A few thoughts on the "climate change lowers wind speeds" study

anemometer_in_the_breezeBy now you’ve probably read about Wind speed trends over the contiguous USA by Pryor et al. (2009, in press, JGR)

There is also an Associated Press story which cites this as a “first-of-its-kind study, and  suggests that average and peak wind speeds have been noticeably slowing since 1973, especially in the Midwest and the East.”

Steve McIntyre of Climate Audit  takes the study to task, not only for its data and conclusions, but for the Shenanigans of Michael Mann and Gavin Schmidt when they try to backtrack post facto after giving independent interview to AP’s Seth Borenstein and suddenly finding themselves in disagreement over whether “climate change” is involved or not. Go team.

I’ll point out that measuring wind accurately over a long period is not easy, particularly because surface anemometers tend to be problematic by the nature of their mechanical design. Aerovanes are better, but still have some of the same issues.

There’s also issues with land use change around the sensor long term, which I’ll get to in a moment. But first, the instrumentation.

For the traditional anemometer, here are some issues I’ve identified:

  • Cup anemometer accuracy is typically +/- 5% when new some are even less. It depends on cup size and how linear the detector is. Some are very non-linear at low speeds.
  • Anemometers, being mechanical, age, just like automobile engines, they are only good for so many revs of the engine before stuff wears down, affecting accuracy.
  • The most common aging problem of anemometers is dust/dirt accumulation in the bearings, which tends to slow them down. I used to have a collection of dead anemometers from the former California State Climatologist…the vast majority had sticky bearings. I’d use them as a prop then give them away to classrooms when I went out to give talks to kids.
  • Aging tends to affect low wind speeds more, by virtue of friction and by the fact that the lions share of wind measurements are at low speeds below 10mph. 40+ mph winds are not an everyday occurrence in many parts of the world. Easy to see in in plot of wind speed distribution. Of course there are exceptions.

    ND_New_England_Overview

    USHCN Climate Station, New England, North Dakota. Photo by Eric Gamberg

So, depending on how good the instrumentation is to start with, and how well it is maintained, we might see the slowdown in wind caused partly by long term sensor issues.

If maintenance of NWS/NOAA wind equipment used in this study is anything like what we’ve seen for the USHCN network, I think the answer will be self evident.

But there’s another issue- urbanization and the associated land use change.

On the Climate Audit thread, one of the commenters pointed out the wind record from the Great Blue Hill Observatory near Boston.

For those who don’t know, according to commenter MarkB “the Great Blue Hill observatory web site. GBH, is just south of Boston, USA, and supposedly has the longest continuous meteorology record in the country (1885-present). The observatory is at the top of the hill – 635 ft. – with a large woodland park all around. Wind speed is certainly down since 1980.”

Our own Evan Jones recently visited the Blue Hill Observatory for a TV interview on the surfacestations.org project by Mish Michaels at WBZ-TV in Boston. He pronounced it a CRN 3 by the way.

Here is a look at the observatory USHCN station. Click for large images direct from the Blue Hill website

The wind instruments are mounted on the old observatory tower:

See the graph of wind speed from the observatory below:

GBH wind data

Click for a larger image

The graph brings some issues about urbanization to mind. The Boston area has been highly urbanized.

Urbanization could be roughing up the boundary layer.

Clearings, buildings, shopping malls, subdivisions, etc. create more friction and turbulence in lower level winds than say, open fields or vast swaths of forest top. More turbulence tends to inhibit smooth flow of wind, this decreasing the wind speed.

Granted Blue Hill is a bit higher than surrounding surface, but I think the the effect of increased turbulence and drag in the highly built up northeast will make an impact even at higher levels.

see this report by Zhang et al on urbanization impacts in China:

http://www.lapc.ac.cn/UpLoadFiles/File/2008meeting/dahui/zhangning.pdf

Urbanization leads to “heat island”, “dry island” and wind speed loss over urban area …

See the wind speed plots comparing urban/non urban on page 11

The wind speed slowdown due to urbanization has been known for quite some time. Here’s an older book on the subject:

http://books.google.com/books?id=Dmky95hwKr0C&pg=PA1267&lpg=PA1267&dq=urbanization+and+wind+speed&source=bl&ots=LROm0yH9QH&sig=AfBcT6Velb71bOu7NPE8J3GGCU8&hl=en&ei=mJs2SrX0Jo3sswOT7a3SBQ&sa=X&oi=book_result&ct=result&resnum=5

page 1267:

Yet, the surface roughness of the city serves to reduce wind speeds…

and others:

http://ieeexplore.ieee.org/iel5/4534879/4534880/04535390.pdf?arnumber=4535390

Due to the friction and drag of buildings, there are wind speed losses over urban area in all cases (Fig.4). In summer, the reduce of wind speed can be 1.0 …

It seems then, since Blue Hill Observatory is in the middle of a large area of growth for the past 50 years, that some of this wind speed reduction related to land use change and urbanization would apply?

