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Wind Farms Can Interfere With Doppler Radar
T Murphy writes "Wind farms can appear like storms or tornadoes on Doppler radar when placed too close to the radar. Tornado alley is a good area for wind farms, and good terrain for the turbines is also ideal for Doppler radar. With many new farms being constructed, the problem is growing. A false tornado warning was issued in Kansas by a computer, although canceled by a meteorologist aware of the problem — there are fears that false positives will grow. Worse would be a tornado ignored as a wind turbine. While meteorologists are trying to work with wind farm owners to shut off the turbines during bad weather, they have no control over the placement or operation of the turbines. Efforts are being made to improve detection technology to avoid further problems."
If only the wind turbines were on stationary towers, then they might be able to map them, and use such a map to inform their interpretation of the radar data.
Nerd rage is the funniest rage.
I'm not sure that you realize the limitations of the radar systems themselves.
The nexrad doppler radar system uses systems designed in the early-mid 80's. Three meter resolution? Try 1km during the best situations.
Two types of control:
Stall Controlled Wind Turbines (Passive) stall controlled wind turbines have the rotor blades bolted onto the hub at a fixed angle. The geometry of the rotor blade profile, however has been aerodynamically designed to ensure that the moment the wind speed becomes too high, it creates turbulence on the side of the rotor blade which is not facing the wind as shown in the picture on the previous page. This stall prevents the lifting force of the rotor blade from acting on the rotor.
Pitch Controlled Wind Turbines On a pitch controlled wind turbine the turbine's electronic controller checks the power output of the turbine several times per second. When the power output becomes too high, it sends an order to the blade pitch mechanism which immediately pitches (turns) the rotor blades slightly out of the wind. Conversely, the blades are turned back into the wind whenever the wind drops again.
Taken from: www.windpower.org/en/tour/wtrb/powerreg.htm
cheap free energy vs pretty pictures of wind on weather.com
Well tornado warnings can, in fact, save lives.
On the Oregon Cost born and raised, On the beach is where I spent most of my days
My question is: how do you "shut down" a wind farm? The wind blows, the windmills turn.
It's called a brake.
This is what slashdot is for, making you aware of complicated technology which you couldn't possibly have heard of from other sources ;-)
You can't take the sky from me...
Wind farms look like tornados on radar --> wind farms and tornados are the same --> wind farms cause tornados
Time to start a panic. Snopes here I come
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For extra credit:
Tornados are a weather event --> all major weather changes are caused by global warming --> wind farms cause global warming
Tornado warnings are extremely vague. Anyone who has spent significant time living in tornado alley can tell you they are routinely ignored. And the new technologies that attempt to pinpoint tornadoes exactly (TVS, VIPIR) aren't as accurate as they're made out to be. False positives are nothing new.
"I assumed blithely that there were no elves out there in the darkness"
IAMFWDWR (I am a meteorologist familiar with Doppler weather radar) and it doesn't worry me at all. There are lots of objects that cause the same types of problems, including rotating radar antennas and buildings.
When a weather radar system is set up the technicians will do a radar survey of the area and then flag areas for the computer (called an RPG, Radar Product Generator) to ignore. For a wind farm they'd look for an area in low scan levels with a high spectrum width and low to zero velocity and tell the RPG to ignore them. If these areas are too far away from the radar, they won't even be noticed by the radar (all scans are pointed slightly "upwards" so even with the lowest scan level something 200 feet tall would not be sensed unless it was within about 4.5 miles of the radar, give or take) unless you have a problem with subrefraction where the radar beam is bent downwards due to atmospheric effects. This would probably be the only time that the situation would cause a false positive and a meteorologist with any amount of common sense is going to investigate the area as it wouldn't be moving at all and would only appear in one or two scan levels.
The automatic warnings generated by a NEXRAD system are helpful, but are nowhere near foolproof. A competent meteorologist will be able to investigate the areas and determine if a weather warning or advisory is warranted within only a few minutes. (generally less than 30 seconds with a proper setup) Detection technology is already in place and easily enacted. Article is ignorance at best, and scaremongering at worst.
