CO2-neutral synthetic fuels is one direction Audi is aiming its fuel researches.
The German automaker’s latest project is a pilot plant in Dresden that produces diesel fuel from water, CO2 and green electricity. Audi said it opened the plant November 14 with its project partners Climeworks and sunfire.
Audi added with this collaboration, it is, with the help of its partners, demonstrating that industrialization of e-fuels is possible.
The sunfire plant, which operates according to the power-to-liquid principle, said Audi, 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. sunfire explained 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 said to be 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, claims Audi. 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.
Audi continued by stating it is combining two innovative technologies in this project, which is funded in part by the German Federal Ministry for Education and Research and was preceded by a two-year research and preparation phase: CO2 capturing from the ambient air and the power to liquid process for the production of synthetic fuel. Audi added it is the exclusive partner in the automotive industry.
Audi’s activities in the development of CO2 neutral fuels started in 2009. The Audi e gas plant in Werlte, Lower Saxony, produces synthetic methane (Audi e gas) in a comparable manner; Audi said drivers of the Audi A3 Sportback g tron can fill up with it using a special fuel card.
Audi affirmed it is also conducting joint research into the synthetic manufacture of Audi e-gasoline with Global Bioenergies of France; and a joint project with U.S. company Joule is striving to produce the synthetic fuels Audi e-diesel and Audi e ethanol with the help of microorganisms.