Opec believes it will need to produce far less oil over the next 12 years than does the US, creating uncertainty over whether the oil cartel’s members will invest enough to boost production capacity to stop oil prices rising.

The US Energy Information Agency on Wednesday predicted the world would need more than 37m barrels of oil a day from Opec by 2010 and 44.4m b/d in 2020.

But in a concurrent report, Opec said new supply from other regions and biofuels would reduce the need for its oil from 32m b/d today, to 31m b/d in 2012 before it rose again, but only to 35.5m b/d in 2020 – more than 9m b/d less than the EIA expects.

The differing views matter because the long-term forecasts will be one of the main determinants of how much resource-holders invest in future production capacity.

“The oil industry faces great uncertainties over how much to invest,” Opec said in a background paper.

The oil cartel has long argued that consuming countries’ policies to boost car efficiencies and support alternative fuels make it difficult to know how much oil it will have to produce to meet global demand in the longer term.

This thinking is already having an impact. Saudi Arabia, the world’s biggest oil exporter, recently postponed plans to expand its production capacity past the 12.5m b/d it is expected to reach next year, arguing the demand it anticipated did not warrant the investment.

Other Opec countries – most notably Qatar in terms of natural gas – have also put expansion plans on hold as record oil prices have dampened the urgency to boost production.

But these countries are also worried that biofuels will make their oil redundant – in what could be a misplaced fear, as a barrel of ethanol is still far more expensive to produce than a barrel of Middle Eastern oil.

The EIA sees the use of biofuels doubling from 2010 to 2030, to reach 2.7m b/d, rather than the group’s previous estimate of 1.7m b/d. US ethanol production will account for more than half of that increase, the EIA said on Wednesday. Renewable fuels are expected to make up about 8.5 per cent of global energy use by 2030, up from about 7.7 per cent in 2005, the EIA said.

Because of its higher price forecast, the EIA, cut its oil demand figures, with needs reaching 89.2m b/d by 2010, rather than the previous estimated 90.7m. Most of that cut came from outside Opec. Non-Opec oil production estimates in 2010 were reduced to 51.8m b/d, down 1.1m b/d, while Opec’s estimated supply dropped only 400,000 b/d. to 37.4m b/d.

“We do think that over the next five to 10 years the high [oil] prices will bring on new supplies that will put downward pressure on price. But we’re not going back to the historic prices we saw in the 1980s and 1990s,” said Guy Caruso, head of the EIA.