Diesel engines: environmental impact and control--a critical review introduction.

Diesel engines are widely used to power trucks, buses, passenger cars, locomotives, and ships. These engines power the heavy equipment that plants and harvests crops, tills soil, clears and reshapes land for roads and buildings, and hauls ores from mines to processing centers. Diesel engines generate electricity as portable power sources, peaking units, and emergency backups when line power is out. They are also employed to pump water and fuel at remote locations. Much of our national defense depends on the mobility, portability, and safety provided by diesel engines and fuels. Diesel fuel has a lower vapor pressure than gasoline and rarely ignites at ambient temperatures in the presence of an open flame. Diesel engines are more attractive than gasoline engines because they deliver more power per unit of fuel consumed; have lower emissions of CO2, CO, and hydrocarbons (HCs) for the same energy output; and last longer. Although their initial cost is higher than comparable gasoline engines, their lifetime operating costs are substantially lower. Diesel engines are widely used in passenger cars outside the United States due to differences in fuel pricing policies.