Getting the best from wind

Wind energy is the most often talked about renewable energy and features in the Government's Low Carbon Industrial Strategy document, recently released. Focus has been, and remains, on the development of more wind farms, both on- and offshore, with larger output wind turbines a parallel target. For example, the US' Clipper Windpower has set up in the UK with the aim of developing a 7.5 MW offshore prototype, which is to be purchased by the UK's Crown Estates. No specific timeline has been given for its development, but suggestions of production by around 2012 are mooted. The interest in yet larger wind turbines, especially for offshore markets, is reflected in Europe's UPWIND project. A major project of the EU 6 Framework Programme, it addresses a wide range of wind energy issues, including upscaling, by evaluating the technical and economic issues in developing wind turbines having 10 and 20 MW capacities. But even as we look ahead to more and bigger, the question, "are we getting the best from existing wind turbines?" is not one that often, if at all, crops up. With a global shortage of turbine manufacturing capacity, perhaps it should. An article in the July/August 2009 issue of Windtech International highlights an American company's efforts in this direction. Leviathan Energy (www.leviathanenergyinc.com) has developed its Wind Energizer concept: a wind deflection device that improves the efficiency of land-based wind turbines by boosting power output by 40 per cent or more for large wind turbines, while at very low wind speeds, the figure can be 100 per cent. As the article underlines, currently an improvement of between 1 to 2 per cent in efficiency for large wind turbines is celebrated. The science behind the patent-pending invention is, says the article, "rather simple". Wind Energizer is, in effect, artificial landscaping – the wind industry already knows that landscape affects turbine power output and this device alters the air circulation before it hits the turbine's blades. Leviathan uses computer fluid dynamics to model airflow – once it has built up a model of the wind farm and the surrounding landscape – and a resulting Wind Energizer deflector is generated. The article in Windtech International goes into lots of detail about this, but the overall efficiency figures already highlighted speak volumes. In addition to this main positive, the Wind Energizer also benefits gearboxes, lengthening their service life and reducing maintenance requirements. This is achieved because the wind velocities hitting the blades are more uniform. Yet another benefit is that, because the device sees a drop in the so-called cut-in speed – the wind speed at which power can be generated – more can be delivered by existing farms, while areas not previously having the potential may now be reconsidered. In fact, it is claimed, Wind Energizer technology means that the wind map of the world "can be redrawn". Leviathan has, it is reported, proved the technology on a small scale, but is now in discussion with early adopters. Whether it will gather any momentum is yet to be seen, but it is claimed that it offers the capability to increase output from renewable energy "many gigawatts faster than any other technology". If the UK Government is serious about 'green' targets, it should take note. First published in Machinery August 2009