There are four different end-use sectors responsible for energy consumption: transportation, residential, commercial and industrial. In addition, the electric power sector consumes a lot of primary energy that is subsequently used in the other four sectors.
The transportation sector depends on petroleum as the source of more than 90% of its primary energy for moving cars and trucks. The petroleum is mostly consumed in the form of gasoline, diesel, and jet fuel. Petroleum-based fuels are effective for transportation because they have high energy density and are therefore convenient to store on board the vehicle.1For an interesting anecdote about the U.S. Secretary of Energy Stephen Chu discussing the excellent technical performance of petroleum-based fuels, see Chapter 3 of Russell Gold’s book The Boom (New York: Simon and Schuster, 2014).
Source: U.S. Energy Information Administration, Monthly Energy Review
In contrast to the transportation sector’s heavy reliance on a single primary energy source, the electric power sector depends on a more diverse array of fuels, drawing from coal, nuclear, natural gas, and renewable sources. Coal has historically been the most important fuel for the power sector, but as natural gas and renewable prices leveled or dropped in the first two decades of the 21st century, its relative contribution for power generation has dropped. Because of the expense, petroleum is used for very little power generation in countries where other options are available. In the United States and western Europe, petroleum is used primarily as an emergency or backup fuel for the power sector, with the typical exception of distant islands or remote locations.