There is an old saying that, in some circumstances, “no news is good news”. It has also been said that; “for the press, good news is not news.” Perhaps this is why Canada’s new Sulphur in Diesel Fuel regulation has had so little media coverage. Effective October 15 2006, the sulphur content of on-road diesel fuel must be 15 parts per million (ppm), a 97 % reduction from the existing standard of 500 ppm. Given the significant number of diesel-powered commercial vehicles on the roads today, this regulation should go a long way to helping reduce air pollution.
In urban areas, big trucks and buses are one of the biggest sources of air pollution. They produce fine particulate soot—diesel soot—a toxic air pollutant linked to asthma and even cancer. The sulphur in diesel fuel is a problem because it was resistant to the use of advanced cleanup technologies.
Low-sulphur fuel, however, enables advanced pollution controls to remove more than 90% of the fine particle soot. And reducing sulphur also enables use of advanced technologies that help eliminate more than 90% of smog-forming nitrogen oxides. The one newspaper report found on this story quoted Shell Canada as saying that, “People should see an improvement in air quality as major users, such as truckers, begin to use the new [ultra-low sulphur diesel (ULSD)] fuel.” In adopting these new standards for diesel fuel, Canada joins the United States in finally meeting European diesel emission standards.
A slight potential downside to this change is that lowering the sulphur content may slightly lower the energy content of the fuel, resulting in marginally higher fuel consumption. Due to the higher per-litre energy content of diesel fuel and also to the great efficiency of the diesel engine, diesel powered vehicles generally get about 40% better mileage than equivalent gasoline engines. On the other hand, diesel produces 15% higher greenhouse gas emissions per liter compared to gasoline. That said, the 40% better fuel economy offsets the higher-per-liter emission of greenhouse gases.
Even though they are more efficient, diesel engines have thus far failed to compete with gasoline engines in the car market. During the late 1970’s, because of the OPEC oil embargo, sales of diesel powered passenger cars increased dramatically but never to the point of seriously challenging gasoline powered cars.
Diesel engines have much higher compression ratios and so tend to be heavier than an equivalent gasoline engine, and more expensive. Because of their weight and compression ratio, diesel engines also accelerate more slowly. Diesel engines must be fuel injected which, in the past, was expensive and less reliable. Diesel engines tend to produce more smoke, "smell funny,” are noisier and vibrate more. Less diesel vehicles also meant less ready availability of diesel fuel, an added discouragement.
There may be an upcoming boost for diesel car sales, with the arrival in the near future of diesel/electric hybrid vehicles – with perhaps 80 miles per gallon or more.