Diesel fuel explained 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 that contains a maximum sulfur concentration of 15 parts-per-million (ppm). Most of the diesel fuel now sold in the United States for use in vehicles 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% to 50%. ULSD fuel helps reduce emissions in older engines as well.

Even with these advances, diesel fuel use still contributes to air pollution in the United States because it will take a long time for newer and cleaner diesel engine vehicles to replace older diesel engine vehicles.

Carbon dioxide (CO₂) emissions

In 2022, diesel (distillate) fuel consumption accounted for about 25% (464 million metric tons) of total U.S. transportation sector CO₂ emissions and about 10% of total U.S. energy-related CO₂ emissions.

Last updated: March 14, 2024.