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Japan rethinks wind power

Although Europe is a vast, sprawling continent bursting with innovation, our Asian cousins are old hands at taking a sideways look at the world – as these ingenious turbines from Japan clearly illustrate. At the recent Yokohama Renewable Energy Exhibition, Japanese technology threw-up some exciting developments for the sector, including this revolutionary turbine system that could turn wind energy production on its head.

At the end of 2009, the worldwide capacity of wind power generators stood at 159.2 gigawatts, generating 340 TWh per annum (equivalent to about 2% of worldwide electricity usage), according the World Wind Energy Association’s annual report. Much of the potential increase in renewable energy around the world can come from wind but significant investments will need to be made, including in offshore wind farms.

To cope with various social, meteorological and topographical situations, wind technology has developed much over the years. Notable steps are the growth in the size of rotors, allowing a higher volume of electricity to be generated; the installation of variable-speed turbines with rotors capable of handling increases and decreases in wind speed, thus mitigating power fluctuation and noise pollution; and construction of offshore floating turbines to harness consistent and strong winds, some of which are now, at pilot stage, capable of producing 5.0 megawatts of electricity.

At the Yokohama Exhibition, one of the most noteworthy advances in wind technology, the Wind Lens, has already seen the light of day. The name derives from the lens of a magnifying glass because, in the same way that a magnifying glass can intensify light from the sun, wind lenses concentrate the flow of wind. The structure of the wind lens is relatively simple; a large hoop, called a brimmed diffuser, intensifies wind blows to rotate the turbine located in the centre.

Verification experiments show that wind lens turbines produce three times as much electricity as those without a hoop. According to Professor Yuji Ohya from Kyushu University, even a gentle breeze can accelerate the revolution of the turbines considerably. The 2.5 metre-wide blades can, at with wind speed of five metres a second, can provide a sufficient amount of electricity to power an average household.


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