Conventional crude oil supplies won't keep up with growing global demand in the next 25 years and other fuels from ethanol to liquefied coal and oil from tarsands will be needed to close the gap, says a draft oil industry report.

The draft report by the National Petroleum Council, an advisory group to the U.S. federal government, is unusual in its emphasis on the need for a broad range of supplemental fuels and conservation to meet future petroleum needs.

The council is made up of a cross-section of oil industry executives and other energy experts selected by the energy secretary to advise the department. Its chairman is Lee Raymond, retired chief executive of Exxon Mobil Corp.

The report, titled Facing the Hard Truths about Energy, projected continued growth of conventional global crude oil production but said that it would not be enough to meet demand.

"It's a hard truth that the global supply of oil and natural gas from the conventional sources relied upon historically is unlikely to meet projected 50- to 60-per-cent growth in demand over the next 25 years," says the report.

To bridge the supply-demand gap, the report called for ramping up development of biomass fuels such as ethanol and biodiesel, liquefied coal and unconventional crude oil sources such as oil from tarsands, ultra deep-water areas and shale oil.

And it says conservation will be needed if supplies are to be adequate to meet the growing demand for energy, especially in industrially developing countries such as China and India.

The report called for improvements in auto fuel economy "at the maximum rate possible" although citing no specific fuel economy increases.

Among the "hard truths" about the global energy future outlined in the report is that "an expansion of all economic energy sources will be required" to meet the demand growth.

It also cautioned that curbing carbon dioxide to address global warming will "alter the energy mix, increase energy-related costs" and will require finding ways to scale back the growth in energy demand even more.

Nevertheless, the report said, coal, oil and natural gas will remain indispensable. In 2030, those three fossil fuels will account for the same share of global energy demand, about 85 per cent, as they did in 2000, the report said.

The report cited estimates by the International Energy Agency and the U.S. Energy Information Administration that projected total liquid fuel production of 116 million to 118 million barrels a day by 2030. International oil companies indicated that amount may not be achievable. Today global crude oil production is about 85 million barrels a day.

The report said production estimates varied among companies but averaged only 107 million barrels a day by 2030, suggesting there may be a struggle to meet future demand even if unconventional oil sources and other liquid fuels are taken into account.

-with files from The Associated Press