Have a look at this Google Earth 3D image showing the patchwork quilt of the terrain around the observatory. Note the may holes in the forest canopy around the observatory and the signs of ubanization. How much of that affects wind speed measured on the hill? How much of it was there 30, 40, 50 years ago?

Click for a larger image

The Great Blue Hill Observatory and surrounding terrain - click for a larger image

I’d also like to find out when they last replaced/recalibrated their wind sensors. It is one of the sensors where detecting a problem is not always obvious, especially when they clog up with dust in the bearings.

When studies cite surface data from weather stations, it is always a good idea to look at land use/land change around the stations as well as the station instrumentation. Chances are you’ll find issues that may not have been considered.

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62 thoughts on “A few thoughts on the "climate change lowers wind speeds" study

  1. The ‘study’ is of course, just plain poorly done. (Hey, was it peer reviewed?
    To make things worse, the authors made statements to the popular press that are not backed up by the actual content of the study. The press of course, just ran with the story without trying to verify anything. Why? Because it reinforced global warming fears.

  2. Related: High-Altitude Wind Machines Could Power New York City
    http://www.wired.com/wiredscience/2009/06/highaltitudewindpower/
    Wired Science News for Your Neurons
    High-Altitude Wind Machines Could Power New York City
    * By Alexis Madrigal Email Author
    * June 15, 2009 |
    * 6:36 pm |
    * Categories: Earth Science, Energy, Environment
    The wind blowing through the streets of Manhattan couldn’t power the city, but wind machines placed thousands of feet above the city theoretically could.
    The first rigorous, worldwide study of high-altitude wind power estimates that there is enough wind energy at altitudes of about 1,600 to 40,000 feet to meet global electricity demand a hundred times over.
    The very best ground-based wind sites have a wind-power density of less than 1 kilowatt per square meter of area swept. Up near the jet stream above New York, the wind power density can reach 16 kilowatts per square meter. The air up there is a vast potential reservoir of energy, if its intermittency can be overcome.
    Even better, the best high-altitude wind-power resources match up with highly populated areas including North America’s Eastern Seaboard and China’s coastline.
    “The resource is really, really phenomenal,” said Christine Archer of Cal State University-Chico, who co-authored a paper on the work published in the open-access journal Energies.”There is a lot of energy up there, but it’s not as steady as we thought. It’s not going to be the silver bullet that will solve all of our energy problems, but it will have a role.”
    For centuries, we’ve been using high-density fossil fuels, but peaking oil supplies and climate concerns have given new life to green technologies. Unfortunately, renewable energy is generally diffuse, meaning you need to cover a lot of area to get the energy you want. So engineers look for renewable resources that are as dense as possible. On that score, high-altitude wind looks very promising.
    Wind’s power — energy which can be used to do work like spinning magnets to generate electricity — varies with the cube of its speed. So, a small increase in wind speed can lead to a big increase in the amount of mechanical energy you can harvest. High-altitude wind blows fast, is spread nicely across the globe, and is easier to predict than terrestrial wind.
    These properties have led inventors and scientists to cast their hopes upward, where strong winds have long been known to blow, as Etzler’s dreamy quote shows. During the energy shocks of the 1970s, when new energy ideas of all kinds were bursting forth, engineers and schemers patented several designs for harnessing wind thousands of feet in the air.
    The two main design frameworks they came up with are still with us today. The first is essentially a power plant in the sky, generating electricity aloft and sending it down to Earth via a conductive tether. The second is more like a kite, transmitting mechanical energy to the ground, where generators turn it into electricity. Theoretically, both approaches could work, but nothing approaching a rigorous evaluation of the technologies has been conducted.
    The Department of Energy had a very small high-altitude wind program, which produced some of the first good data about the qualities of the wind up there, but it got axed as energy prices dropped in the 1980s and Reagan-era DOE officials directed funds elsewhere.
    The program hasn’t been restarted, despite growing attention to renewables, but that’s not because it’s considered a bad idea. Rather, it is seen as just a little too far out on the horizon.
    “We’re very much aimed these days at things that we can fairly quickly commercialize, like in the next 10 years or so,” said National Renewable Energy Laboratory spokesperson George Douglas.
    Startups like KiteGen, Sky Windpower, Magenn, and Makani (Google’s secretive fundee) have come into the space over the last several years, and they seem to be working on much shorter timelines.
    “We are not that far from working prototypes,” Archer said, though she noted that the companies are all incredibly secretive about the data from their testing.
    Magenn CFO Barry Monette said he expects “first revenue” next year when they sell “two to four” working prototypes of their blimpy machine, which will operate at much lower altitudes.
    “We do think that we’re going to be first [to market], unless something happens,” Monette said.
    In the long term, trying to power entire cities with machines like this would be difficult, largely because even in the best locations, the wind will fail at least 5 percent of the time.
    “This means that you either need backup power, massive amounts of energy storage, or a continental- or even global-scale electricity grid to assure power availability,” said co-author Ken Caldeira, an ecologist at Stanford University. “So, while high-altitude wind may ultimately prove to be a major energy source, it requires substantial infrastructure.”
    —————-
    Personally, I think unmanned blimps tethered to the surface may be a better idea than kites because blimps will remain aloft when the wind isn’t blowing, whereas kits would fall back to earth.

