7-2 Transportation Energy Consumption by Source: 2013
percent of Btu consumed
| Source | Trillion Btu | Percent | 
|---|---|---|
| Petroleum | 24,873 | 92 | 
| Renewable energy | 1,244 | 5 | 
| Natural gas | 795 | 3 | 
Key: Btu = British thermal unit.
Note: Excludes electricity retail sales and electrical system energy losses.
Source: U.S. Department of Energy, U.S. Energy Information Administration, Monthly Energy Review, available at www.eia.gov/totalenergy/data/monthly as of September 2014.