Technology▼Solutions Will ultraclean diesel fly on U.S. roads?
FORD MOTOR CO.
Consequently, this newly discovered method to avoid forming NOx in the first place is CDC’s biggest poUnder the U.S. EPA’s more stringent tential advantage over the other two ble those in the United States, have tailpipe emission standards being technologies currently under invesdriven the push toward diesel in Euphased in from 2004 to 2009, diesel tigation that are capable of meeting rope, as has the more recent commitment from European governments engines are for the first time required EPA standards. These approaches to reduce CO2, Gray explains. In fact, to meet the same NOx and particulate involve after-treatment devices—inmatter (PM) emission levels as gaso“the European desire to reduce CO2 cluding selective catalytic reduction line engines. So far, three technoloemissions relative to the climateand NOx adsorbers—that control NOx gies have emerged that show promise change issue has actually inhibited in the exhaust system rather than in in meeting the new pollution-control them from requiring diesels to meet the engine. standards. EPA is pinning its hopes the same [more stringent] NOx stanOther CDC features include a hyon one in particular, which it develdards” that the United States is imdraulically intensified fuel system to oped and patented, called clean dieplementing, he adds. lower PM and smoke emissions and sel combustion (CDC). improve engine efficiency; a Showcased in a prototype boost system that increases the engine installed in a Ford Galengine power and efficiency of axy minivan earlier this year, the combustion process, thereby the CDC technology achieved reducing emissions and increas30–40% better mileage than ing fuel economy; low-pressure a gasoline minivan, while exhaust gas recirculation, which meet ing EPA’s tier 2 NOx stanlowers the peak combustion temperature to reduce NOx fordard of 0.07 grams per mile for light passenger vehicles, mation; and PM after treatment, according to EPA researchwhich reduces the remaining ers. The CDC technology ensmoke, unburned hydrocarcompasses a series of engine bons, and carbon monoxide in design changes that decrease the exhaust to levels required NOx emissions while mainunder the standards being taining or improving engine phased in. efficiency. EPA and Ford MoDick Baker, a technical spetor Co. are still examining its cialist in Ford’s research and commercial viability. advanced engineering diviThis better fuel economy sion, says that Ford is pleased A new diesel engine design being tested in this Ford with the research and road—typically an improvement Galaxy minivan could help consumers cash in on diesel’s test results so far. He adds that of 25–40%—is a major adsuperior fuel economy while minimizing the noxious emisthe company is eyeing the vantage of diesel engines over sions that diesel is otherwise known for. CDC technology for near-term conventional gasoline en“We felt we could have both,” Gray application in its heavy-duty truck gines. In addition, diesel has lower notes, “and we believe this new [CDC] segment, as EPA’s tailpipe regulations CO2 emissions and higher levels of technology will demonstrate both.” for these vehicles kick in in 2007, and power. These benefits explain why The key concept behind CDC is possibly in its light-duty pickup and there’s so much interest in diesel of the development of in-cylinder NOx sport utility vehicle lines. late, says Charles Gray, director of In phase 2 of EPA and Ford’s coEPA’s Advanced Technology Division control, whereby NOx emissions are operative R&D agreement, researchin the Office of Transportation and reduced in the engine combustion ers will be exploring ways to optimize Air Quality. chamber without penalizing the enthe combustion process in other enCurrently, less than 1% of U.S. gine’s efficiency. Diesels traditiongine types and sizes. But, “if it folpassenger vehicles are diesel-powally have had the most difficulties lows through like our initial results ered, according to EPA statistics. In in meeting NOx emission standards indicate, CDC should be a major sucEurope, however, average market “because they run with an excess cess story for companies that are out penetration stands at 40–50%, with amount of oxygen, so you can’t easily some countries above 50%. in front with this approach,” Gray reduce back to nitrogen and oxygen,” Fuel prices, still more than doupredicts. —KRIS CHRISTEN Gray explains. 238A ■ ENVIRONMENTAL SCIENCE & TECHNOLOGY / JUNE 1, 2005
© 2005 American Chemical Society
