"Caruso said most growth in energy demand will be in...

"Caruso said most growth in energy demand will be in transportation fuels as consumers in developing countries purchase more vehicles."

WASHINGTON (Reuters) - World oil demand will soar over the next two decades but more slowly than experts expected a year ago because high crude prices will take a toll, the U.S. government's top energy forecasting agency said on Wednesday.

World energy consumption will grow 50 percent by 2030, the Energy Information Administration said in its new annual long-term forecast. It said demand from developing countries would surge 85 percent compared with a 19 percent increase in industrialized countries.

The EIA also said consuming countries will rely more on OPEC because of low production elsewhere.

"We see strong growth in energy consumption," said Guy Caruso, who heads the Energy Department's forecasting arm. "The vast share, majority of that growth will be in the emerging markets," particularly in China and India, he said.

Caruso said most growth in energy demand will be in transportation fuels as consumers in developing countries purchase more vehicles.

World oil demand in 2010 will average 89.2 million barrels per day, the agency predicted, dropping its forecast by 1.5 million bpd from last year due to higher prices.

In China, the oil use forecast was cut 600,000 bpd to 8.8 million bpd. That still would be up 10 percent from demand of 8 million bpd forecast for this year.

The EIA forecast for India's oil demand in 2010 was unchanged at 2.7 million bpd.

The EIA forecast average world oil demand of 112.5 million bpd in 2030, down 5.1 million bpd from last year's estimate. The forecast was cut based on prices predicted last summer, not June's runup in oil to nearly $140 a barrel. Sustained higher prices would cut demand a further 13 million bpd in 2030.

"We do think that over the next 5 to 10 years the high prices will bring on new supplies that will put downward pressure on price," Caruso said. He did not believe prices would drop back to the levels seen in the 1980s and 1990s.

The EIA said more oil consumption and higher coal use to generate electricity will boost emissions of the main global warming gas, carbon dioxide, by 50 percent to more than 42 billion metric tons per year by 2030.

Oil production from non-OPEC countries will not keep up with demand, so consuming nations will rely on the Organization of Petroleum Exporting Countries for more supplies, the EIA said.

The agency shaved 1.1 million barrels per day of production from last year's forecast for non-OPEC oil suppliers in 2010. It now expects production to be 51.8 million bpd that year, up from 49.5 million bpd projected for this year.

OPEC oil output was cut by just 400,000 bpd to 37.4 million bpd for 2010, up from 37.1 million bpd for 2008.

OPEC member countries are expected to boost production capacity, so they will maintain a roughly 43 percent share of total global oil output through 2030.

Saudi Arabia will remain the world's biggest oil producer in 2030, with expected output of 13.7 million bpd -- down sharply from 16.4 million forecast in last year's report.

Higher production from OPEC members Iraq and Venezuela will reduce the need for Saudi Arabia to pump oil, the EIA said.

Russia's output is forecast to be 13.5 million bpd in 2030, up sharply from last year's EIA forecast of 11.5 million bpd. "We're very optimistic about Russia's potential," Caruso said.

However, Saudi oil production in the short term will be higher than forecast last year, averaging 10.5 million bpd in 2010, up 1.6 million bpd. Russia's output is also expected to be up, by some 200,000 bpd, to 10.2 million bpd in 2010, the EIA said.