Nature's own solutions

There is no such thing as free energy but what nature has to offer comes close.

At first glance, there is no comparison between the small wind turbine that stands on Sir Bani Yas Island and the mighty power station at Jebel Dhana, 250km west of Abu Dhabi city. The first, capable of generating a modest 0.85 megawatts, supplies a small proportion of the electricity needs of the island's 64-room hotel. The Shuweihat plant, the largest of several working hard to satisfy the emirate's escalating power needs, has a capacity of 1,500MW.

Yet as disproportionate as the current contributions of these two energy solutions appears to be, there are those who believe that part of the answer to the climate-change conundrum is blowing in the wind. Among them is Michael Holm of Vestas Wind Systems, a Danish company which has been in the wind-powered electricity generating business for 30 years. "The continent of Europe," he says, "could be powered 100 per cent by wind".

All it would take to tap into one source of carbon-free power, he says, would be for politicians and bureaucrats to get their acts together and invest in grids and wind power: "The grids are out of date because they are very local and you cannot export electricity. To meet current and future energy demand, you need to be able to transport electricity where it is needed ... The wind always blows somewhere and peak hours for electricity are not the same country by country."

The European Union and US are aware of this, says Mr Holm, "but politicians do not get elected for investing in something like the grid". Today, wind power supplies only 1.3 per cent of the planet's electricity, but it does not have to be that way, says Vestas, whose president, Ditlev Engel, is taking part in tomorrow's opening forum at the World Future Energy Summit. In Denmark, turbines generate as much as 20 per cent of the nation's power. Since 2005, worldwide wind-turbine capacity has been increasing at an average of 27 per cent a year; in 2008 alone, the market increased by 42 per cent and global capacity now stands at more than 122,000MW in more than 70 countries.

Vestas, by capacity the world's leading producer, installs a turbine somewhere in the world every three hours; since 1979 it has installed more than 39,000 units. Its customers range from the UAE - the small Sir Bani Yas unit is its only installation in the Emirates - to Germany, its biggest customer, with 5,700 turbines generating more than 7,000MW. Not far behind is India, with more than 4,000. China, currently under scrutiny for the climate-changing effects of its coal-fired power stations and expected to be the world's biggest consumer of electricity by 2030, is also exploring the potential of wind power. Since 1986, Vestas has installed more than 1,700 turbines in China, with a capacity of 1.7 gigawatts. "According to China's own estimates," says Vestas, "the country has a wind potential of 250GW onshore and 750GW offshore, and the potential of becoming the largest global wind market".

Wind power is a technology that favours northern countries, in the same way that solar power has more potential in the south. For example, a turbine capable of generating three megawatts can produce enough power to run an average European household for an entire year in less than three hours. Put another way, it could service more than 3,600 such homes all year round. Building, installing and operating turbines for their estimated lifespan of 20 years does cost a certain amount of electricity, but this is offset in under seven months. Furthermore, compared with a coal-fired plant, in 20 years a wind turbine generating the same amount of electricity will prevent the release of 125,000 tonnes of CO2.

There is no shortage of potential generating power in the tides and currents of the world's oceans but, as with wind power, grid issues hamper widespread exploitation of this free power source. In April 2008, UK-based Marine Current Turbines installed the world's first commercial-scale underwater turbine, a 1.2MW unit at the mouth of Strangford Lough in Northern Ireland, where the average spring tidal current runs at more than seven knots. Registered with the UK electricity regulator as a generating station, SeaGen is connected to the Northern Ireland grid, to which it contributes some five megawatt hours per tide - enough to meet the needs of 1,500 British households.

"Some promising tidal locations either do not have the grid close at hand or the local grid is so weak that there are stability issues if we seek to input a lot of power into it," says Peter Fraenkel, the company's technical director, who takes part in a session on sustainable power at the World Future Energy Summit on Tuesday afternoon. "So the main issue is to have enough grid capacity close to the promising locations."

The company compares its SeaGen turbine to an underwater windmill, only one driven by tides. But similarities end there. One difference is the predictability of the energy source; while wind is unpredictable, tides "are very predictable as they are driven by the movement of the Moon", says Mr Fraenkel. At the moment, tidal energy is reckoned to be about two to three times more expensive than offshore wind generation, but this estimate is based on only one commercial project and the cost is expected to decrease as the technology matures and economies of scale are applied.

"It costs nearly as much to maintain 10 systems as it does to do one," says Mr Fraenkel. However, a major component of the cost is installation. This, in a tide race, "is the most risky and challenging component in our business - the forces we have to withstand during the installation process are the same forces we want to exploit when it is installed and they are very fierce". Although tidal energy can make only "a contribution to future energy needs", he says, "this can be a big and important contribution worth billions per year".

In Britain, for example, which has some of the world's best conditions, tidal energy could contribute between 10 and 15 per cent of the country's total electricity demand.