Freight Transportation Energy Use & Environmental Impacts

Transportation Energy Use  |  Environmental Impacts

Transportation Energy Use

Fuel consumption by transportation mode

Truck fuel consumption increased by 16.5 percent from 2011 to 2021 while truck vehicle-miles traveled increased significantly more (22.4 percent). Fuel use in Class I freight railroads decreased by 16.4 percent, from about 3.7 billion gallons to 3.1 billion gallons for the same period.

Energy consumption by select freight transportation modes

In 2021, freight trucks accounted for the lion’s share of freight transportation energy consumption, followed by pipeline, a distant second.

Single-unit truck fuel consumption and travel

Miles per gallon of single-unit trucks (based on total travel and fuel consumption) increased by about 3.3 percent from 7.3 gallons to 7.5 gallons over the 2011 to 2021 period, and total fuel consumption increased slightly despite single-unit trucks traveling 7.3 percent fewer miles per vehicle.

Combination truck fuel consumption and travel

Miles per gallon for combination trucks (based on average miles traveled and fuel consumption) increased by 5.0 percent between 2011 and 2021. However, like single-unit trucks, combination truck fuel consumption increased by 13.2 percent, despite the average miles traveled per vehicle declining by 6.9 percent.

Energy intensities of domestic freight transportation modes

Energy intensity is the amount of energy used to produce a given level of output or activity, which is measured by vehicle-miles, freight-car-miles, or ton-miles. Since 2010, the energy intensity of trucking has decreased by 3.2 percent while Btu per freight car-mile increased by 5.2 percent and Btu per ton-mile increased by 3.1 percent. 

Transportation Energy Use  |  Environmental Impacts

Environmental Impacts

Estimated U.S. average vehicle emissions rates

Air quality is affected by freight vehicle emissions. Compared with gasoline-fueled cars and trucks, diesel-fueled heavy trucks emit a smaller amount of carbon monoxide (CO) but larger amounts of nitrogen oxides (NOx). However, between 2000 and 2024, the rate of NOx emissions from diesel-fueled heavy trucks declined by 88.8 percent.

Estimated nitrogen oxides (NOx) and particulate matter (PM-10) emissions from single-unit and combination trucks

The U.S. Environmental Protection Agency (EPA) estimates that trucks will produce nearly 953 thousand tons of NOₓ in 2024. Substantial reductions in freight-related NOₓ emissions have been made since the EPA required the use of ultra-low sulfur diesel fuel in heavy-duty trucks and other diesel-powered highway vehicles beginning in 2006. Between 2000 and 2020, NOₓ emissions from gasoline- and diesel-powered single-unit and combination trucks decreased by 80.3percent, and PM-10 emissions declined by 79.5 percent. In 2024 truck-related NOₓ and PM-10 emissions are projected to decline by 84.9 and 83.4 percent, respectively, from 2000 levels.

U.S. greenhouse gas emissions by economic end-use sector

In addition to carbon monoxide, nitrogen oxide, and particulate matter emissions, the transportation sector releases large quantities of greenhouse gases (GHGs), such as carbon dioxide, methane, nitrous oxide, and hydrofluorocarbons.  When emissions from electricity are distributed among end-use sectors, transportation was responsible for about 28.5 percent of all greenhouse gases emitted in the United States in 2021.

U.S. transportation sector carbon dioxide (CO₂) emissions from fossil fuel combustion by fuel type

The transportation sector is responsible for 37 percent of total U.S. CO₂ emissions from fossil fuel combustion in 2022. Carbon dioxide (CO₂) accounts for nearly all of the transportation sector’s greenhouse gas emissions. Almost all of the energy consumed by the sector is petroleum based and includes motor gasoline, diesel fuel, jet fuel, and residual oil. Gasoline-fueled passenger cars and light-duty trucks are responsible for about 55.5 percent of transportation sector CO₂ emissions, while the combustion of diesel fuel in medium- and heavy-duty trucks and jet fuel in aircraft produced much of the rest.
The overall trend, from 1990 to 2022, shows that transportation CO₂ emissions rose in large part to an increase in travel demand that was fueled by population and economic growth, urban sprawl, and periods of low fuel prices. From 2021 to 2022, transportation CO₂ emissions increased 1.5 percent.

U.S. greenhouse gas emissions from domestic freight transportation

Between 1990 and 2021, the percentage growth of greenhouse gas emissions from freight sources was 60 percent. Emissions from passenger sources shrank by about 2 percent from 1990 to 2020, followed by an increase of 11 percent from 2020 to 2021, an overall increase of 8.8 percent from 1990 to 2021. This difference in growth is due largely to the rapid increase in emissions associated with medium- and heavy-duty trucks.

Oil spills in and around U.S. waterways

Water quality is affected by oil spills from vessels and pipelines transporting crude oil and petroleum products and by facilities, such as offshore drilling units and platforms. In 2021 vessel-related spills accounted for 68.6 percent of total gallons spilled. Since 2000 significant reductions were reported in the number of all oil-spill incidents and in the total gallons of oil spilled, 75.8 and 93.1 percent, respectively.

Recommended citation
U.S. Department of Transportation, Bureau of Transportation Statistics, Freight Facts and Figures (Washington, DC: 2019).

Freight Facts and Figures, developed by the Bureau of Transportation Statistics, is a collection of charts and statistical tables about freight transportation in the United States. These interactive visualizations and tables provide a snapshot of freight movement; the extent, condition, and performance of the freight transportation system; the economic implications of freight movement; and the safety, energy, and environmental impacts of freight transportation.

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