Clean Diesel? Isn't that an oxymoron? If you've ever sat next to a diesel-powered pickup truck at a stop light and had diesel fumes and soot blown in your face from a four inch exhaust pipe, you know what I'm talking about. Traditional diesel engines are about as eco-friendly as a smoke belching coal-fired steam engine from yesteryear.
But diesel technology has advanced considerably in recent years. The latest renditions on Otto's compression ignition engine bear little similarity to the black soot belchers of a decade ago. Common rail high pressure direct injection systems with sophisticated electronic controls have finally tamed the diesel, and made it perfectly acceptable as an alternative to gasoline-powered engines for passenger cars as well as light and medium-duty trucks.
Currently, diesel power-powered cars and light trucks account for less than four percent of the North American vehicle population. The German auto makers are the only ones selling diesel-powered cars in the U.S. Yet in Europe, diesel-powered cars account for nearly 60 percent of the vehicle population.
Why, you ask? Because diesels are up to 30 percent or more fuel efficient than a comparable gasoline engine of the same displacement and horsepower rating. Diesel engines get better mileage because they burn their fuel more efficiently. A diesel engine has a much higher static compression ratio than a gasoline engine, so it achieves more thermal efficiency from the fuel it burns. In other words, it produces less waste heat that goes into the cooling system and out the tailpipe compared to a gasoline-powered engine.
So if we all want better fuel economy, why aren't all the auto makers offering diesel-powered cars? Emission regulations have hampered the sale of diesel-powered cars in the U.S. But now that we have ultra low sulfur diesel fuel available, and new electronic diesel injection technology and after treatment systems, diesels can meet the toughest tailpipe emission standards.
Since 1988, Clean Diesel technology has reduced oxides of nitrogen (NOx) emissions 99 percent, and reduced particulate matter (soot) in the exhaust 98 percent! These are HUGE gains as well as proof of how clean today's diesel engines can actually run.
Green Car of the Year Tour
I recently attended a Clean Diesel event at the Argonne National Laboratory near Chicago, IL. The event was part of the 2010 Green Car of the Year Tour sponsored by the Green Car Journal magazine. The tour included several diesel-powered Volkswagen Jettas TDI models, and the Green Car of the Year winner, the 2010 Audi A3. The Audi A3 gets 42 mpg on the highway with a 2.0L turbodiesel engine, which is 50 percent better than the exact same car with a gasoline engine. All of the vehicles were available for journalists to test drive. My impression? All of the diesel-powered cars started right up, idled smoothly and quietly, and ran great. . . The 2010 clean diesel powered Audi A3 won the Green Car of the Year Award.
If you've never driven one of these state-of-the-art Clean Diesel German cars, I would suggest you do so. You can't tell them from their gasoline -powered counterparts. There's no traditional diesel rattle, no clatter when you step down on the accelerator, no black soot in the exhaust. Just clean, smooth power with lots of low end torque.
A couple of years ago, I also attended an event sponsored by Bosch in Detroit that was promoting their Clean Diesel injection technology. They had a number of European Mercedes and BMW models, some of which were gasoline-powered and some of which were diesel-powered. The badges had been removed from the cars so the journalists couldn't tell which type of engine was powering the vehicle they were driving. I couldn't distinguish any noticeable difference in noise, smell or performance between the diesel-powered cars and the gasoline-powered cars -- which was exactly the point of the demonstration.
Now that Clean Diesel technology is truly available, we will probably see more and more of these vehicles on the road in the years ahead. Proponents of Clean Diesel technology say it can be just as fuel efficient and much more cost effective than hybrid technology.
Argonne Testing Advanced Vehicle Technologies
Argonne is the U.S Dept of Energy's lead laboratory for researching and testing advanced vehicle technologies, including Clean Diesel engines, alternative fuels, hybrid and electric vehicles. The scientists at Argonne are studying and evaluating lots of new technologies to find out how they work, which ones work the best, and what type of fuels offer the best results.This is Argonne's Modular Automotive Technology Testbed (MATT). It is a rolling chassis with interchangeable modules that allow Argonne scientists to test various combinations of powerplants (gasoline or diesel) with hybrid electric drivetrain components on a four wheel chassis dyno.
The German Clean Diesel engines are designed to run on ultra low sulfur diesel fuel, but can also run on B5 (a five percent blend of biodiesel with diesel fuel). Research is being done to determine the suitability of higher biodiesel blends, different types of biofuels, and also diesel-ethanol blends, and diesel-butanol blends (butanol is a different type of alcohol that can also be made from corn, and has less affinity for water, making it better suited for transport through pipelines than ethanol). For more information about butanol, Click Here.
Argonne's scientists are also investigating the possibility of running diesel engines on low octane gasoline as well as other alternative fuels such as natural gas and hydrogen. Agronne's advanced combustion research is looking into the processes that occur inside a diesel combustion chamber when the fuel is injected, mixes with air and ignites. Argonne was the first to document the presence of shock waves that occur during the injection event, which is helping scientists figure out how to optimize combustion efficiency while minimizing the formation of particulate particles (soot).
One of the more advanced fuel projects Argonne is working on is the development of diesel nanofluids. Tiny nanoparticles of metals, oxides, carbides, nitrides or nanotubes are added to diesel fuel to change the way the fuel burns so it will release more heat and energy to improve fuel economy.
Argonne also played a key role in evaluating a number of vehicles that were competing for the Automotive X-prize, the goal of which is to achieve 100 miles per gallon with a production-capable three or four-wheeled car. Is that cool or what?