Audi has opened a pilot plant in Dresden that produces diesel fuel from water, carbon dioxide and green electricity. The plant was developed with its project partners Climeworks and sunfire.
The sunfire plant demonstrates that it’s possible to produce e-fuels on an industrial level. The plant, which requires carbon dioxide, water and electricity as raw materials, extracts the carbon dioxide directly from the ambient air using direct air capturing – a technology developed by Swiss partner Climeworks.
In a separate process, an electrolysis unit powered with green electricity splits water into hydrogen and oxygen. The hydrogen is then reacted with the carbon dioxide in two chemical processes to produce an energetic liquid made up of hydrocarbon compounds, which is called Blue Crude. This process is up to 70 per cent efficient.
As currently built, the pilot plant on the sunfire grounds in Dresden-Reick can produce approximately 160 litres of Blue Crude per day – nearly 80 per cent of which can be converted into synthetic diesel. This fuel – called Audi e-diesel – is free of sulphur and aromatics, and has a high cetane number, which means that it ignites very easily. Its chemical properties allow it to be blended in any ratio with fossil diesel, which means it can be used as a drop-in fuel.
Even before the plant opened, the Cleantech Group from San Francisco added sunfire GmbH to its list of the 100 most innovative ecotech companies worldwide, the Global Cleantech 100.