But fracking has raised environmental concerns. Opponents say drilling fluid or wastewater can seep into water supplies if wells are not constructed properly or if wastewater is not disposed of properly.
Exxon's report predicts that the use of electricity will grow quickly — about 1.3 billion people worldwide do not yet have access to it. But electricity demand in the developed world will remain about flat as devices and appliances get more efficient.
The way electricity will be produced will continue to shift. The use of natural gas, nuclear and renewables will grow and the use of coal will decline. Wind, solar and biofuels will grow the fastest, at 5.8 percent per year. Still, by 2040 they will contribute only 3 percent of the world's energy needs.
The growth in natural gas's contribution to the world energy mix will be the most pronounced, according to Exxon's outlook. This view led Exxon to place a big bet on natural gas when it spent about $31 billion to buy XTO Energy in 2009, a price that analysts now say was much too high. But Exxon's rivals such as Chevron Corp. and Royal Dutch Shell are also leaning more heavily on natural gas.
Still, Exxon says there will be plenty of oil left to power cars, trucks and planes. By 2040 less than half of the world's recoverable oil will have been produced, Exxon's report predicts.