German car maker 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. According to a
press reelase, Audi and its project partners Climeworks and sunfire opened the
plant on November 14, 2014. With this collaboration, Audi and its partners are
demonstrating that industrialisation 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 release added that 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
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
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 pc 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.
Audi 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 is
the exclusive partner in the automotive industry.
Even before the plant opened, the renowned Cleantech Group
from San Francisco added sunfire GmbH to its list of the 100 most innovative
ecotech companies worldwide, the Global Cleantech 100.
Audi’s activities in the development of CO2-neutral fuels extend beyond the partnership with sunfire, however, and
started back in 2009. The Audi e-gas plant
in Werlte, Lower Saxony, already produces synthetic methane (Audi e-gas) in a comparable manner; drivers of the Audi A3 Sportback g-tron can fill up on it using a special fuel card. Audi 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.
Audi also offers a green electricity solution for the owners of the Audi A3