Posting in Design
With the world on the lookout for nuclear proliferation, proposals for wind turbines in one section of Scotland stand on shaky ground.
North Korea first tested a small nuclear device underground in 2006. The world quickly found out about the explosion, in part due to a network of seismic monitoring stations. Scotland’s Eskdalemuir station is one of those facilities and helps the UK fulfill its obligations to the 1996 Comprehensive Nuclear Test Ban Treaty. The CTBT Commission lists a total of 170 seismic recording stations around the world in their quest to verify any nuclear explosion on Earth.
A potential threat to the Eskdalemuir station’s seismic detection abilities, however, are wind turbines. Whirring on the region’s moors, the large turbines send clean electricity to homes but also send vibrations into the ground.
On Friday, Carlisle Council rejected REG Windpower's proposal for six turbines at a location about 25 miles away from the station. The Hallburn wind farm was also facing local fights over potential lost tourism revenue and noise pollution. But the matter is larger than this relatively small wind project.
The UK’s Ministry of Defence (MOD) established a noise allowance for the region, which they say has been met. According to the MOD, additional wind farms would interfere with the performance of the station’s seismological array. As of now, no turbine with a generating capacity of more than 50 kilowatts is permitted within 31 miles of Eskdalemuir. The company told The Guardian that the MoD’s objections concerning turbine vibrations were blocking as much as one gigawatt of wind generating potential.
Currently across Scotland, the onshore wind industry, according to Scottish Renewables, stands at 2,500 megawatts of installed capacity. Yet growing that capacity in this corner of the Southern Uplands isn't entirely off the table.
In April, the MOD told REG Windpower in a letter:
Calculations are based on current turbine designs. If future technological solutions can be applied to turbines and be scientifically proven to reduce or remove the noise generated, the MOD will reassess its policies.
Matt Partridge, the development director for the company, says they're looking into ways to dampen turbine vibrations. Until then, the future for wind power near Eskdalemuir seems pretty shaky.
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Images: Wikipedia Commons, Flickr/mr_stru
Aug 21, 2011
Minimizing vibration is greatly dependent on dynamic balance of the rotating device at ALL speeds. Every time there is a bird bit it is going to make a minute change in it which over a period of time gets exaggerated. Vertical axis turbines like the ones used in Pearl River Tower project would be far superior. I am quite sure they are a whole lot less "VIBRANT" since they have been installed half way up the office building. These figured can easily be verified on site.
Vertical axis wind turbines are quieter, take up less space, produce less sub-harmonics, and are safer for birds and bats, and best of all are omni-directional.
It's also being researched that the sub-harmonics created by wind generators may react negativly on the human brain. There have been instances where humans living near active wind farms experience high levels of paranoia and aggression. Research seems to indicate that it may be due to the sub-harmonics created by the blades of the wind generators.
Wind turbines are fixed locations, therefore any vibrations can be easily pinpointed as originating at those sites and filtered out. If the nuclear detection folks can't do that, then they aren't worth the money they're being paid. As for the birds dying in the windmills, learn to adapt or die.
The vibration upsetting the seismographic equipment could possibly be filtered out by active filters tuned to the frequency range of the wind generators as these are a known constant. This could be measured over a period of time as soon as each one is installed, existing wind generators could be tested & each signature recorded, making it possible to carry on nuclear monitoring in conjunction with existing other stations without loss of accuracy.
Yes, a vertical turbine does take up less space compared to a conventional one, and is omnidirectional, but I'll take issue with your assessment of noise and safety. I've got a modified (Savonius/Darreius) VAWT with 2.5sqm of sail area on my shed - south coast of the UK - it idles in a 2MPH wind and runs between 200 and 300RPM before the limiter cuts in, somewhere around 60MPH. Even though its composed of polycarbonate sheet on a steel tube frame and weighs very little, it would easily lay me out cold in a light breeze. I will also say I have observed cats and birds to avoid the thing when running, mainly because of the noise it generates. This noise is not from the turbine itself, the bearings make little sound and the wind rushing over the surface also is very quiet, but thats not the issue. As it spins, the cupped blades reflect ambient noise and concentrate it in beams that rotate around it, and it makes an irritating WOWOWOW sound that you also feel if close enough. Its really quite disorientating from a couple of feet away. Also, the relatively large blades block the light, and I can tell if its spinning from inside the house by observing the 1-2Hz flicker in the light through the windows on that side of the house. Its not intense enough to disturb me, but I could imagine someone living close to a farm being driven insane by constant hard shadows from a big one. Just my Tuppenyworth... Peace.
The MOD could very likely put active filtering on the signal, but that also attenuates it, and the signals that are being looked at are already miniscule. Seismographics is more than just a simple recording of a signal - its about comparing the bias of an array of recordings taken from a grid of sensors to see how long its taken for the same signal to get to each one. Its more akin to observing the pattern of ripples on the surface of a bowl of water than it is to recording what vibration caused them. Computers CAN simply reject a certain sequence from a data-stream as easily as an RC network rejects frequencies (and the math is identical), but both would have no usable signal left after removing a local swamp like a wind farm, making the equipment pointless for its expense. The frequencies too, are all sub- to low-hertz, the same as the ones generated and carried by planetary crust, and hard to differentiate between. Extra expense on filtering would also eat into the money saved with the turbines as well from a national viewpoint, so I cant see the MOD changing their minds on that either. Peace
Bat mortality is just yet another one of the dirty little secrets about wind turbines. They kill migrating raptors, too, and they get located in less than optimum areas (with respect to both efficiency and environmental damage) because of politics and corporate greed. Here in the U.S., big subsidies and tax incentives feather corporate nests at the expense of the taxpayer. These industrial monstrosities can be a terrible nuisance to people living nearby and, at least here in the U.S. they do nothing to benefit the environment on account of the so-called "green credits" that they generate, which allow other polluters to pollute more, simply by ponying up some cash to the turbine owners. Just another example of corporate America taking advantage of the well meaning but clueless environmentalists. A tree hugger is no match for a corporate suit when it comes to subterfuge.
I would agree with you based on your description, however what I had in mind was this: http://en.wikipedia.org/wiki/Quietrevolution_wind_turbine
Mine isnt helical, but does use profiled blades to give thrust in two positions while the third blade is being dragged, but it has one point where the leading sail covers the leading edge of the back one, making the torque choppy. The QR is rather nice, but I bet it cost more than mine. 3 Polycarbonate sheets, 3m steel tube, 2 shell bearings and a threaded rod for the 'axle'. What with a few rivets, nuts and some enamel paint the whole lot came in at about 25 quid (under $40). I used a free motor from a scrapped tumbledryer rewound with magnet wire and a few magnets from scrapped microwaves for the genny, but I bought an inverter and recovered a badly sulphated car battery donated by my brother with a conditioner circuit and it gives me 300W, basically runs my workshop. Whats needed is a policy to put well-engineered turbines on tall buildings, where they have the room and the wind, however that would require the power companies either to cooperate or disappear, and THAT is just not going to happen until we stop relying on a token-based economy. One can dream...