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Oil (petroleum)

Diesel Fuel

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Diesel Fuel Basics

Diesel fuel is refined from oil

Diesel fuel tanker truck
Diesel Fuel Tanker Truck

Source: Stock photography (copyrighted)

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 used in diesel engine generators to generate electricity. Most remote villages in Alaska, and in other locations, use diesel generators to supply electricity. Many industrial facilities, large buildings, institutional facilities, hospitals, and electric utilities also 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 for the reduction of 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.

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Uses of Diesel

Freight truck with diesel engine
Tanker in Ushuaia's (Argentina) seaport.

Source: Stock photography (copyrighted)

The inventor of the diesel engine, Rudolf Diesel, originally designed his engine to use coal dust as fuel. He then experimented with vegetable oil (biodiesel) before the petroleum industry began making the product now known as diesel fuel. Most diesel fuel used 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 helped demonstrate the potential value of the diesel engine design. The diesel engine design 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 contains between 18% and 30% more energy per gallon than regular gasoline. Diesel fuel also offers a greater power density than other fuels, so it packs more power per volume.

In 2014, diesel fuel accounted for about 22% of the petroleum fuels consumed by the U.S. transportation sector.

Diesel fuel is used for many tasks

A dirt scooper and loader loading dirt into a dump truck
Dirt scooper and loader, loading dirt in a dumptruck, redepositing dirt for new runway at the Charlotte Int. airport.

Source: Stock photography (copyrighted)

Diesel engines in trucks, trains, boats, and barges help transport nearly all the products people consume. Diesel fuel is commonly used to fuel public buses and school buses.

Diesel fuels most of the farm and construction equipment in the United States. The construction industry depends on the power provided by diesel fuel. Diesel engines are able to do demanding construction work, like lifting steel beams, digging foundations and trenches, drilling wells, paving roads, and moving soil safely and efficiently.

The military uses diesel fuel for 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.

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Diesel and the Environment

Diesel fuel engines are getting cleaner

Diesel fuel (produced 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 developed emission control technologies for new diesel engines.

The front of a semi-trailer truck
the front of a semi truck

Source: Stock photography (copyrighted)

EPA 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. By 2014, all diesel fuel sold in the United States was required to be ULSD fuel.

The EPA also established emissions control standards for diesel-powered highway vehicles for model year 2007 and later. These engines are designed to operate only with ULSD fuel. Using ULSD fuel and advanced exhaust control systems can reduce vehicle particulate emissions by up to 90% and nitrogen compounds (NOx) by 25–50%. ULSD fuel helps reduce emissions in older engines as well.

Even with these advances, diesel fuel still contributes significantly 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 22.4 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.