The Energy Information Administration, the department's analytical arm, said it expects global energy consumption to increase by 56 percent during the next 30 years because of growth in the developing world.
The EIA said it expects China and India to account for half of the world increase in energy consumption through 2040.
The EIA's assessment corresponds with expectations from the Organization of Petroleum Exporting Countries, which said China and other Asian economies should take on more energy despite a tepid economic outlook.
"Fossil fuels are expected to continue supplying much of the energy used worldwide," the EIA said in a report published Thursday. "Natural gas is the fastest growing fossil fuel in the outlook."
The EIA said global natural gas consumption corresponds with production gains seen from shale and other unconventional deposits.
Natural gas is touted as a cleaner fossil fuel compared with oil and coal. The EIA said coal is still a dominant source of energy, however, for major economies like China's.
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