Anti-windfarm campaigners in East Anglia were dealt a blow last night as an influential report said onshore turbines could supply enough energy to power the entire globe 40 times over.

Anti-windfarm campaigners in East Anglia were dealt a blow last night as an influential report said onshore turbines could supply enough energy to power the entire globe 40 times over.

A host of local pressure groups have sprung up in recent years to resist the march of the masts in rural locations across the county.

Now a team of international scientists has provided new evidence of the potential of wind power to solve the planet's projected power supply shortages.

A study led by Harvard University professor Michael McElroy said a worldwide network of turbines, operating at just one-fifth of their full capacity, would 'easily' meet global electricity demand.

It said a combination of land-based and offshore windfarms could generate 32 times the amount of energy needed in Britain, 16 times the power required for the United States, 18 times the need in China and 180 times the need in Russia.

Campaigners in Norfolk were keen not to argue with the findings of the academic research, but said wind power was 'unreliable' and called for greater investment in other renewable energy sources, including solar, wave and tidal power.

Michael Windridge, a South Norfolk councillor for Hempnall who is opposing a proposed windfarm in the village, said: 'I'm reminded of the old saying: 'No one ever built a windmill if he could build a watermill'.

'Wind derived from onshore turbines will never become a major source of our energy supply for the obvious reason that wind is such an unreliable source of power.

'If wind speed drops from 40mph to 20mph the power output doesn't drop by 50pc: it drops by 87.5pc. At 10mph wind produces only 1.56pc of the power generated by a 40mph wind. What we need is much greater investment in solar, wave and tidal power.'

Brian Kidd, chairman of the group which has fought against turbines at Shipdham and Scarning for more than seven years, said: 'I think these findings are the wrong way to go. Renewable energy should be a mixture of solutions. In this country, wind can never be the whole answer.'

He added: 'There's a price to pay with onshore windfarms, whether financial or to the people who live in the communities where they are built. To think of wind power as a long-term solution is grossly mistaken.'

The study found that in the UK, a combination of land-based and offshore wind farms had the potential to generate 11,000 terawatt hours of electricity per year, based on 2005 figures.

A terawatt hour (TWh) is a unit of energy equal to the amount of work done by one terawatt (a million million watts) in one hour. The figure far outstrips the UK's total consumption of 348.6 terawatt hours.

Currently only a fraction of energy is supplied by wind power, even in the UK which is considered the windiest country in Europe.

In 2007 wind energy overtook hydropower to become Britain's largest renewable generation source. However, it still only contributed 2.2pc of the UK's electricity supply.

The government has set a target of meeting 15pc of all the UK's energy demands from renewables by 2020, which means between 35-45pc of electricity will have to come from green sources. Most of this is expected to be generated by windfarms.

For the study, a team of international scientists divided the world into areas of around 3,300 sq km.

The researchers then obtained six-hourly wind speeds for non-urban, non-forested, non-ice covered regions that would be suitable for windfarms. Further analysis was carried out on offshore sites up to 50 nautical miles out to sea at depths of less than 200 metres.

The scientists worked out the potential for wind power electricity generation based on wind speed, air density, the spacing of turbines, and the size of turbine blades.

Environmental campaign group Friends of the Earth's energy campaigner Nick Rau said: 'This is further evidence of the huge role that wind power can play in cutting climate-changing emissions and meeting our energy requirements.

'The government must reap the economic and environmental rewards from developing green energy by urgently tackling the barriers that prevent wind energy from taking off, and make this country a world leader in developing a clean and prosperous low-carbon economy.'