Widening energy demand in the developing world, especially in Asia and Central and South America, will account for much of the growth.

World demand for crude oil is projected to rise 2.2% per year to 242 quadrillion Btu in 2020 (119 million barrels per day); demand growth in developing countries is expected to average 3.3% per year. Projected demand growth for all types of energy is 2.3% per year globally and 3.7% annually in the developing world.

Crude oil is expected to retain its dominant position in relation to other fuels, accounting for 40% of total energy consumption through the forecast period.

The fastest-growing source of energy will be natural gas with consumption expected to soar from 87 quadrillion Btu in 1999 to 169 quadrillion Btu in 2020. Its share of total energy consumption will increase from 23% to 28%. Much of this growth is in response to rising demand for electricity generated by new natural gas-fired turbines, which is driven in turn by environmental, price, and energy-security concerns.

Growth in coal consumption will be much lower at a projected rate of 1.7% per year. Coal’s share of total consumption is projected to continue its recent decline and subside to 20% by 2020. This drop in share occurs despite projected increases in energy use in developing Asia, where coal remains a dominant fuel. Power generation remains the main driver of coal consumption growth, although the fuel is also vital to China's industrial sector.

World nuclear capacity is expected to rise from 350 gigawatts in 2000 to 363 gigawatts in 2010, but then to decline to 359 gigawatts in 2020. Nuclear-generated electricity rises by 4.7% per year through 2020 in the developing nations.

Although renewable energy consumption is expected to increase by over half through the forecast period, its share of total consumption falls from 9% to 8%, constrained by moderate fossil fuel prices.

Higher emissions of carbon dioxide inevitably follow greater use of fossil fuels. Although energy intensity (consumption per dollar of gross domestic product) decreases in most of the world through the forecast period, total emissions are expected to grow faster than in the 1990s, rising from 6.1 billion metric tons carbon equivalent in 1999 to 9.9 billion tons in 2020.