Stealth mode: This turbine was fitted with a "stealth" blade last month.
QinetiQ
Coatings and composites ease the air-traffic worries dogging wind power.
Last month Danish wind turbine company Vestas and U.K. defense contractor QinetiQ demonstrated the first "stealth" wind-turbine blade--their solution to the aviation radar interference problem holding up the installation of gigawatts-worth of proposed wind farms worldwide. Vestas composites specialist Steve Appleton says the firm is eager to test a complete stealth turbine and begin limited production by the end of 2010. "Clearly this technology, if proven fully and then adopted by Vestas, would give us a competitive advantage," says Appleton.
Lingering doubts over how stealthy turbines can be, especially when it comes to long-range military radars, are prompting continued research on alternate solutions. Just last month the U.K. government launched an $8.5 million research project with Calgary-based radar system maker Raytheon Canada to make existing air-traffic control systems capable of recognizing and discounting the radar signature from a wind farm.
Wind turbines can interfere with radar in several ways. The turbines can reflect the radar systems' microwave signals, creating a shadow that erases airplanes from radar operators' screens and clutters those screens with the turbines' signature. The signature is also always changing, as blades accelerate and decelerate with the wind, reaching speeds of well over 200 kilometers per hour. Aviation safety and military authorities insist that the potential for confusion and accidents is real.
Such concerns are stalling more than 10 gigawatts of wind power in the United Kingdom. Last year the U.S. Department of Homeland Security commissioned a study on wind power and radar from the JASON Defense Advisory Panel, a science and technology policy advisory group managed by the Mitre Corporation. This study determined that U.S. authorities had halted development of several gigawatts of wind energy over radar concerns, calling it "a serious impediment to the nation's mandated growth of sustainable energy." Radar concerns raised by the U.S. Federal Aviation Administration (FAA) are among the final hurdles holding up Cape Wind from installing 130 turbines in Massachusetts's Nantucket Sound.
The solution offered by QinetiQ and Vestas relies partly on materials analogous to those added to stealth aircraft to absorb some of the radar signal. A five-millimeter coating takes care of the towers, but this coating would add 1,200 kilograms to the large turbine blades. So instead, as was demonstrated in the 44-meter blade installed by the companies on a turbine at a Norfolk, U.K., wind farm last month, two layers of radar-absorbing sheets consisting of glass-reinforced epoxy and plastic foam are laid into the blade's composite structure.
Testing with a mobile radar installation showed that, as expected, the stealth blade produces a markedly smaller signature relative to the turbine's two conventional blades, according to Appleton. He anticipates that subsequent structural testing will confirm that there is no net weight or structural change, since the stealth material simply displaces some of the composite's reinforcing fibers.
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The problem with VAWT is that there is always someone developing them and some people hyping and selling them, but no one is generating usable power from them. They are essentially an idea / concept that when it comes to the engineering and implementation does not provide a sufficient return for the effort and expense.
There is a lot of power generated by VAWTs.
See
http://www.energinet.dk/Integrationer/ElOest/ElsystemetLigeNu/energinet1.swf
and
http://www.eirgrid.com/operations/systemperformancedata/windgeneration/
for two examples.
No power generation is perfect and I think it is important to remove reasons for objections to all the different forms of renewables because in the long run we will need as much variety of generation as possible.
From the article
-quote- Brian Smith, Raytheon Canada's general manager, says the key is teaching the systems to recognize wind turbines as false targets, despite their spinning blades. "As the radar spins, it sends out scans every few seconds," Smith says. "Our solution will use an algorithm in tracker software to say this can't really be a plane, because it's standing still." -unquote-
this cannot be right. It has to be more complex than this. A plane can be stationary, and still be desired to be visible on the radar screen as a plane....
This is really a waste of money. There is not a real concern about this in the aviation community. It comes strictly from wealthy snobs like Robert Kennedy jr who didn't like the idea of windmills spoiling the view from their waterfront mansions. They used this red herring as a way to stop these projects and run up legal costs.
Agreed, this is a non-issue and possibly a smokescreen created by those who lobby against wind turbines or those that don't want to modernise radar systems...
Wind farm dynamics are very predictable. The blades aren't going anywhere, they can turn and spin around at different speeds but that's an easy radar software problem.
A wind farm would actually be a good location for a modern radar system. Put it on top of one of the turbine nacelles, possibly on an elevated tower; the structural requirements are already there, so this saves cost. With more and more windfarms, radar coverage would only improve.
Maybe the need for airplane flying will disappear as the decrease of fuels necessary for flying occurs.
Implementation of new technology in wind turbines
Radar technology helps fight environmental concerns and protects wildlife habitat. It also helps to address other issues connected with wind farms. The efficiency and reliability of the wind turbines is crucial and needs attention. Pacific Crest Transformers is one such company that looks into the generation of wind energy. For more information on wind turbines, check http://www.pacificcresttrans.com/home.html
I think wind power is really interesting and I love this kind of technology but wouldn't life be better if we built a bunch of new nuclear reactors and called it a day?
Dkohn,
About the reactors.... The average nuclear reactor uses 231 million gallons of water a day. So 10 more reactors are going to need 2.3 billion gallons. Where are we going to get the water? MIT Review published an article that suggested we can maybe build 25 more reactors. After that, we are going to have to choose between food, power or showers.
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154 Comments
VAWT's
According to many experts on wind turbines VAWT's do not cause radar interference, plus they can be constructed using less material. The supporting tower in particular can use less material by using high tension support cables. If the cost of wind energy is going to be brought down then all avenues have to be fully explored. It is akin to what is happening in the solar power industry, where all sorts of technologies with differing levels of efficiency are being investigated. VAWT's may have a lower efficiency but that does not mean they aren't as good as HAWT's. SRC Vertical, a Russian company developing VAWT's have plenty of information about this.
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