Sweetening the Diesel
Synthetic fuel enhances diesel’s prospects
By KEVIN A. WILSON
AutoWeek | Published 04/18/06, 3:22 pm et
Cute as the headlines are when, say, a fourth-grader makes biodiesel fuel from used French fry oil as a science fair experiment, the reality of global energy demand is such that Mother Earth News subscribers are likely to be disappointed. Tomorrow’s transportation systems won’t depend on do-it-yourself operations—few people will invest the time and effort if they can buy clean, non-petroleum fuels at the corner station.
And whatever you might think of industrial giants like Shell Oil, they are investing heavily to make sure they are still major players regardless of what develops on the petroleum front. Consider the Audi R10 race car that won this year’s Sebring 12 Hour and aims to collect the honors at Le Mans in June. Yes, it’s a diesel, but no, it doesn’t smell bad or spew black junk out its tailpipe. A big part of the reason for that is the fuel, which Shell dubs V-power synthetic in the race car and in the pump version sold to consumers in Germany and the Netherlands.
It doesn’t come from oil, but is an engineered fuel derived from natural gas. Starting with the Fischer-Tropsch process devised in the 1920s to convert coal into liquid fuel (a prospect that alarms environmentalists still today), Shell and other oil companies developed GTL (gas-to-liquid) methods that convert natural gas into not only vehicle fuel, but also engineered lubricants and petrochemical feedstock for the production of plastics. Shell has its own proprietary process. The basics are that it partially oxygenates natural gas to get a blend of carbon monoxide and hydrogen, converts that gas to liquid hydrocarbons, and finally cracks the liquid and refines it into useful products. Other players in this field include Marathon, ConocoPhillips and Sasol Chevron.
At Sebring Audi let us drive on V-power fuel in its new Q7 SUV equipped with a 3.0-liter TDI engine. This V6 is offered in Europe and other markets, but not yet in the United States. The Q7 (“Quintessential Audi,” March 20) provides a quiet, spacious, luxurious ride with quattro all-wheel drive and is Audi’s answer to the likes of the Acura MDX and Lexus RX.
The diesel model makes 233 hp, or about 120 hp less than the 4.2-liter V8 gas engine offered in America now (a 3.6-liter, 280-hp V6 gas engine comes later). On the other hand, the diesel boasts a massive 368 lb-ft of torque down at 1750 rpm—that’s 43 lb-ft more torque than the gas V8 at half the revs. From a stop, such as at a traffic signal, the Q7 TDI gets out of the way in a hurry. The same engine, installed in an A8, collected top honors in its class at the 2004 Challenge Bibendum in Shanghai, China. We drove it on the F1 circuit there, and it accelerated out of corners like nobody’s business.
So if Audi ever decided to take on the Lexus RX 400h for honors in the clean, high-performance SUV segment, it could do worse than to certify the Q7 3.0 TDI for U.S. sale. Given how well the Volkswagen Jetta TDI fared in our highway economy test against the Toyota Prius, we’d recommend Audi hurry. Execs suggest it could happen by 2008, but that Audi needs to develop an after-treatment system to meet strict California emissions standards for diesels (future standards that are the toughest in the world). We expect something like the urea injection system Mercedes-Benz is pioneering.
Before that happens, though, you’ll need cleaner fuel than we get in America, and that day is nearly here. Law mandates low-sulfur diesel appear in retail outlets starting Sept. 1. And that’s where the gas-to-liquid synthetic comes into play. GTL fuel blends nicely with biodiesel or other synthetics derived from recycled plastics, and the dedicated refineries (Shell’s first one is in Qatar) generate fewer pollutants than petroleum refineries. The best part for motorists is these fuels lack not only the malodorous sulfur that contaminates the pollution control systems of the latest clean diesels, but also other aromatics that contribute to the distinctive, offensive scent of diesel fuel. Open a test tube of this stuff and take a whiff and, well, nothing. It doesn’t even smell like stale French fries.