Diesel fuel is not strictly speaking an alternative fuel. However, in North America diesel (or compression ignition) engines are very uncommon in powering passenger vehicles. This is probably due to the poorly-built engines that North American automobile manufacturers introduced during the fuel crisis of the 1970's. Those engines were spark ignition (SI) engines converted to compression ignition (CI) rather than purpose-built compression ignition engines. The motoring public experienced failure-prone low performance engines and have stayed away ever since. Even the European manufacturers did not make a smooth running diesel engine at that time. As North American consumers were used to smooth running powerful gasoline engines, the smoke and diesel clatter did not help to convince these consumers to give these engines a chance.
Times have changed. With the new millennium, automobile manufacturers (especially the Europeans) have been refining the compression ignition engine. There are not very many diesel-powered passenger cars available in North America, but Volkswagen, BMW, and Mercedes-Benz are several manufacturers that come to mind. For light trucks, most manufacturers offer a diesel option because of the strong low speed torque, fuel economy, and long term ease of maintenance (fuel and air filters only, no spark plugs or ignition systems).
For those people having diesel-powered vehicles, a new renewal fuel source is emerging. Biodiesel is made primarily either from animal or vegetable oils. In Canada, biodiesel is being made from soybean oil, canola oil, and mustard oil as those crops are produced in great abundance in its prairie provinces. Biodiesel is also made from animal fats and recycled cooking oil. Biodiesel can be used by itself (B100) but is more commonly blended 20% (B20) with petroleum-based oil. A great deal of research is going into the development of fuel from mustard oils in particular. A side benefit of this crop is that the mustard pulp can then be used as a natural pesticide.
Compression Ignition Engines may be supplied by gaseous fuel like propane or natural gas simulataneously with diesel fuel. The energy provided by the supplementary gaseous fuel offsets the diesel fuel being consumed. Besides reducing particulate emissions, this method of operation can reduce the operating cost of a diesel engine if the cost/kJ (or cost/BTU) of the gaseous fuel is lower than the cost of diesel fuel. This is quite possible, especically with pipeline natural gas and, to a lesser degree, with compressed natural gas. See our Diesel Dual Fuel Conversions page for more information.