Audi launches synthetic fuels pilot plant in Dresden

In Germany, Audi is active in the development of CO2-neutral, synthetic fuels. The latest project is a pilot plant in Dresden that produces diesel fuel from water, CO2 and green electricity. Audi and its project partners Climeworks and sunfire opened the plant last week.

With this collaboration, Audi and its partners are demonstrating that industrialization of e‑fuels is possible. The pilot plant was officially brought on stream in the presence of Prof. Dr. Johanna Wanka, German Federal Minister for Education and Research, and Dr. Hagen Seifert, Head of Environmental Assessments, Renewable Energies and New Materials at AUDI AG.

The sunfire plant, which operates according to the power-to-liquid principle, requires carbon dioxide, water and electricity as raw materials. The carbon dioxide is extracted 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 conducted at 220 degrees Celsius and a pressure of 25 bar to produce an energetic liquid, made up of hydrocarbon compounds, which is called Blue Crude. This process is up to 70 percent efficient.

As currently built, the pilot plant on the sunfire grounds in Dresden-Reick can produce approximately 160 liters of Blue Crude per day. Nearly 80 percent of that can be converted into synthetic diesel. This fuel – Audi e‑diesel – is free of sulfur and aromatics. It also 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. This means that it can be used as a drop-in fuel.