At this month's meeting of the New England Motor Press Association (NEMPA), Simon Godwin of DaimlerChrysler talked about the coming of cleaner diesel engines, enabled by the availability of low-sulfur fuel starting this fall.
While diesels are known for their high torque and fuel efficiency [Ed. Note: I get hybrid-like highway mileage of over 40 mpg with my diesel Passat, a wagon no less.], controlling particulates as well as oxides of nitrogen (NOx) to meet tougher upcoming emissions standards for all 50 states will require not only improved engine combustion processes but "after treatment" as the exhaust leaves the engine. Automotive control electronics will be key for both these stages.
While engine controls are somewhat familiar, the after treatment control, as is done with current diesel engines, will require having the engine run rich periodically to burn off material trapped in a diesel particulate filter (DPF). In highlighting Mercedes BlueTec diesel technology, being phased in for some 2007 U.S. passenger car models, Godwin noted the first such engines will have an improved DPF. The second phase of this deployment incorporates a NOx storage catalyst (NSC), which similar to the DPF has a cycle to burn off the collected oxides.
The ultimate BlueTec 2 engine will skip the NSC and use urea/water injection to react ammonia with the NOxall for a few bucks worth of fluid replenished at every oil change.
Looks like we'll be seeing more options to getting better mileage (and emissions) down the road with clean diesel, hybrid, and improve gasoline power plants in the not to distant futurethanks to chemistry, combustion, and the automotive electronics needed to bring it all together.