  3. So how much did the experts talk about these issues in their paper?
    P.S. The dissection of the paper at CA was by ryanm.

  4. I’m pleased to see that Blue Hill graph make it “above the fold”, I’ve posted the link here a few times.
    The hike up to the top of Blue Hill makes it clear that the terrain dominates the architecture. Events like building the ski trails (I have no idea when that happened) would show up as steps in the graph if they had any effect. The area around the observatory has a lot of bare rock, so I doubt tree growth has had an impact.
    I don’t know what’s behind that trace since 1980. The PDO flipped negative the year before, but the previous cycle doesn’t show up. I doubt it’s connected to the Livingston and Penn solar observations. (Just kidding!)
    I do have some additional anecdotal information. The Eastern Massachusetts coast has had severe storm flooding, e.g. the hurricane force winds with the Blizzard of 1978 brought widespread destruction. In the years after that a friend of my sister who lived on the coast (I think she moved there in the 1980s) began evacuating whenever a strong nor’easter was predicted. (Early to mid 1990s now.) Something about begin flooded soon after replacing the stuff destroyed by the previous flood and also having a small son to look after does that to people! Eventually, the family managed to sell the house and mostly solved the problem. They still worried about being sued by the new owners after the next flood, however the new owners never got flooded and they eventually sold the house to others and my sister’s friend is finally at ease.
    Clearly there’s empirical data to bolster this, I’m sorry I don’t have any handy, perhaps the Blue Hill folks do.
    Bottom line – don’t be too quick to discount that graph. At least, I don’t know how to discount it!
    BTW, I thought rising sea levels were supposed to bring more coastal flooding. Massachusetts may have missed that memo. Cape Cod is still washing into the sea, but it’s a relic of the Ice Age and should be washing into the sea.

  5. You guys are rather smart. I started yacht racing on an inland lake which was built 43 years ago. It was barren and now we have trees over 50′ in height. Many club members are pilots and aeronautical engineers. many of us have used digital display instruments for 25 years.
    In racing we still use tiny little ribbons on sails for detecting airflow. It is not uncommon to “catch some air” up 30-40 feet that is not on the waters surface. We all read wind and read wind shifts. With thermals and lift, it is still easy to sail a few miles and know where to catch a breeze others can’t see.
    Dark plowed fields create heat and lift the airflow. Just like measuring ocean temps at many levels, it is best to measure windspeed and directions at many levels. sorry that surface data is far from enough. In the case of racing, it can be wind speed measurements can changed by a disruption a mile away.

  6. Look the science is settled….settled I say, how dare you disagree with the experts who say its to do with GW and not to do with global warming……oh…erm….well its causing the extinction of Polar Bears and they are cute!

  7. So Climate Change causes lower wind speeds and more hurricanes.
    And the heartbreak of psoriasis, no doubt.

  8. Weather is an integral part of Climate.
    Just as sunspots are an integral part of the Solar Cycle.
    If Weather never changes, neither will Climate, but it does.
    If sunspots never changed, there would be no Solar Cycle, but they do.

  9. With all the terrain variables and the natural instrumentation degradation over time, it seems discerning long term wind speed trends may be even more difficult than discerning long term temperature trends.

  10. Now that I’ve looked at the photo’s on the Great Blue Hill Observatory site I have a question. I saw downtown Boston in the near distance.
    So, what is the predominate wind direction at this site? Any data for wind speed over time in the Boston metro area?

