Is Diesel Made from Air and Water be a Green?

by Jesse Crabtree

Audi is teaming up with German energy company Sunfire to make fuel for internal-combustion engines and it is literally pulling the fuel out of thin air. This diesel-like substance, called “Blue Crude,” is a string of hydrocarbons formed by combining atmospheric CO2 with hydrogen atoms obtained by water electrolysis. According to Audi, the process produces fuel at an overall efficiency of 70% and is meant to be powered by renewable energy. Furthermore, one of its main draws is that, with the exception of the electrolysis, all of the infrastructure for production and consumption of this product has already been tried and tested. Although it only releases the CO2 initially reclaimed from the atmosphere, the fact that Blue Crude does not totally sequester any emissions gives it a shaky hold on the term ‘green.’ Thus, Blue Crude’s ‘green’ status depends on renewable energies being used to power its electrolysis step. Either way, Blue Crude relies on several important factors—namely low energy prices and new legislation—in order to even be feasible.

Blue Crude requires a large amount of energy during production. Fifty kilowatt-hours of electricity are necessary to produce just one gallon of this new diesel. That is more energy than the average household uses in a day and more than it takes to put 100 miles on a Nissan LEAF: both of which take about 30 kilowatt-hours. Clearly, the economics of producing this fuel are highly dependent on electricity prices. Cognizant of this, Sunfire states that the process can run in reverse—converting the fuel back into power and heat—should energy prices make the process uneconomical. This process would essentially make Blue Crude a fuel-cell like substance and could have further uses for grid balancing and energy storage. These uses seem somewhat secondary however, and make the project highly reliant on lots of cheap electricity that the project’s leaders predict will come from Germany’s new energy policies.

Beyond typical cost considerations, Blue Crude will need help from German legislaters if it wants to compete with fossil fuel prices. As Sunfire CEO Carl Berninghausen puts it, “It’s like comparing a farmer who is growing grain on one farm, while his neighbor simply digs into a huge silo of grain he has discovered on his property. Who do you think will be able to offer the cheapest product?” As such, Blue Crude will need legislative exemption from high energy taxes and possibly other forms of renewable energy subsidies if it wants to sell itself competitively.

Checkered with uncertainty, Blue Crude is a risky investment, but it at least presents a novel way to convert renewable energy into fuel.


Mack, Erick. “Audi Just Created Diesel Fuel from Air and Water.” Gizmag., n.d. Web. 26 Apr. 2015.


Stone, Mike. “Audi Backs an Artificial Fuel Produced by Sunfire’s Power-to-Liquids Process.” Greentech Media, 27 Apr. 2015. Web. 09 Feb. 2016.


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