"Stealth Blades" Get Turbines Under the Radar By Alasdair Cameron, Contributor
November 23, 2011
New technologies are poised to overcome the radar interference concerns that continue to block gigawatts of wind turbine installations.
LONDON -- After many years of research, the search to produce a 'stealth turbine' with low radar reflectivity is now bearing fruit in technical developments that could achieve stealth technology or make it easier to screen out interference from turbines.
In July 2011, when Vestas announced to the International Wind and Radar Forum in Canada that it had successfully tested a full-scale wind turbine utilising stealth technology, this was just the latest step in a long journey to try and unlock the full potential of wind power, and to overcome yet one more obstacle that stands in its way. Around the world, it is estimated that at least 20 GW of wind power is being blocked because of concerns over interference with radar systems, either military or civilian, with particular concern being expressed over the impact that wind farms could have on air traffic control (ATC) systems. In order to overcome these concerns, a series of technology projects have been run, both to find ways of reducing the radar impact of turbines, and to develop forms of radar that can cope with wind farms.
As far as developing stealthy turbines is concerned, this has been pursued first with, for example, the assistance of the UK government, and more recently as a partnership between Vestas and QinetiQ, a company founded to develop technology for military and strategic industries. Beginning with initial studies and computer simulations of the problem and finally graduating to prototype blades and rotors integrating radar absorbing material (RAM), finally these programs now appear to be coming to fruition.
Radar reflective structures
Wind turbines are large structures, and wind farms are large areas of large structures. Combined with their spinning blades and reflective surfaces they can present a significant Radar Cross Section (RCS). Put simply, this means that they show up as large static or twinkling objects on radar screens, obscuring other objects and raising concerns over a possible impact on the safety of air travel. This problem is particularly acute in countries like the UK and the Netherlands, with their limited space for wind farm development and large amount of air traffic. However, while these countries may have the most acute problems, concerns have also been raised in other countries, including the US. As a result, objections have been lodged against a great many wind farms, with some reports suggesting that up to 12 GW are stalled in the UK alone, and many more projects in the US and elsewhere.
This is far ...
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