  11. [Anthony]If maintenance of NWS/NOAA wind equipment used in this study is anything like what we’ve seen for the USHCN network, I think the answer will be self evident.
    I have a few comments about this too. If Blue Hill’s anemometer were slowing down due to age, then that’s a concern. However, there’s a flaw in that argument. While they do have a large propane grill, we’re not talking about a North Dakota backyard. We’re talking about an observatory with staff, outreach, meteorologists, etc. They don’t have one anemometer, they have several, see http://www.bluehill.org/instruments/instruments.html for some of them. One questionable piece of gear is their own ASOS station. It’s observed but not maintained by the staff. It’s a test system to provide baseline information to see how well other ASOS stations fare over time versus a manned station. (Indeed, there have been periods where BHO reports included comments about the ASOS anemometer being frozen or rainfall gauge being wrong for days before someone came out to fix it.
    (For those unfamiliar with ASOS – it’s an automated station that has replaced most of the manned airport stations and provides current weather conditions and cloud information up to 12,000 feet. Many people don’t trust or like them. Not surprisingly, this includes some of the people displaced. I don’t know enough about them to be very judgmental except that I find the observer comments are often the most interesting and useful part of a weather OBS.)
    So, sure, one aging anemometer could lead to an erroneous 30 year record, but the photo at that link shows five anemometers (plus the ASOS). Surely any “sticktion” would be noticed immediately, and gummy bearings eventually.
    BTW, the “crystal ball” instrument is an antique sun vs. cloud recorder. It’s mounted in contact with a paper strip and the index or refraction focuses sunlight on the paper surface. During the course of the day sunny times are recorded by the burn mark left on the paper. They use different shapes for the paper as a function of the season, e.g. a rectangular shape is ideal at the equinoxes. A new piece of paper is installed every day when precip isn’t in the forecast.
    I don’t know if they’ve put the data into computer form, it would be nice to see what their record is for cloud cover over time.
    REPLY: This post evolved over two days from two sets of comments, first on Lucia’s and then on CA. I wasn’t pointing at Blue Hill initially, but more at anemometer issues in general. Most stations have a single anemometer. Still it would be interesting to see if they do in fact have a maintenance schedule and calibration schedule for the anemometers at Blue Hill. – Anthony

  12. Stephen Singer (10:02:15) :

    Now that I’ve looked at the photos on the Great Blue Hill Observatory site I have a question. I saw downtown Boston in the near distance.
    So, what is the predominate wind direction at this site? Any data for wind speed over time in the Boston metro area?

    Boston is about 10 miles and a little east of due north. Winds are typically NW in the winter, SW in the summer, east when backdoor coldfronts or other purveoyors of maritime air hang around.
    Coastal storms have NE winds (nor’easters that pass just off the coast) or SE (coastal storms that take an inland track – in the winter these are generally all rain events at Blue Hill but often bring big snowfalls to western Mass and new Hampshire).
    Due north or due south winds are fairly rare.
    Other sources for wind information include Logan airport in Boston, Worcester airport to the west and at 1000 feet. The NWS office is in Taunton, not too far from the Blue Hill reservation. I haven’t looked into any of it, but the NCDC dutifully records it all.

  13. Well, their wind speed study is all fine and dandy, but from living on the Great Plains of North Dakota for a very long time, I can tell you unequivocally, there is no way you can convince me that wind speed has declined over the years. No way, no how. I find the conclusions to this study to be one of the more absurd things I have ever heard. In my book, this study is absolute bovine craptology.

  14. Global warming causes more snow/less snow, more rain/less rain, more drought/less drought, more wind/less wind, and, in fact, no matter what the weather does, it’s because of global warming. Heck, it even causes global warming advocates to make contradictory statements to the press as was done by Mann & Schmidt. So there you have it – global warming causes confusion.

  15. I find Michael Mann position on this study very interesting. It shows that he lacks the skepticism required by any good scientist and that he is ready to believe anything as long as it supports his belief.

  16. Well, it should be obvious to everyone, wind causes global warming! Not the other way around.
    We must build massive wind breaks and stop this deadly phenomenon! We must all stop driving and flying around so as not to disturb the air and produce unnecessary wind that could cause temperatures to rise and ice caps to melt! Hurry, before time runs out, we must all stop where we stand, don’t move!
    Sorry, I just can no longer take it, the absolute sewage sludge that some people (disguised as scientists) keep trying desperately to pass off as science. Science has eroded so severely. It is a shame, a crying shame.
    Keep up the great work here Anthony! It’s blogs like this that may become our last hope!

  17. Low velocity wind speed is notoriously difficult to measure accurately, due in part to invisible eddy currents and changes in air pressure. No doubt land use changes upwind have a similar effect.

