Freight Transportation Energy Use & Environmental Impacts
Transportation Energy Use
Fuel consumption by transportation mode
Truck fuel consumption declined by 1.7 percent from 2007 to 2018 while truck vehicle-miles traveled increased slightly (less than 1 percent). Fuel use in Class I freight railroads declined by 9.5 percent, from about 4.1 billion gallons to 3.7 billion gallons for the same period.
Energy consumption by select freight transportation modes
In 2018, freight trucks accounted for the lion’s share of freight transportation energy consumption, followed by water, 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 2.7 percent from 7.3 gallons to 7.5 gallons over the 2007 to 2018 period, and total fuel consumption declined slightly as single-unit trucks traveled 20.9 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) remained relatively stable between 2007 and 2018. However, like single-unit trucks, combination truck fuel consumption decreased slightly, as the average miles traveled per vehicle declined by 9.3 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 2007, the energy intensity of trucking has decreased by 25.7 percent while rail has remained relatively stable.
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, since 2000, the rate of NOx emissions from diesel-fueled heavy trucks declined by 79.5 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 1.7 million tons of NOₓ in 2020. 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 2019, NOₓ emissions from gasoline- and diesel-powered single-unit and combination trucks decreased by 71.5 percent, and PM-10 emissions declined by 66.8 percent. By 2030 truck-related NOₓ and PM-10 emissions are projected to decline by 84.6 and 78.2 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 28.3 percent of all greenhouse gases emitted in the United States in 2018, second only to the industrial sector, which produced the largest amount of GHG emissions (28.9 percent).
U.S. transportation sector carbon dioxide (CO2) emissions from fossil fuel combustion by fuel type
The transportation sector is responsible for 36.3 percent of total U.S. CO₂ emissions from fossil fuel combustion in 2018. 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 58.6 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 2018, 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.
U.S. greenhouse gas emissions from domestic freight transportation
Since 2014, total greenhouse gas emissions from both freight and passenger transportation sources have increased. Freight emissions increased at a faster rate, (7.4 percent) than that of passenger (1.5 percent). Between 2014 and 2018, pipeline emissions rose by 24.9 percent followed by commercial aircraft emissions at 15.4 percent, and truck at 7.4 percent. An increase in the volume of freight movements by the pipeline, air, and truck modes contributed to the rise in their emissions between 2014 and 2018. Greenhouse gas emissions from the rail and water modes declined by 6.0 and 7.3 percent, respectively over the same period.
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 2018 vessel-related spills accounted for 62.3 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, 66.1 and 61.6 percent, respectively.
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.