Transportation
Addressing transportation efficiency both reduces emissions and lessens U.S. dependence on foreign sources of oil.
Two-Fold Strategy Increases Efficiency
The transportation sector is responsible for about 27 percent of U.S. energy consumption and nearly one-third of U.S. carbon dioxide emissions, more than any other end-use sector. Its share of consumption and emissions has grown steadily in recent decades. The transportation industry doesn't only affect the environment. Most petroleum – the main U.S. transportation fuel – is imported, often from volatile regions of the world. Reducing transportation energy use would mitigate climate change and improve local air quality while enhancing our national security and lowering pressure on oil prices.
To reduce energy consumption from the transportation sector, we must address both vehicle fuel efficiency (the energy consumed per mile driven) and fuel conservation (reducing the number of miles driven). Models by the U.S. Department of Energy and environmental think tanks suggest that without policies to address both issues, transportation emissions will continue to rise, making it more difficult for the U.S. to achieve meaningful reductions in carbon emissions.
Dana C. Christensen is Associate Laboratory Director for Energy and Engineering Sciences Directorate at 