  18. Squidly (10:36:55) :

    Well, their wind speed study is all fine and dandy, but from living on the Great Plains of North Dakota for a very long time, I can tell you unequivocally, there is no way you can convince me that wind speed has declined over the years.

    I should apologize a bit to Anthony for getting so excited about the Blue Hill wind speed plot, however, it is my favorite meteorological “secret” and deserves nationwide (maybe worldwide) attention. I don’t know of good papers on it, but have offered space to Blue Hill, I’m sure Anthony would make room.
    I look at the BHO plot as a coastal effect that reflects a decline in coastal storm strength over the years. I don’t think nor’easter frequency has changed. As such, it may not be applicable to the wider region covered by Pryor et al.
    OTOH, despite claims that AGW will lead to stronger storms, other claims such as the poles undergoing disproportionate warming, suggests that the reduced temperature gradient would lead to weaker storms and weaker overall winds.
    One thing that might help identify failing anemometers is to look at how long periods of nighttime calm are. With the loss of daytime heating and growth of the nighttime inversion winds tend to slow down gradually. In the morning they pick when the inversion erodes and heating allows ground level and high level air parcels to mix, bringing high level winds down to the ground by the end of the morning.
    With all the focus being on the temperature record and that beginning to wind down, wind speed is a good next project.

  19. Late 2008, the Royal Meteorological Observatory of Belgium published the results of its study on the climate evolution in Belgium. “Eye on the Climate” covers the period 1833-2007 and covers the evolution of the various climate parameters and the possible factors that can influence the climate in Belgium.
    It can be found at http://www.meteo.be/meteo/view/fr/66965-Derniers+communiques.html?view=2791768 (Vigilance climatique), but unfortunately, there exists no English version. A quick summary of the most important conclusions can be found on my website http://users.telenet.be/j.janssens/Engwelcome.html (Climate – 19 Jan 09)
    Figure 17 clearly show the same decrease in windspeed (Uccle) as is shown in figures on this thread, and this evolution can also be found in the data of other weatherstations in Belgium. Some of these stations are not near a city, or the surrounding vegetation has not changed appreciably over the last half century or so.
    The text also mentions that this downward trend did not show up in the winter season, which happens to be the season during which windspeeds are usually the highest.

  20. Maybe OT but I have wondered how much the wind turbines that are presently installed are affecting the wind pressures and how the area behind the turbines is no longer straight but has a swirl effect. It is also possible that the turbines are taking strength out of the wind by transforming the energy from wind to electrical.
    PhilK

  21. Well one thing I am sure about the weather in the bay area; which is a short clip of what will be integrated into our climate record, and that is that our climate; and by inference our weather, does not originate at the Golden Gate Bridge; which they are going to rename the Lead Gate Bridge, as the gold has left this state.
    That whole darn hill on which that ancient weather station resides could have had not a single stick of construction anywhere on it since the station was built, and not a human set foot on the hill since, and I bet the winds over the hill would have changed as a result of the urban changes miles away.
    I believe the graphed data is quite real; and I also believe that the climate information in that long history of wind data is 0.00 +/- 15
    I’m sure you could gather the same information from any remote hill on earth and it would also reveal some pattern of wind history change; and once again containing zero information (other than the wind has changed at that place).
    Now unlike the Aussie Antarctic listening post; this wind record, is a perfect example of meaningless data gathering. Well perhaps I shouldn’t be too harsh. The raw record contains information on what wind speeds were observed at what time on what day. Nice for reporting a historical min/max number in the Boston Globe; by climatologically meaningless.
    I should add that I suspect that other data gathered at this site on other weather vartiables is quite valuable.
    It is hard to imagine any weather variable that we can easily measure, but perhaps not too long term reliably as Anthony describes that is more totally chaotic than the air flow through a fixed volume of space comprising maybe one cubic foot of volume out of the entire atmosphere. Is some climate statistician going to try and convince us that the record of that anemometer is valid for distances up to 1200 km away, as they claim for temperature anomalies. You movew that sensor up or down a few feet or shift it 100 feet on that hill and you’ll get a totally different record.
    Talk about cherry picking; so who selected that particular cubic foot of atmospheric volume to monitor.
    Yes the long term record is very interesting to see; but its information input to the global climate puzzle is worthless.

  22. John Galt (08:54:58) :
    High-Altitude Wind Machines Could Power New York City . . .
    . . .Personally, I think unmanned blimps tethered to the surface may be a better idea than kites because blimps will remain aloft when the wind isn’t blowing, whereas kits would fall back to earth.

