3.2 Diesel Fuel

Diesel (or diesel fuel) is a petroleum distillate that is used to fuel compressionignition type combustion engines. Petroleum-derived diesel is composed of about 75% parraffins and cycloparaffins, and about 25% aromatic hydrocarbons, including naphthalenes and alkylbenzenes. In North America, diesel fuel is a popular fuel choice in heavy-duty vehicles such as transport trucks and buses. In Europe, diesel is also popular in passenger cars. In Canada, approximately 16 billion litres of diesel fuel are sold annually, and this volume is increasing.²

Diesel fuel is very similar to the heating oil used in central heating systems. Canada, Europe and the United States place specific taxes on diesel fuel for on-road use, creating significant price differentials compared to heating oil. In many jurisdictions, heating oil is marked with fuel dyes and trace chemicals to prevent its substitution as diesel in on-road applications, and to facilitate detection of the tax fraud if substitution does occur.

Ultra-low sulphur diesel (ULSD) was set by the United State’s EPA as a new standard for the sulphur content in on-road diesel fuel sold in the United States effective October 15, 2006. This new regulation applies to all diesel fuel, diesel fuel additives and distillate fuels blended with diesel for on-road use. The EPA mandated the use of ULSD fuel in model year 2007 and newer highway dieselfuelled engines equipped with advanced emission control systems. Canada also introduced regulations for ULSD implementation in 2006. The requirements of the Canadian regulations were aligned, in level and timing, with those of the United States’ EPA.

Diesel engines are more efficient than gasoline engines of the same power, and as a result, offer lower fuel consumption to vehicle operators. Diesel fuel is denser and contains about 15% more energy by volume. Naturally aspirated diesel engines are heavier than gasoline engines of the same power. The addition of turbochargers and improved materials technology is improving the horsepower to weight ratios of modern diesel engines. The increased fuel economy of the diesel engine over the gasoline engine enables the diesel to produces less carbon dioxide (CO2) per unit of distance.

While diesel engines in North America power primarily heavy-duty and mediumduty trucks and buses, their use is increasing in light-duty vehicle applications. Larger capacity vans and pickup trucks from Ford, GM and Chrysler (usually ¾ ton and larger) are available with diesel engine options. Typically the diesel engine option list price averages $9,000 in pickups and vans. For commercial uses requiring towing, load carrying and other tractive tasks,diesel engines tend to have better torque characteristics than the other fuel options.

There are relatively few diesel-powered light-duty automobiles available in the US and Canada. Offerings are primarily from European manufacturers such as Mercedes and Volkswagen although North American and Japanese manufacturers are in the process of developing diesel offerings in the light-duty vehicle sector.

Automotive emissions from diesel-powered vehicles in North America must now meet the same emissions standards as gasoline vehicles in the same duty classification. The processes that give diesel engines efficient fuel economy also create extra emissions of certain pollutants. High compression ratios and lean air-fuel mixtures produce high combustion temperatures, which in turn create more nitrogen oxides (NOx) and diesel particulate matter (also known as smoke) for release into the atmosphere. While the particulate matter can be controlled with higher injection pressures and particulate filters, the big challenge is limiting NOx (Tier 2 regulations in the US are 0.05 gram per mile of NOx, which is of the 0.40 limit in the European Union). In order to meet the more severe emissions requirements in States such as California, sophisticated after-treatment exhaust systems are required, including the addition of catalysts, particulate filters and urea injection to enable conversion of exhaust gas streams to acceptable emissions levels.

²Statistics Canada - Sales of fuel used for motor vehicles, by province and territory 2002-2006