The Fukushima disaster could lead to a 15 percent fall in world nuclear power generation by 2035 when power demand may rise by 3.1 percent a year, according to a draft copy of the International Energy Agency's 2011 World Energy Outlook.

Following Fukushima, many countries put their nuclear power policies on hold or under review and some, including Germany and Switzerland, opted out of the technology entirely.

The draft, obtained by Reuters ahead of the publication's launch next week, said it had developed a Low Nuclear Case that assesses possible implications for global energy balances of a much smaller role for nuclear power.

The draft was dated July 2011, and the IEA is scheduled to release the publication in London on Wednesday.

In the Low Nuclear Case, the total amount of nuclear power capacity falls from 393 gigawatt (GW) at the start of 2011 to 339 GW in 2035, compared with an increase to 638 GW in the New Policies Scenario, the report said, a drop of around 15 percent.

The report's main scenario is the New Policies Scenario.

The report said its Low Nuclear Case was not a forecast, but is intended to illustrate what a pessimistic view of the prospects for the nuclear power industry might entail.

The share of nuclear power in total generation drops from 13 percent today to just 7 percent in 2035, with implications for energy security, fuel-mix diversity, spending on energy imports and energy-related CO2 emissions.

The report said that Fukushima had shaken the country's energy sector and that the prospects for nuclear power are now much more uncertain than before the Fukushima nuclear accident and that it had greatly increased the uncertainty about the future role of nuclear power in meeting the world's energy needs.

The IEA report said that the drops in nuclear generation caused a rise in oil- and gas-fired power generation.

The incremental demand for oil in Japan's power sector in 2011 is estimated between 150 and 200 thousand barrels per day while demand for LNG (liquefied natural gas) is expected to rise by 11 billion cubic metres (bcm), the report said.

This equalled about 0.2 percent of global oil supplies and 0.4 percent of natural gas supplies, according to the report.

GAS PRICE FORECAST REVISED DOWN

The report said that global energy prices dropped back shortly after the Fukushima-induced rise, and that in the longer-term, it expected natural gas prices to drop.

Our natural gas price assumptions have been revised downwards because of improved prospects for the commercial production of unconventional gas resources, the IEA said.

In its key New Policies Scenario, the report said it expected natural gas prices to reach $12 per million British thermal units (MBtu) in Europe, $14 per MBtu in the Pacific, and $9 per MBtu in North America by 2035.

This compares with 13.3 MBtu, 15.3 MBtu and $10.4 MBtu respectively in the IEA's previous price outlook for 2035.

In the same scenario, the report said it expected world electricity demand to rise from 17,200 terawatt-hours (TWh) in 2009 to almost 31,500 TWh in 2035, at an annual growth rate of 2.3 percent.

The report said that total investment into the power sector between 2011 and 2035 would be $16.8 trillion.

Renewable energy technologies, led by hydropower and wind, account for half of this additional capacity and 60 percent of the investment in power generation, the report said.

The resulting growth in output from renewables is equivalent to 45 percent of the total electricity generation between 2009 and 2035.

The report said it expected non-hydro renewables to generate 16 percent of global electricity in 2035, up from 3 percent in 2009.

Natural gas power generation was expected to remain constant around 22 percent.

The IEA also said it expected steam coal prices to rise to $110 a tonne (in year-2010 dollar value) by 2035, up from an average of $99 a tonne in 2010.

The report said that while it expected coal's share in global power generation to drop by 8 percent to 33 percent, it would remain the largest source of electricity.

CO2 emissions in the power sector increased by over one-fifth between 2009 and 2035, growing more slowly than demand as a result of increased use of low-carbon energy sources and improved plant efficiency.

Prices for carbon allowances within the European Union were expected to rise to 31 euros a tonne by 2020, to 41 euros in 2030, and to 46 euros per tonne by 2035, the report said.

Overall, the report said that energy import bills would rise in line with higher import requirements.

The IEA's full WEO outlook report is due to be published on Wednesday, November 9.

(Editing by William Hardy)