    That’s all we need, a whole bunch of wires running up to altitude for little and big airplanes to run into. But how could we argue against something that would reduce the need for carbon generating base load power plants to counter the unreliability of wind turbines and other renewable, sustainable, organic, and pristine sources. Maybe enough of them around New York could prevent the next 9-11.
    .
    I tried plotting an inverted CO2 (chemical) graph over the wind speed chart. Matches about as well as it does with temperature, i.e., don’t bother.

  23. The Blue Hill picture dialogue for the microbarograph is in error stating that the chart is changed daily. If memory serves, the charts are good for five – seven days.

  24. PhilK (11:26:32) :
    Not a bad assumption. Nature is feeding only so much wind to a given place. Just like it wants to feed so much precipitation to any given area. Attempts at “precip enhancement” have often proven your assumption. So do idle wind generating farms.
    Where it really got scary is the attempt at seeding out the Atlantic Hurricanes.
    Maybe someone should dig up the why and what of the Hurricane Seeding that was called off.

  25. Interesting this is considered a place for good history of weather conditions. The Blue Hills ski area is built right below the Observatory. See here picture here: http://www.skireport.com/massachusetts/bluehills/trailmap/?id=272
    It was built in 1940’s. It has had many changes in number of trails (cutting of trees), buildings, etc. It also went into disrepair sometime in the last 10 years and was just reopened. More interestingly it was the first ski resort to use artificial snow making (I doubt that would affect temp, humidity, etc.) in late 1950’s.

  26. Windmills, the most poetic and futile creation of global warming imagination,
    Windmills, the most pathetic and gruesome product of “climate change”,
    Windmills, windmills, windmills to dry up winds, to ruin poetry, to cut sun into pieces, its light in shadows iterative ,
    to kill birds, to break hearts with dissonance, to hasten old men’s departure
    from an alien land they didn’t know when young,
    to tear down the will, to chop soul in mindless and colorless patches,
    Windmills, phantoms on deserted lands,
    Windmills which ended love, which ended life.

  27. As one who has competed in target shooting, outdoors, for nearly 25 years, I can tell you that the wind has not diminished in the midwest or Rocky Mountain region. It does change greatly from day to day, season to season. But less of it? Hardly.
    I also have a hard time believing wind power varies as the cube of the speed. We are talking about a transfer of momentum, moving air mass to moving windmill blade. The efficiency of the turbine might increase with speed, especially at low speed, but the cube? You got some serious conservation of momentum and energy problems here. Drag increases at about the square of the velocity, but that’s a different animal.
    Getting power down from 20,000 feet will require a very interesting conductor (pair). Not too many wires can support that length. So we wrap it in Kevlar and hope it doesn’t break? Gonna take a mighty big kite or balloon to support it. Hard to pass the laugh test.

  28. John Galt (08:54:58) :High-Altitude Wind Machines Could Power New York City . . .. . .Personally, I think unmanned blimps tethered to the surface may be a better idea than kites because blimps will remain aloft when the wind isn’t blowing, whereas kits would fall back to earth.
    Mike McMillan (11:52:53) :
    That’s all we need, a whole bunch of wires running up to altitude for little and big airplanes to run into.

    Probably safer than your roof mounted construction cranes.

  29. “”” Retired Engineer (13:48:35) :
    As one who has competed in target shooting, outdoors, for nearly 25 years, I can tell you that the wind has not diminished in the midwest or Rocky Mountain region. It does change greatly from day to day, season to season. But less of it? Hardly.
    I also have a hard time believing wind power varies as the cube of the speed. We are talking about a transfer of momentum, moving air mass to moving windmill blade. The efficiency of the turbine might increase with speed, especially at low speed, but the cube? You got some serious conservation of momentum and energy problems here. Drag increases at about the square of the velocity, but that’s a different animal.
    Getting power down from 20,000 feet will require a very interesting conductor (pair). Not too many wires can support that length. So we wrap it in Kevlar and hope it doesn’t break? Gonna take a mighty big kite or balloon to support it. Hard to pass the laugh test. “””
    Maybe it’s time to take a refresher cours Retired.
    You say that drag increases at about the square of the speed; in the simplest of models, no need for the about. So the “lift” and the “drag” are about in a constant ratio over the efficient range of the airfoil (propellor), so one would expect the lift to also increase as the square of the speed. That is the force being applied to the rotor, and if it moves some fraction (1-s) of the wind speed, where (s) is the prop slip, then the product of force and distance travelled in a certain time is the power. In water, prop slips are of the order of 10%, but I don’t know what it is in air, in any case the speed of the prop is some reasonably constant fraction of the wind speed. so that brings the power to the cuube of wind speed, over the efficient range of wind speeds, and rotor air foli design.

