Diesel Fuel Basics
Diesel fuel is refined from oil
Diesel fuel is used in the diesel engines found in most freight trucks, trains, buses, boats, and farm and construction vehicles. Some cars and small trucks also have diesel engines. Diesel fuel is also used in diesel engine generators to generate electricity. Most remote villages in Alaska, and in many other locations, use diesel generators to supply electricity. Many industrial facilities, large buildings, institutional facilities, hospitals, and electric utilities have diesel generators for backup and emergency power supply.
Diesel fuel is a type of distillate fuel. On average, about 12 to 13 gallons of distillate are produced from each 42-gallon barrel of crude oil in U.S. refineries.
Before 2015, diesel fuel sold in the United States contained high quantities of sulfur. Sulfur in diesel fuel produces air pollution emissions that are harmful to human health. In 2006, the U.S. Environmental Protection Agency issued requirements to reduce the sulfur content of diesel fuel. The requirements phased in over time, beginning with diesel fuel sold for vehicles used on roadways and eventually covering all diesel fuel. All diesel fuel now sold in the United States must have a sulfur content of no more than 15 parts per million.
Uses of Diesel
The inventor of the diesel engine, Rudolf Diesel, originally designed his engine to use coal dust as fuel. He also experimented with vegetable oil (biodiesel) before the petroleum industry began making diesel fuel. Most diesel fuel we use in the United States is refined from crude oil, and diesel fuel is a type of distillate fuel. Biodiesel use is also common.
The first diesel engine automobile trip was completed on January 6, 1930. The nearly 800-mile trip was from Indianapolis, Indiana, to New York City. The trip demonstrated the potential value of the diesel engine design, which has been used in millions of vehicles since its inaugural trip.
Diesel is an important fuel
Diesel fuel is important to the U.S. economy. As a transportation fuel, diesel fuel offers a wide range of performance, efficiency, and safety features. Diesel fuel also has a greater energy density than other liquid fuels, so it provides more useful energy per unit of volume.
In 2016, diesel fuel accounted for about 21% of the petroleum fuels consumed by the U.S. transportation sector.
Diesel fuel is used for many tasks
Diesel engines in trucks, trains, boats, and barges help transport nearly all products people consume. Diesel fuel is commonly used in public buses and school buses.
Diesel fuel powers most of the farm and construction equipment in the United States. The construction industry also depends on the power diesel fuel provides. Diesel engines can do demanding construction work, such as lifting steel beams, digging foundations and trenches, drilling wells, paving roads, and moving soil safely and efficiently.
The U.S. military uses diesel fuel in tanks and trucks because diesel fuel is less flammable and less explosive than other fuels. Diesel engines are also less likely to stall than gasoline-fueled engines.
Diesel fuel is also used in diesel engine generators to generate electricity. Many industrial facilities, large buildings, institutional facilities, hospitals, and electric utilities have diesel generators for backup and emergency power supply. Most remote villages in Alaska use diesel generators for their electricity.
Diesel and the Environment
Diesel fuel engines are getting cleaner
Diesel fuel (refined from crude oil) produces many harmful emissions when it is burned, and diesel-fueled vehicles are major sources of harmful pollutants such as ground-level ozone and particulate matter. To address this problem, the U.S. Environmental Protection Agency (EPA) established standards for the sulfur content of diesel fuel and for emissions from new diesel engines.
EPA fuel standards require a major reduction in the sulfur content of diesel fuels. To meet the EPA standards, the petroleum industry is producing Ultra Low Sulfur Diesel (ULSD) fuel, a cleaner burning diesel fuel containing a maximum 15 parts-per-million (ppm) sulfur. All diesel fuel sold in the United States since 2014 is ULSD fuel.
The EPA also established emissions standards for diesel engine highway vehicles for model year 2007 and later. These engines are designed to operate only with ULSD fuel. Using ULSD fuel and advanced exhaust emission control systems can reduce vehicle particulate emissions by up to 90% and emissions of nitrogen compounds (NOx) by 25%–50%. ULSD fuel helps reduce emissions in older engines as well.
Even with these advances, diesel fuel still contributes to air pollution in the United States because it will take a long time for new cleaner burning diesel vehicles to replace older vehicles.
Carbon dioxide emissions
About 22 pounds of carbon dioxide (CO2) are produced when a gallon of diesel fuel is burned. Carbon dioxide is a greenhouse gas that is linked to global climate change. Diesel engines get better fuel economy than gasoline-powered engines, so the amount of CO2 produced for each mile traveled may be lower in a vehicle with a diesel engine.