(From top) Quiet Revolution, the new wind turbine, uses a vertical axis design; an offshore floating turbine; and a magnetic levitation wind power generator

Wind power seems to have arrived. One of the first among renewable energy sources to shrug off the “alternative” tag and enter the mainstream, its per unit production cost is comparable to that of thermal power stations run on natural gas. But designers of windmills haven’t stopped experimenting with new blueprints. While some seek to improve efficiency and thus reduce the cost, others seek to address the controversies associated with this source of clean power, such as the irritating humming sound of the rotating blades and the dangers they pose to birds and bats in and around installations. And there are others who even try to lure the rich by offering aesthetically pleasing wind turbines that can add decor to their dwellings.

India, currently ranked fourth amongst the wind energy producing countries of the world after Germany, Spain and the US, is also expected to benefit from these developments. The country has so far only scratched on the surface of its wind power potential, which is said to be more than 45,000 MW. This potential is more than a third of the current installed capacity from all energy sources in India.

Vertical axis design

Urban settings, it is said, are not suitable for installing a windmill. Some wind turbulence is inevitable unless the turbine is located well above the surrounding buildings. Most of the time, the turbulence from surrounding buildings of different heights will affect a wind turbine to some extent. A British firm, Quiet Revolution Limited, however overcame this problem by opting for a vertical axis wind turbine. This is ideal because it doesn’t require wind from a consistent direction to produce power.

Quiet Revolution — the new wind turbine — is leading the way in urban energy, harnessing wind power in urban environments. “City dwellers and businesses are the biggest users of energy. But ironically, the impact of wind generation has traditionally been focused on rural areas — the regions where least energy is consumed. This brings the debate on wind generation directly into the cities,” says Robert Webb, CEO, Quiet Revolution Ltd. Quiet Revolution turbine’s elegant design is geared towards adding visual appeal to its surroundings, and the aerodynamics of the vertical-axis design mean that noise and vibration are reduced. Most of the urban turbines work at heights less than the conventional height of 50 metres.

Three S-shaped blades are tapered to shed noise. The helical or twisted design captures turbulent winds and eliminates vibration. At five metres in height and three metres in diameter, it is easy to integrate with existing masts and buildings. The blades, spars and torque tube are made of robust carbon fibre, and all moving parts are sealed to minimise maintenance.

This new technology, however, is prohibitively expensive — it costs a little over Rs 25 lakh per unit along with installation. A spokesperson for Quiet Revolution said at a recent Next Fest exhibition in New York that the company is currently in the process of short-listing some Indian manufacturers to lower production and distribution costs by as much as 40 per cent. The company is even considering specific stripped-down versions of this technology for the Indian market at a much lower price. The complete technology is extensively used in the UK with the product being proposed for use with new construction projects, existing buildings and for private homeowners. Building types include commercial buildings, housing projects and public and exhibition buildings while the scale ranges from multi-million pound developments down to individual houses.

Magnetic levitation technology

In Asia, Chinese developers unveiled the world’s first permanent magnetic levitation wind power generator at the Wind Power Asia Exhibition 2006 in Beijing. The device, called MagLev generator, is being regarded as a key breakthrough in the evolution of global wind power technology. It was jointly developed by Guangzhou Energy Research Institute, under China’s Academy of Sciences, and other researchers. The MagLev generator is expected to boost wind energy generating capacity by as much as 20 per cent over traditional wind turbines.

According to the scientists behind the technology, the generator can dramatically lower operational expenses of wind farms by as much as 50 per cent. This is said to drive the cost of wind power to below five cents (US) per kilowatt hour.

Magnetic levitation is a method by which an object is suspended above another object with no support other than magnetic fields. The electromagnetic force is used to counteract the effects of the gravitational force. These wind turbines employ the same technology used in high speed MagLev trains.

The magnetic levitation that they use is between the rotating shaft and the fixed base of the machine, basically taking the place of ball bearings. Making magnetic bearings beefy enough to handle the loads a wind turbine would put on them is hard, and would use prohibitive amounts of power just keeping the electromagnets running strongly enough. This turbine however uses “full-permanent” magnets, meaning there are no electromagnets but only cleverly placed permanent ones, thus doing away with the need for power.

Offshore floating turbines

Taking a cue from such developments, a Massachusetts Institute of Technology researcher has visualised deploying many hundreds of huge offshore wind turbines to provide onshore customers with enough electricity to power several hundred thousand homes, but without being seen by anybody standing onshore. The wind turbines would float on platforms about 150 kilometres into the sea, where the winds are strong and steady.

Today’s offshore wind turbines usually stand on towers driven deep into the ocean floor. But that arrangement works only in water depths of about 15 metres or less. The proposed installations are therefore typically close enough to shore to arouse strong public opposition.