World energy demand will grow 50 percent over the next two decades, oil prices could rise to $186 a barrel and coal will remain the biggest source of electricity despite its effect on global warming, US government experts predict.

The Energy Information Administration's long-range forecast to 2030 said the world is not close to abandoning fossil fuels. They will continue to be at the core of energy production in transportation and electricity generation, according to the report released today.

It said the steepest increases in energy use will come in China and other developing economies, including some in the Middle East and Africa, where energy demand is expected to be 85 per cent greater in 2030 than it is today.

"What jumps out is the very strong growth in the emerging economies," said Guy Caruso, the head of the agency that serves as the government statistical and forecasting arm on energy.

Electricity production from nuclear power plants will grow by one-third with the addition of 124 new nuclear power plants by 2030. As many as 45 could be in China, 18 in Russia, 17 in India and 15 in the United States.

The outlook largely assumes no mandatory international agreements on capping greenhouse gases, especially heat-trapping carbon dioxide, which comes from burning fossil fuels. Fossil fuel use "could be altered substantially" by such deals, the report said.

Without such limits, the annual amount of carbon dioxide flowing into the atmosphere would be 51 percent greater in 2030 than it was three years ago, the study said.