop prices and intense pressure to find fertile land – society faces immense challenges, as it strives to protect the planet and keep our cars on the move. Audi is working on a miracle fuel that could help mitigate these problems, in a facility under construction in the uncompromising, scorching environment of New Mexico, USA. 

Not content with having a range more diverse than London’s World Pride parade, Audi is moving into the fuels business, in partnership with US biotech firm Joule Unlimited. The pair are developing carbon-neutral synthetic fuels, called e-fuels in keeping with Audi’s E-tron eco brand. Large-scale production of e-ethanol begins in May 2013, followed by e-diesel in 2014 and e-petrol in 2015. If the test-bed proves successful, Audi plans to put the fuels on the market within five years.

The secret to creating these e-fuels is an organism called cyanobacteria. ‘They are single-celled organisms measuring a few thousandth of a millimeter, and one of earth’s oldest lifeforms,’ says Reiner Mangold, Audi’s head of sustainable product development.

Joule’s breakthrough is to genetically modify the cyanobacteria’s behaviour, so that when exposed to carbon dioxide, salty waste water and bright sunlight (see diagram top), they grow and produce a continuous stream of hydrocarbons such as ethanol. Remove the water and treat the hydrocarbons, and you create the basis for E85 e-ethanol (85% ethanol/15% gasoline), ready for burning in slightly modified engines. 

Tweak the process by employing a longer molecular chain, and Audi can harvest alkanes, an important constituent of synthetic diesel. Unlike crude-oil-based diesel, e-diesel contains neither sulphur nor aromatic compounds, while combining high purity with excellent combustibility.

The goal is to create e-petrol too, but this is more challenging due to petrol’s more complex chemical structure. Once the processes have been industrialised, all three e-fuels should be significantly cheaper to generate than fossil fuels.

Even though burning higher octane ethanol emits more CO2 than regular fossil fuels, Audi says its e-fuels are carbon neutral. That’s because the CO2 required is harvested from industry or power stations, stopping it entering the atmosphere.

There are other benefits. Ethanol has typically come from biomass like corn, or biowaste like straw. It’s hard to justify turning corn into fuel to burn when millions are starving, while converting straw is energy-intensive and costly. Audi claims its process generates a yield some 10 to 20 times greater than using biomass to make ethanol. Mangold says: ‘If it all works, we will be able to replace truly massive quantities of fossil fuels with renewable fuels, without competing with the production of food.’

Another touch of genius is that the desert wastelands of North Africa and the Middle East would provide the sunny conditions ideal for e-fuels. An area the size of Sicily could house sufficient e-plants to cater for the 15 million or so Audis in the world. Audi has a 2.0-litre TFSI engine that’s ethanol compatible, and more will follow. But any car converted to run on ethanol could use the partnership’s e-ethanol (Sweden, the US and Brazil are the world’s biggest ethanol markets), once Audi has brokered a partnership to supply the fuel. Unlike electric or hydrogen cars, the refuelling network already exists.

The partnership could transform the biofuels world, and take a small step towards weaning the world off crude oil. In the words of Joule’s chief business officer Paul Snaith: ‘Our facility is the first of its kind. Together with Audi, we can achieve a completely new dimension in unlocking the potential of biofuels.’

By Georg Kacher