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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."
Of course the turbulence will look like tornadoes, but can't they adjust the sensitivity to "if vortex 3m ignore" Or set them to scan Higher then 100m Or whatever the tallest turbine is in that region?
"The price good men pay for indifference to public affairs is to be ruled by evil men." ~Plato (427-347 BC)
Simple solution - pan/tilt/zoom IP-based cameras placed within each wind farm where we can actually SEE if there's an oncoming tornado, etc. Very small investment considering the cost of the actual wind farm itself. Welcome to the new millenium.
"To err is human, to mod Funny divine."
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.
Wind speeds above the maximum design speed will tear the mechanical gearing apart - that is if the wind surfaces don't rip off first.
Most wind turbines already automatically lock themselves when wind speeds exceed certain design specifications to protect themselves from damage.
I am not a meteorologist, but don't tornadoes occur because there is a horizontal boundary between two different types of air masses, and the tornado acts as a funnel to equalize the pressure between the two or something? Maybe wind turbines, and the mixed and turbulence they cause actually prevent tornadoes. Who knows? And, don't many tornadoes occur over particularly flat land? The turbines might reshape the landscape enough to disturb the atmosphere enough to prevent them. Turbines looking like tornadoes on radar make me think i'm not totally crazy.
You turn the wings of the wind wheel so the resulting force is zero.
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
/
/
For extra credit:
Tornados are a weather event --> all major weather changes are caused by global warming --> wind farms cause global warming
All electricity-generating windmills have adjustable-pitch blades.
Power stations can't just produce as much power as they feel like, since electricity can't practically be stored. It has to be used up within about one second of hitting the grid, and if the demand is not there, you need to be shutting down generators.
To deal with this, windmills have adjustable blades so they can extract a variable amount of energy from the wind.
In severe weather, modern windmills are set up to constantly adjust the pitch in response to varying winds just to minimize the excess load on the blades and spine. This is no different that a pilot flying through turbulent air constantly steering the aircraft to minimized the shaking and stress on the airframe.
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.
The United Kingdom military has had to stop the development of some wind farms because it would leave a blind spot to their early warning systems. Their government has doled out a fair bit of cash to find a solution to the issue.
Wind turbines should have a more or less predictable (and hence, recognizable) radar signature. IIRC the US military use turbine signatures (of aircraft engines) as part of non-cooperative target recognition (NCTR), i.e. the ability to recognize the aircraft type from a radar return, without having to rely on IFF transponders. But this probably requires better radars and processing than Nexrad can provide.
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
If the tornado is occurring where the wind farm is, it's the turbines.
If the tornado is occurring where the wind farm is, and the electricity goes out, it's not the turbines.
It'd be a damn shame with all this great technology and great problems to solve if they had to rely on a phone call to a guy at the wind farm who had to look out the window for them in order to know whether there was a tornado or not.
"I may be synthetic, but I'm not stupid." -- Bishop 341-B
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
http://radar.weather.gov/radar.php?rid=buf&product=N0R&overlay=11101111&loop=no Perfect example, if you look at the National Weather Service radar for Buffalo, southeast of the "o" in Buffalo you'll see an orange strip, there are about 100 windmills on hills about 25-30 miles from the airport weather station reflecting the Doppler back.
Put simple wind speed sensors (and other weather reporting gizmos) at each big wind tower, have them automatically update that info upstream so it can be cross referenced. If the remote radar says tornado in the direction of a tower, but the tower only reports a 40 mile an hour wind...you can nail the false positives easier. Turn a liability into thousands of new weather reporting assets.
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,
Recent advances in giant batteries for wind power load balancing: http://www.reuters.com/article/GCA-GreenBusiness/idUSTRE57P4PJ20090826
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").
Have these wind turbines registered with the National Weather Service and mark the locations in the system. Also, place transponders on the turbines to verify their operational status. If a tornado is detected near a known turbine location and the turbine fails to report its status, there probably is "something" in the area bad enough to damage a turbine.
