Audi’s Synthetic e-Diesel, a Drop-in Replacement for Diesel B

The efficiency of the overall process is around 70 percent.

Wayne Gerdes - CleanMPG - April 23, 2015

2015 Audi A3 TDI – Someday we may be driving this almost GHG and SMOG forming emissions free with no sacrifice in performance or efficiency.

While most jockey around electrification for the future of mobility, Audi continues down multiple paths. One of the most promising is efficient and energy dense e-diesel.

A pilot plant in Dresden has started production of a CO2-neutral synthetic fuel called Audi e-diesel.

The Audi e-Diesel Story

Just four months after completion, Sunfire an Energy technology company produced its first useable batches of high-quality diesel fuel at its research facility in Dresden. To demonstrate everyday suitability, Germany’s Federal Minister of Education and Research, Prof. Dr. Johanna Wanka, put the first one and third gallons of e-Diesel into her own Audi A8 3.0L TDI quattro.

Sunfire operates the facility on the power-to-liquid (PtL) principle and uses green power to produce liquid fuels. The only raw materials needed are water and CO2!

Most of the CO2 used is supplied by a nearby biogas facility with a small amount being extracted from ambient air by means of something Climeworks, a Zurich-based Audi technology partner, calls direct air capturing.

Reiner Mangold, Head of Sustainable Product Development at Audi:

Quote:

“In developing Audi e-diesel we are promoting another fuel based on CO2 that will allow long-distance mobility with virtually no impact on the climate. Using CO2 as a raw material represents an opportunity not just for the automotive industry in Germany, but also to transfer the principle to other sectors and countries.”

e-Diesel Production Process

Audi e-diesel creation involves water being heated up to form steam which is broken down into H2 and O2 by high-temperature electrolysis. This process involves heating the contained water to more than 1,450 degrees Fahrenheit. Once the molecules are split, the H2 reacts with the CO2 in synthesis reactors at high temperature and pressure. The product is a liquid of long-chain hydrocarbon compounds called blue crude. The efficiency of the overall process – from renewable power to liquid hydrocarbon is around 70 percent. Similar to a fossil crude oil, blue crude can be refined to yield the end product Audi e-diesel. This synthetic fuel is free from sulfur and aromatic hydrocarbons, and has a high cetane number. Audi lab tests indicate it is suitable for mixing with fossil diesel or can be used as diesel fuel directly.

The Sunfire project started in May 2012 with construction kicked off in July 2013. The facility was commissioned on November 14, 2014. While still in pilot plant production status, Sunfire is expected to produce over 790 gallons of Audi e-diesel over the coming months.

The Audi e-gas plant in Werlte, Lower Saxony, already produces Audi e-gas (synthetic methane) in a comparable manner.

Audi is also conducting joint research into the synthetic manufacture of Audi e-gasoline with Global Bioenergies, of France and the U.S. Company Joule in Hobbs, NM. Both use microorganisms to produce the synthetic fuels Audi e-diesel and Audi e-ethanol.

I hope the process can be scaled. If so, one more magic bullet has been loaded into the gun.

Audi’s Synthetic e-Diesel, a Drop-in Replacement for Diesel B