What is the point of Audi’s (and, in 2007, Peugeot’s) move to diesel power in endurance racing, and why is Shell so centrally involved? If you answered “marketing” you’d be right, though that’s only part of the story. According to Richard Karlstetter, Global Manager, Racing Fuels Technology, Shell Global Solutions (www.shell.com), “The 24 Hours of Le Mans may be only one day, but the engine loads and technology demands are more similar to 150,000 miles for a road-going diesel. What we’re learning is being transitioned back to road fuel development to stretch fuel supplies and lower CO2 emissions.” Notice that Karlstetter isn’t talking about pure alternative fuels, though diesel engines will run on them. That’s because he thinks it’s necessary to produce fuels that can be used in current vehicles without modification.
“Our scenarios indicate conventional crude oil-based fuels will play a significant role over the next 20 years, and only far into the future do we see a point where there is a significant role for non-conventional fuels,” he says. Even taking into account the growth in fuel consumption driven by the developing economies over the next 50 to 100 years, Shell’s scenarios all point to fossil fuels playing a significant role in the transportation sector through 2100. “Gas-to-liquid [GTL] and bio-fuels are the only options that appear viable in the short term,” he says.
That’s why the Le Mans-winning Audi R10 race car runs on a variant of Shell’s commercial “V-Power” diesel, which blends a natural gas-derived GTL component (it has a high cetane rating and minimal sulfur or aromatics) with conventional diesel fuel. However, GTL-enhanced diesel is only one solution. Biomass-to-liquid (BTL) is another. It avoids the major pitfall of first-generation bio-fuels—using food for fuel—by gasifying agricultural waste via the Fischer-Tropsch process used to make GTL fuels. This “syngas” is then liquefied and added to conventional diesel fuel. Unlike GTL production—which is economical only when located near large sources of natural gas, hence the reason behind Shell’s location of its demonstration plant in Malaysia with a commercial-scale plant being built in Qatar—BTL plants can be located anywhere there is a large, sustainable supply of agricultural or forestry waste and a strong diesel market.
The percentage of GTL and BTL in the diesel fuel mix is expected to see its greatest growth as automakers introduce homogenous charge compression ignition (HCCI) engines over the next 20 years. “These engines will need a different fuel that is very clean and of a constant quality,” says Karlstetter. “From today’s perspective, that strongly suggests a diesel bio-fuel.”—CAS