8==8 Bones 8==8
Buildings cause the same problem; anyone familiar with coherence and/or constructive and destructive interference of electromagnetic waves (or any other type of other wave) would say "No sh*t, Sherlock!"
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.
For many years I lived on a sailboat with a wind generator which shorted the output to stop the blades as well as to KEEP them stopped.
Worked fine even in gale force +++ winds.
One VERY dark night headed for Fiji though a magnet came loose in the generator and THAT was spectacular!
Think a 1/2 inch hardened steel rod with a 45 degree bend before it broke!
I now understand that the bade was close to MACH 1 when it broke free!
THANK CTHULU that the flying blade that flew off didn't hit anyone on board but went into the Pacific Ocean! My abject apologies to any fish ...
The CUBE relationship is the biggest problem with wind power - 99% of the time you have to eke out every watt, but for that 1% you have SO much power that it destroys things.
Especially at night when I am off watch :-(
Captain Bligh was a NICE guy compared to me!
Having setup an ATC radar in Palm Springs, I can attest that the wind farms add a lot of noise to ATC radar systems as well as weather systems. Noise on the radar screen makes ATC more difficult, and increases the risk of accidents. The wind mills in Palm Springs are the small blade, fast moving type which birds like to fly into. I think the newer, larger wind farms are less of an issue for ATC radar. The slower moving blades can be filtered out. If they could build the windmills with flat edges, or use radar absorbing materials, they would become invisible to the radar.
.....after the number of Earth's wind mills reaches a certain critical population, the planet will fly away, leaving all air traffic in its wake.
Hebrews 11:8
Jeremiah 33:3
For many years I lived on a sailboat with a wind generator which shorted the output to stop the blades as well as to KEEP them stopped.
Worked fine even in gale force +++ winds.
It worked fine because the turbine was small and the genny was powerful. It was able to produce enough drag torque to pull the rotor down to stall speeds even in a gale.
Unfortunately, for big homebrew turbines the alternators can't be counted on to be sufficiently strong to accomplish this. (For starters ie means dumping the energy of the turbine's inertia, plus all the power the blades are pulling from the air before they get down to stalling speed, into the alternator coils as heat. On a big machine this may melt them.) Also: If the turbine is in stall and the wind gets high enough to overpower the genny if the turbine weren't in stall, a gust may start it spinning and pull it out of stall (or, as in your case, cause enough damage to the alternator to cause it to stop braking the blades effectively).
One VERY dark night headed for Fiji though a magnet came loose in the generator and THAT was spectacular! ... I now understand that the bade was close to MACH 1 when it broke free!
An important design parameter for wind turbines is TSR - Tip Speed Ratio. This is the ratio of the speed of the tip of the blade to the speed of the wind when the turbine is under load and achieving peak efficiency. (When unloaded, for instance if the battery came unhooked, the turbine will freewheel at something like twice that speed.)
Horizontal axis wind turbines (the wind-facing "propellor" type) are most efficient when designed for a TSR in the vicinity of 6. (Slower and they waste more power "spinning the exhaust". Faster and they waste more power in drag - and the airflow over part of the blade may go supersonic in a storm, which is not good.)
Speed of sound at 68F is about 768 MPH. That means a TSR 6 turbine will have the tips hit sonic speed at a wind speed of about 128 MPH under load or roughly 64 MPH freewheeling. (And that cube law means your genny will probably burn out in sustained winds approaching 128 MPH so you'll probably be unloaded at speeds well below 128.)
Of course holding the blade to the hub when the tip is moving near the speed of sound (or fast enough that part of the airflow is supersonic and making the blade vibrate horribly) takes a LOT of strength - usually more than the parts have. This is why wind machines are designed to furl somehow before they get spinning that fast.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
Wind turbines have a safe operation range, outside of that the windmill's brakes are engaged to prevent it from being damaged or destroyed (there's a youtube video of a wind turbine with a broken brake spinning up and shattering in a storm, extremely dangerous since you get large high-velocity fragments flying around that could probably demolish a house). I think the upper limit is something like 50km/h wind speed, above that the mills shut down.
Justice is the sheep getting arrested while an impartial judge declares the vote void.