Audi’s Blue Crude: Lingering Questions

Mimi Reichenbach


Update from Germany: Carbon dioxide has become an alternative fuel source.

On April 21, Audi announced that its partner Sunfire, a German energy-conversion technology developer, had successfully synthesized a batch of “blue crude.” The fuel is derived from carbon dioxide, water, and renewable energy, and can be used as (and mixed with) diesel fuel today.

The production process reacts hydrogen (via electrolysis; source: water) and carbon dioxide;  the end product is a hydrocarbon liquid. While the process involves consuming large amounts of electricity to achieve extreme temperatures and pressure, the input energy is all renewably derived. A nearby biogas plant currently supplies the most of the carbon dioxide reactant, but a small amount is also supplied by Climeworks, another Audi partner.  Climeworks technology captures carbon dioxide from ambient air.  The production is still in pilot mode, with a current production capacity of 42 gallons per day in the Dresden, Germany plant.

So is blue crude the new Carbon Capture and Storage (CCS)?  Will driving become part of the climate change solution?

While it would be nice to think that each additional mile on the odometer was playing a role in decreasing global carbon dioxide concentrations, important questions remain unanswered. Mainly: scale, energy costs, and financial viability, along with water use.

Supplying 42 gallons of blue crude daily is not going to disrupt the automobile industry, but Sunfire CTO Christian von Olshausen has said that an upgraded plant will be in the works if blue crude commercialization looks likely.

For a larger plant to be worthwhile, blue crude production must be financially viable. Audi has announced that the expected price per liter will be between 1 and 1.50 euros, which is comparable to current diesel pricing in Germany. In American terms, the equivalent range is 4.24 to 6.36 dollars per gallon.

Will blue crude make it to the States? Since 2011, diesel in the United States has broken the four-dollar threshold several times; yet recently diesel pricing has fallen to below 3 dollars, making it questionable whether blue crude will arrive in the United States.  Yet, if a carbon tax (preferably revenue neutral) were to be implemented, blue crude might be economically realistic.

Writers who follow fuel have been skeptical of blue crude’s technological foundation. Robert Rapier of Greentech Media has declared the process an energy sink.  Vaughn Highfield of PC Pro thinks renewable energy would be better off directly powering sources, rather than synthesizing fuel.  And there is the market to consider as well—Highfield questions whether there is a limited the window of opportunity for blue crude as the popularity of electric vehicles continues to rise.

Still unanswered is how much water is used in producing a gallon of blue crude. It takes 1 to 2.5 gallons of water to refine traditional gasoline; a unit of comparison for blue crude would be welcome, as well as identification of the water source. While 42 gallons a day is not worrisome, if the technology were to increase in scale, water consumption and usage should be carefully considered.

Whether blue crude is successful or not in becoming the gas of the future, the technology is a remarkable advancement in the automotive industry. Germany’s Federal Minister of Education and Research, Johanna Wanka, put some of it in her own Audi, and acclaimed blue crude “a crucial contribution to climate protection and the efficient use of resources.”

Blue crude certainly would be a welcome addition in many diesel engines today. The fuel is quieter than diesel and also boasts a higher energy efficiency of 70%; traditional diesel efficiency remains in the high 40% range.

Most importantly Audi, Sunfire, and Climeworks are demonstrating what is possible in the clean tech space with collaboration. Worldwide, transportation accounts for 13% of global greenhouse gas emissions.  It is remarkable to think that blue crude, a synthetic photosynthesis if you will, would work to reduce carbon dioxide rather than create it. The fuel synthesis marks an incredible achievement and milestone.

If blue crude could work to reverse carbon dioxide emissions in the future, it would be powerful indeed.














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