Of all the environmental boogey men, who would think the diesel engine would be the new green machine? Diesels are clanking, smoking slugs fit only to toil in the slow lane, or so common wisdom has it. But the reality is quite different and has already arrived in desirable form in some very respectable showrooms.
This new reality is based on a triad of new engines, evolving post-combustion clean-up and the fuel itself. Pivotal of the three is the fuel. Thanks to new Ultra Low Sulfur Diesel requirements by the Environmental Protection Agency, the latest engines and clean-up technologies have begat clean diesels powerful enough to retire gasoline hybrids.
How so? For starters diesel is energy dense, packing more energy per pound than any other available fuel, including gasoline. Distilled in the same refineries as gasoline, diesel fuel traditionally has been high in sulfur. But whereas traditional domestic Low Sulfur Diesel is allowed 500 ppm (parts per million) sulfur, the new ULSD mandated in California, Maine, Massachusetts, New York and Vermont last October and nationwide by the EPA by 2010, is allowed 5 ppm sulfur. That's a 97 percent reduction, just a teaspoonful in a tanker truck of fuel.
Practically speaking, ULSD fuel is already the norm. The EPA calls for ULSD at 80 percent of all diesel retail outlets nationwide today, with 100 percent ULSD in 2010. The fuel is already in widespread use and its extra cost of four to five cents per gallon has been absorbed by consumers.
So how exactly is diesel fuel cleaner? Without sulfur, diesel burns cleaner to begin with and several new post-combustion devices can then be used to scrub the exhaust. Simplest of these is a particulate trap. That's a screen in the exhaust pipe which catches what little soot the new crop of advanced engines produce. Oxidation converters are similar to catalytic converters on gasoline engines, but concentrate on oxides of nitrogen, the diesel's emission bug-a-boo.
This new reality is based on a triad of new engines, evolving post-combustion clean-up and the fuel itself. Pivotal of the three is the fuel. Thanks to new Ultra Low Sulfur Diesel requirements by the Environmental Protection Agency, the latest engines and clean-up technologies have begat clean diesels powerful enough to retire gasoline hybrids.
How so? For starters diesel is energy dense, packing more energy per pound than any other available fuel, including gasoline. Distilled in the same refineries as gasoline, diesel fuel traditionally has been high in sulfur. But whereas traditional domestic Low Sulfur Diesel is allowed 500 ppm (parts per million) sulfur, the new ULSD mandated in California, Maine, Massachusetts, New York and Vermont last October and nationwide by the EPA by 2010, is allowed 5 ppm sulfur. That's a 97 percent reduction, just a teaspoonful in a tanker truck of fuel.
Practically speaking, ULSD fuel is already the norm. The EPA calls for ULSD at 80 percent of all diesel retail outlets nationwide today, with 100 percent ULSD in 2010. The fuel is already in widespread use and its extra cost of four to five cents per gallon has been absorbed by consumers.
So how exactly is diesel fuel cleaner? Without sulfur, diesel burns cleaner to begin with and several new post-combustion devices can then be used to scrub the exhaust. Simplest of these is a particulate trap. That's a screen in the exhaust pipe which catches what little soot the new crop of advanced engines produce. Oxidation converters are similar to catalytic converters on gasoline engines, but concentrate on oxides of nitrogen, the diesel's emission bug-a-boo.
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