Also, AFAIK the turbines shut down at wind speeds >25 m/s / ~55mph
Ah, found it here: Wind turbines start operating at wind speeds of 4 to 5 metres per second (around 10 miles an hour) and reach maximum power output at around 15 metres/second (around 33 miles per hour). At very high wind speeds, i.e. gale force winds, (25 metres/second, 50+ miles/hour) wind turbines shut down.
I hope I didn't brain my damage.
Won't they run backwards when the weather sucks?
You have the right to remain sentient. If you give up the right to remain sentient, you will be elected to public office
Comment removed based on user account deletion
They should just go back to coal-fired nuclear power plants.
Who would win this election: Andrew Weiner vs Andrew Weiner's weiner.
It's not like the turbines are going to be traveling SSE at 30 MPH.
With a strong enough tornado, they just might.
You missed yaw controlled wind turbines - the common system for homebrewed and also the old "patent windmill" designs like classic the water-pumpers. These pivot the tail which makes the mill turn sideways to the wind to reduce power input or even stop the mill.
Many modern homebrew designs use an off-center and tilted tail pivot and a slightly offset turbine axis, plus a couple stops to limit the tail travel (mainly to avoid it hitting the blades). Combined with the weight of the tail this makes the mill automatically yaw-furl in high winds to prevent electrical overheating or overspeed mechanical stresses.
Some homebrewed wind generators, once they're stopped, are sometimes KEPT stopped by shorting the output, whichmakes them act like an electric brake. The blades rotate very slowly and stay in aerodynamic stall. But trying to do that when they're under power in a storm is more likely to burn out the generator than stop the mill. Available power goes up with the CUBE of the windspeed, torque with the square, and heating from current in a permanent-magnet alternator with the FOURTH POWER.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
All of those turbines make pretty decent wind speed/direction instruments, and they're all connected. How much would it cost to rig data feeds from them to the weather data collection system? I mean, if the weather computers are reading a Doppler shift from an area where there are wind farms but the wind turbines are all indicating 80 kph winds in the same direction it's not hard to figure out what's going on. Likewise if they're showing major surface-level wind shear around a vertical axis!
Lacking <sarcasm> tags,
but the blades still rotate in the wind when shutdown
No they don't, otherwise they would start spinnig too fast. and this : http://www.youtube.com/watch?v=7nSB1SdVHqQ would happen. (blade hits the pole)
Yes, I'm left. You have a problem with that?
Newer turbines don't lock the rotor if there is no emergency - they just pitch the blades so that they will not turn the rotor significantly. Therefore, the rotor may actually still rotate (slowly) even when the turbine is shut down.
So a Fox affiliate employee took the opportunity to...
1) Downplay some senseless and sensationalist bit of fear-mongering...
2) While saying something nice about a green technology that suffers from a lot of NIMBYism...
3) And he based it all on solid science and some common sense?
He was fired immediately after, right?
If it's for-profit but free, you're not the customer -- you're the product (e.g., the Slashdot Beta's "audience").
I work for NWS. False alarms are rare. The Mets know where the farms are and the signals are always there. While there is a chance of a mistake in the heat of battle - the duty Mets are usually overloaded with information during a convective event - they don't happen that often. A bigger issue is a farm degrades the performance of the radar around the farm. In other words, if there is weather right around the farm, you can't see it for noise.
... usually as high up as possible (but not too high), in a place that has as few places were the beam is blocked by terrain, where power and limited bandwidth can be had, etc. The studies done in the 1980's usually found that sweet spot, but it has just been taken away.
Here the real threat.
Lawyers for wind farms who know they have a nimby problem know that one of the arguments will be the interference problem. The lawyers have learned that NWS/DOD/FAA (the radars are a tri-agency project) usually leased the land for the radars in the late 1980s/early 1990's for either 20 or 25 years, so the leases are coming up for renewal.
In several recent cases, NWS/DOD/FAA have gone to the land holder to renew the lease only to find out the wind project has already leased the land for twenty years at 5x the rate of the government lease and get a notice the radar needs to be moved.
Now moving a WSR-88D costs upwards of a million bucks. They are VERY large and engineering studies have to be conducted to locate a good location
So the radar could end up being moved at high expense to a not as good location. While the radar is down (there aren't any spares), coverage may not be available.