Small is beautiful was once the slogan of the alternative energy movement. But when it comes to wind power, bigger is definitely better. Not only are wind turbines a lot bigger than they were a decade ago, but so too are the deployments. Some critics argue that this large-scale development of wind energy carries too high a price - literally, in terms of subsidies or because of the environmental impact - but in a world worried about fossil fuel prices and global warming, wind energy seems a difficult option to resist. In 2004, almost 8,000 megawatts (MW) of new capacity was installed worldwide, an increase of 20 per cent on 2003. On a good day, wind power contributes 20 per cent or more of electricity generated in leading wind power countries such as Denmark or Spain. "Wind power has hit the big time," says Corin Millais, chief executive of the European Wind Energy Association, which estimates the global wind market could reach $150bn by 2012. The industry's strong growth, initially limited to a handful of countries, looks set to extend globally as more countries wake up to the attractions of wind power in mitigating carbon dioxide emissions and reducing dependence on fossil fuels. Governments around the world have come to realise that wind energy, unlike other green energy contenders, is a mature technology whose commercial development and economic payback are well understood. Even the US has finally got the message - by the end of 2005, 2,000MW will be installed in the country. The next decade will likely see a broadening of the wind energy industry to cover new emerging markets in Europe, South America, north Africa and Asia. Prospects in China look particularly bright. "China has a vast wind resource and an increasing need for electricity," says Robert Gleitz, general manager of GE Energy's wind business. The company recently supplied 23 turbines for a large-scale wind farm in China's Hebei province. Other wind energy companies are also hungrily eyeing the Chinese market. This year, for example, Spain's Gamesa has signed contracts to supply China with 255MW of wind power. By 2020, China wants to produce 20 gigawatts of installed wind power capacity. A new renewable energy law, based on the European model, comes into effect in January and sets favourable tariffs for green energy sources.

Much of the change in attitude is being driven by improvements to technology. As a result, the small-scale pilot projects of a decade ago have given way to big commercial wind farms in which dozens or even hundreds of giant turbines dot the horizon. To satisfy the demand for bigger wind farms, GE Energy recently launched a new generation of 2.5MW and 3MW turbines which can be up to 120 metres high with rotor diameters of up to 94 metres. For offshore locations, it offers a new 3.6MW version with 104-metre diameter rotor blades. However, not everyone welcomes the sight of these monster machines. For four years, a group of inhabitants of Cape Cod, Massachusetts has been fighting the construction of the first offshore wind park in the US. Developers want to build Cape Wind five miles off the coast. The park will consist of 130 GE- supplied wind turbines with a maximum output of 420MW, and the project would produce enough electricity to power three-quarters of the surrounding area with renewable energy and could replace up to 113m gallons of oil a year. However, such arguments hold little sway with opponents, who include prominent environmental campaigner Robert F Kennedy Jr, a marina owner and other well-heeled locals. They say the project will interfere with fishing, pose a hazard to navigation and disrupt tourism. Last month, they took their protests to the seas and heckled a Greenpeace research boat that was giving supporters of wind energy a tour of the proposed site. The environmental activist group has come out strongly in favour of wind power through its Windforce 12 campaign, which wants to see 12 per cent of the world's electricity generated by wind, saving 11bn tonnes of carbon dioxide by 2020. That Greenpeace should be cast as the villain in an environmental battle shows just how divisive and controversial the debate about wind power has become.