  30. Retired Engineer (13:48:35) :

    I also have a hard time believing wind power varies as the cube of the speed. We are talking about a transfer of momentum, moving air mass to moving windmill blade. The efficiency of the turbine might increase with speed, especially at low speed, but the cube? You got some serious conservation of momentum and energy problems here. Drag increases at about the square of the velocity, but that’s a different animal.

    I think we’ve been through this before, but I think the answer is easy.
    Each air molecule has kinetic energy proportional to 1/2 mv^2. (Just call it v^2) The number of molecules interacting with the windmill is proportional to v. Total energy interacting with the windmill is proportional to v^2 x v, or v^3. QED.

  31. Anyone from Boston know what happened at Fenway when they built the sky boxes behind home plate? There was a significant drop off of home runs and a study showed that the sky boxes changed the wind patterns inside the ball park.
    UWI – urban wind island. Gotta account for it.

  32. Wind power increasing in a windmill as the cube of velocity is a consequence of simple high school physics–the kinetic energy of each unit mass of air is proportional to v-squared, and the rate at which mass hits the windmill is proportional to v. Thus, energy/time (power) is proportional to v-cubed if windmill efficiency is approximately constant with wind speed (which it is over small ranges).
    Over larger ranges, efficiency increases as speed increases at low-ish velocities, but then begins to decrease at a high-ish velocity which is dependent on the design of the windmill.

  33. I’ve always like the acoustic anemometers. By measuring differential air speed acoustically a few hundred times a second they can provide accurate three dimensional look at air flow. The devices are not subject to the inertia of anemometers.

  34. Carbon nanotube conductors are more conductive than copper and stronger than steel. Unfortunately they are unavailable currently in industrial quantities.

  35. Actually, IMHO, it makes sense that “climate change” would impact wind speed.
    Here’s my reasoning; the climate is essentially a heat engine, and wind speed is a function, in some cases, of temperature differentials between the equator and the poles. Therefor, it seems to me that if the energy input (from the sun, TSI, magnetic, etc,) was declining, it would reduce average windspeeds. (however, in that case, this effect would, i think, be most noticeable in the last few years rather than long term)
    Therefor, IMHO, it seems to me that a reduction in windspeed could better be explained by a cooling planet than a warming one.
    Incidentally, the cynic in me wonders; is the shift of the AGW’ers from “Global Warming” to ‘Climate Change” calculated, so that a cooling planet, or any other climate phenomenon, fits the “Climate Change” scenario?

  36. The Weather Channel is talking about this topic also in the “Climate & Green” section of their web site :
    “Still, the study, which will be published in August in the peer-reviewed Journal of Geophysical Research… it raises a new side effect of global warming that hasn’t been looked into before.” (bold italics me)
    http://climate.weather.com/articles/notsowindy061001.html

  37. Retired Engineer– (I’m one too.) Re-read your old Fluids text. The energy does increase with the cube of velocity.

  38. Should I joke about checking for an urban leeward effect by driving across a city and finding much higher windspeed than at weather stations, and slower windspeeds near the center?

  39. Looking at the pictures around the hill, there appears to be alot of new growth hardwood forest. Perhaps much of the decline since 1980 can be attributed to the Bernoulli effect. It would be interested to see if the trend is the same for both winter and summer.

  40. M. Simon (15:53:52) :
    Carbon nanotube conductors are more conductive than copper and stronger than steel. Unfortunately they are unavailable currently in industrial quantities

    Soon you will have nanocopper pigmented conductive plastics
    http://www.giurfa.com

  41. How about heated wire anemometers? I’ve been researching these as I plan on building one to be able to monitor wind speed in my yard. Worth doing or should I be looking for something more conventional?
    REPLY: They don’t hold up in weather very well. – Mostly lab use. – Anthony

