Diesel: The Familiar Alternative Fuel: Clean diesel a leading emissions control solution

For most of us the phrase "clean diesel" has long been an oxymoron rivaling "jumbo shrimp" and "military intelligence". Just ask anyone stuck behind a line of 18 wheelers in a traffic jam about the smoky, pungent bouquet unleashed by oil burners.

But that was then; this is now. Clean diesel technology is at the forefront of the alternative fuels revolution thanks both to advances in the refinement of the fuel and the technology of the vehicles using it.

For example, today's ultra low sulfur diesel contains 97 percent less sulfur than your father's diesel fuel. This is a critical component of the process, as sulfur compromises the efficiency of exhaust emission control devices.

And just as the move to unleaded gasoline in the 1970s (or 2008 in the case of NASCAR) enabled dramatic advances in emission control technologies for gasoline-powered engines, so the move to clean diesel has sparked advances in emission controls in diesel engines as the diagram of the VW TDI system above attests. State-of-the-art particulate traps can reduce particulate emissions by 80-90 percent, while new catalytic converter technology - such as selective catalytic reduction (SCR) devices and NOx absorbers – focuses on nitrogen oxides and can reduce these emissions by 25-50 percent.

In addition, new fuel injection technologies such as the high-pressure, electronically-controlled unit injectors first introduced in Europe on trucks and buses augment both the cleanliness and efficiency of modern, clean diesel engines. What's more, variable injection timing and advances in combustion chamber configuration and turbocharging have resulted in quieter, better performing diesel-powered vehicles. It's no accident that upwards of 50 percent of new cars sold in Europe are diesel-powered or that the Audi RS10 turbo-charged diesel sportscar has won the past two editions of the 24 Hours of Le Mans.

When you couple the newly "clean" elements of diesel fuel with the fact that diesel engines provide more power and efficiency than gasoline or natural gas-powered internal combustion engines, it's little wonder diesel is emerging as a key component of the alternative energy equation.