By Jim Kerr
Canadian drivers have something in common with European drivers: we buy more diesel-powered cars than Americans, at least as a percentage of the market. Vehicles like the Volkswagen Jetta, Beetle and Passat TDI have changed the way people thought about diesel engines. These turbocharged direct injection diesels are relatively quiet and peppy engines and deliver excellent fuel economy. Unfortunately, they also create exhaust emissions that affect our environment.
One principle of diesel operation is that there is always an abundance of air in the engine’s combustion chamber and we only add as much fuel as necessary to produce the power we need. Combine this with the high compression ratios used in diesel engines and the higher BTU’s available from diesel as compared to gasoline, and fuel economy is very good. However, all that air in the combustion chamber combines with nitrogen and carbon to form two unwanted gases: NOx (oxides of Nitrogen) and CO2 (carbon dioxide). In 2007, diesel engines will have to meet new emission standards to reduce regulated gases and pollutants such as NOx and Sulphur Dioxide.
Diesel emission standards have been slowly introduced over the past several years and will continue to become more stringent in the future. Every vehicle or engine that is certified by the US EPA, and that is sold concurrently in Canada and the United States, is required to meet
the same emission standards in Canada as in the United States. For light duty trucks and passenger vehicles, the magic date is January 1, 2007. That’s when the levels of NOx and CO2 must be reduced to meet Tier 2 emission standards. Heavy duty vehicles such as the Ford Powerstroke, GM Duramax and Dodge Cummins have a slight reprieve, as standards for those vehicles won’t be fully implemented until 2010.
Why should we be interested in this? Because it may mean that you won’t be able to buy the diesel you want, or the price of diesel vehicles will go up. Currently, only DaimlerChrysler has the technology on vehicles to meet the 2007 emission standards. They call it BlueTec and they have built more than 10,000 large trucks that incorporate this technology in Europe. In North America, Mercedes will offer an E320 BlueTec vehicle for sale and Jeep will have a 2007 Grand Cherokee equipped with a 215-hp 3.0-litre common rail turbo diesel engine. Other vehicles such as the Jeep Liberty diesel and the VW TDI diesel cars won’t have the emissions technology in place in time to meet the January 1, 2007 deadline and won’t be offering vehicles with diesel engines until later. This could take a year or more.
Because the regulations only apply to vehicles built starting January 1, 2007, any vehicles built before that date can be sold without the emissions equipment. Volkswagen is bringing more TDI diesels into the country this year so they can try to meet some of the customer demand next year, but it looks like they may only have a few months supply. It appears there will be a period of time when you won’t be able to buy a TDI diesel, so if you want one, start looking now.
How is DaimlerChrylser meeting the standards? The E320 BlueTec utilizes a NOx absorber-catalyst (NAC) system. Exhaust gas treatment starts with a close-coupled diesel oxidation catalyst (DOC), followed by the Nitrogen Oxides converter, a self-regenerating diesel particulate filter, and an SCR (selective catalytic reduction) catalyst. The after-treatment system reduces NOx by up to 80%.
The trucks DaimlerChrysler are producing in Europe and concept vehicles they have shown in North America are using a slightly different BlueTec technology. These vehicles have a Urea injection system between the oxidation catalyst and the SCR (selective catalytic reduction) catalyst. The Urea (NH3) combines chemically with oxygen and the NOx to form Nitrogen and water (H2O). The Urea injection system must be refilled during routine vehicle maintenance. To meet North American standards, the vehicle must either be disabled or operate so it will be brought in for service if the Urea level is depleted. Therefore, routine maintenance will become even more important.
It’s ironic that at a time in history when Audi has the first ever diesel engine to win the 24 hours of Le Mans race, breaking records for performance and economy, that it may be more difficult to buy a diesel vehicle here. Vehicles of the future will operate on many different fuels. Diesel will be one of them, but those diesels won’t be anything like what we remember of diesels now.