Global energy demand is expected to soar 44% over the next two decades, with petroleum still accounting for the biggest share of the world's energy mix, the US government's top energy forecasting agency said.

"The current worldwide economic downturn dampens world demand for energy in the near term, as manufacturing and consumer demand for goods and services slows," the Energy Information Administration (EIA) said in its new forecast to the year 2030.

"In the longer term, with economic recovery anticipated after 2010, most nations return to trend growth in income and energy demand," the EIA said.

As the world economies recover, oil prices will rebound as well. US crude costs are forecast to rise from an average $61 barrel this year, to $110 in 2015 and $130 in 2030, the agency said.

Global oil demand is expected to reach 107 million barrels per day over the next two decades, up from this year's nearly 84 million bpd and accounting for 32% of the world's energy supply by 2030.

Almost 75% of the expected increase in global energy demand through 2030 will occur in developing countries, particularly China, India, Russia and Brazil, the agency said.

Opec will continue to provide 40% of the world's oil supplies during the period.

Biofuels, including ethanol and biodiesel, are expected to reach 5.9 million bpd by 2030, a Reuters report quoted the agency as saying.

The EIA said its long-term forecast does not reflect any efforts the US may take to cut its greenhouse gas emissions or an expected new international agreement to curb greenhouse gases. Such plans affect the global energy mix.

If global climate change laws and policies don't change, world energy-related carbon dioxide emissions will rise a third to 40 billion tonnes a year, the agency said.

The EIA's forecast also predicts that in 2030:

• World production of unconventional petroleum resources, including oil sands, extra-heavy oil and coal-to-liquids, will quadruple to 13.4 million bpd, representing 13% of total global petroleum supplies;
• Iraq's crude oil production will jump from 2 million bpd to 5 million bpd;
• Global natural gas demand will increase by almost 50% to 153 trillion cubic feet;
• Renewable energy will be the fastest growing energy source, making up 11% of global energy supplies.