Mercedes Bluetech fuel filler. Click image to enlarge
By Jim Kerr; photo by Bob McHugh
If you think of diesel as a dirty, smelly, smoke-producing fuel, you are in for a big surprise. Today’s Ultra Low Sulphur Diesel fuel (ULSD) looks the same as gasoline and doesn’t have that stereotypical “sulphur” smell associated with older diesel fuels. It also doesn’t produce those clouds of black smoke, because USLD allows manufacturers to build diesel engine emission systems that are as clean as gas engines and more fuel-efficient.
Almost all of a barrel of oil goes into fuel of one type or another. The quality of the crude oil, the impurities it contains, and what is made from it determines the amount and type of refining process used to produce the final product. Gasoline may require more refining than diesel, but that is not always true with ULSD. Removing that sulphur is done with a hydrotreating process that requires heat and pressure in a catalytic cracking tower. Hydrogen is combined with the oil in the presence of molybdenum or cobalt to produce hydrogen sulphide gas. This is then separated from the oil to remove the sulphur.
According to Shell Canada, its ULSD fuel leaves the refinery with about 3 parts per million (ppm). Canadian and U.S. regulations for diesel fuel specify that ULSD have a maximum of 15 ppm sulphur, but Shell says its diesel hits the retail pumps with about 7 ppm sulphur. There is some slight accumulation of sulphur through the delivery process in the pipelines, tankers and trucks. This sulphur level is similar to the 5 ppm level found in European diesel fuels.
ULSD fuel is required in all on-road diesel vehicles built after January 1, 2007. Conventional low sulphur diesel fuels will damage the emissions systems on these vehicles. In 2006, low sulphur diesel fuel typically contained 250 ppm sulphur, even though regulations allowed 500 ppm. Farm diesel fuel is still allowed up to 500 ppm sulphur until 2010, when regulations will drop that sulphur level, but even today, much of the farm diesel fuel is in the 7 ppm range. If you are going to fill your new pickup or car from bulk diesel, be sure to check on the sulphur content first, or you may have expensive repair bills to fix the emission systems.
In the past year, Shell has introduced V-Power diesel fuel. This is a premium diesel fuel specifically produced for today’s sophisticated, high-pressure diesel injection systems. Additives include cetane improvers, de-icers and corrosion inhibitors. Cetane is a rating indicating the ability of the fuel to combust readily when injected. Other fuel companies are also selling premium diesel fuel. Shell’s V-power diesel has about three times the detergent level of the company’s previous premium diesel fuel.
One additive not included with the V-power diesel fuel is an anti-fungal additive. If you mix a little water with diesel fuel and store it in a warm environment, you have created a great setting for growing fungi. If not treated, fungi will plug fuel filters and contaminate fuel tanks. Anti-fungal additives only have a life of about six hours when added to the diesel fuel, and so they are not added at the refinery or at the delivery point. These additives are available at most filling stations that sell diesel fuel, and at all truck stops. It is best added directly into the vehicle’s fuel tank if you are having trouble with plugged fuel filters, or if you have fuel that has been stored for many months and that may have a little water in it.
Currently, the price of diesel fuel is higher than gasoline. This is largely due to the laws of supply and demand. The newest refinery in Canada was built in 1985. Trucking of consumer goods has increased dramatically over the years. If the demand for diesel and gasoline were the same, production costs would mean diesel fuel should be slightly cheaper. Even with diesel more expensive, it does provide about 30 per cent more efficiency. A U.S. gallon of diesel has 134,000 BTU of heat energy, compared to 125,000 BTU for gasoline. Add 10 per cent ethanol to the gas and it is now only 120,000 BTU.
European drivers have embraced ULSD fuel, with most vehicles powered by diesel there. In North America, both the consumers and auto manufacturers are expressing increased interest in having diesel-powered passenger vehicles on our roads. Ultra Low Sulphur Diesel fuel is one of the enabling technologies that will support this.