  42. I read the AP article on this a couple days ago and was instantly struck by the passage in which Gavin Schmidt exressed skepticism of the results, but only on the basis that the computer models showed no reduction in wind speed. That’s like being skeptical of a report of a quarter inch of water in a rain gauge on the basis that the computer models didn’t forecast any rain. It says a lot when a climate scientist’s knee-jerk reaction is to accord more weight to a virtual simulation of a system than the actual measurements taken of that system.
    Granted, trying to confidently identify a real trend in a climate variable is difficult given the uncertainties in the instrumentation, not to mention the chaotic nature of the system itself; hence any study like this should be scrutinized carefully. But it makes little sense to me to have more confidence in a model of a system than you do the real-world measurements of that system. If the real-world measurements of climate are so fraught with uncertainty as to be dismissed that readily, then it stands to reason that the climate models built on those measurements have to be accorded even less certainty, not more.
    In other words, if we don’t have the ability to even measure changes in wind speed with any confidence in the real world, how is it that we’ve gained the knowledge with which to imbue in a computer the more-difficult ability to calculate the specific transient response of wind (no change) to a particular input (radiative forcing). It’s not as if the compuer models were handed down to us by some technologically-advanced aliens. The computer model is only as good as the programming that went into it, and the programming is only as good as the ability to measure the actual system.
    Now, in all fairness, the AP could have truncated his criticism or taken the comment out of context, but if it did accurately reflect his view of the study, then I really question this guy’s objectivity. What I think is happening is that many climate scientists are accepting the results of computer models as substitutes for real data, not because there is a reasoned basis for doing so, but because the results are clean and unambiguous whereas trying to determine the inner workings of the climate through the more rigorous scientific practice of taking measurements is messy and uncertain. When a computer model says “x” input produces “y” effect in 95% of the trial runs while holding other inputs constant, then the results are black and white. When measurements merely show “y” effect (e.g. a temperature trend) in an uncontrolled system then attributing causation to any particular variable is a very difficult thing. But just because a climate model is more convenient doees not mean that it’s accurate, and is surely isn’t a basis for questioning real data.

  43. I will grant you the theory says cube, but from limited experience with small remote power generation, I haven’t seen anywhere near 8x the output for a doubling in wind speed. So I suspect something else is at work. Theory and practice are not always the same.
    In John Gault’s post, the article he quotes says: “even in the best locations, the wind will fail at least 5 percent of the time.”
    Maybe at 20,000 feet. A bit more at the surface.

  44. “just because a climate model is more convenient doees not mean that it’s accurate”
    This is the root of the problem, the GCMs require tractable solutions to a huge problem involving chaotic elements. It would be fine, for advancing knowledge, but betting trillions on what are at best, preliminary findings, and at worse, complete fabrications is going way beyond what the “science” will support. We are at the state in climate science that Lamarck was at in genetics.

  45. “”” Retired Engineer (07:17:59) :
    I will grant you the theory says cube, but from limited experience with small remote power generation, I haven’t seen anywhere near 8x the output for a doubling in wind speed. So I suspect something else is at work. Theory and practice are not always the same. “””
    Well I have always understood the question to be one of “available” power, which most definitely goes as the cube of wind speed.
    That does not mean that a fixed design will actually yield 8 times the power for double the wind speed.
    For a start, existing wind turbines that I am familiar with are ALL fixed RPM designs; that being necessary to phase lock the alternators to the grid line frequency.
    That means that wind speed changes would have to be accommodated by rotor blade adjustment of angle of attack, to extract greater lift and torque from a fixed airfoil section. And I would be very surprised if high efficiency can be obtained over an 8x lead range at fixed RPM.
    In fact I believe that simply fixing the operating RPM takes away one of the doublings, so the available power is now only 4x for a doubled wind speed.
    It would seem that to realize the additional power you have to let the rotor free run, and use a torque converter to drive and phase synch the alternator; and I wouldn’t want to have to design that torque converter, and keep it running; not to mention the risks of having the rotor free to run at a variable rpm.
    George

  46. George E. Smith (10:39:39) :
    Hi George,
    From what I read, new turbine/generator designs in Europe don’t use fixed rotor speeds for phase lock. Instead they use an electronically rotated field in the generators. This allows them to vary the rotor speed and still phase lock. Basically an electronic torque converter.

  47. I work with this data for a living, and I can tell you that NOAA/NCDC data have serious problems, especially at low wind speeds. The conversion to ASOS practically eliminated reporting of wind speeds less than 3 knots (rounding these down to 0). Even higher wind speeds often report as variable direction (often rounded to zero wind speed), and “calm” conditions are exceedingly frequent at many sites where only light breezes commonly occur.
    Maintenance on the wind sensors, especially in low-wind areas and away from NWS offices and climate stations, is if anything even worse than that for temperature data, which frequently deviates noticeably from reality undetected for years on end. Unfortunately, wind speeds appear highly dependent on station siting and exposure. Moreover, high-wind events generally occur on localized spatial scales (and also frequently knock out power to the ASOS during extreme events, rendering the system entirely useless). The local nature of high-wind events inhibits detection of erroneous instruments, especially in areas generally unserved by other networks.
    Another factor that you didn’t mention: trees. The more numerous and taller they get, even some distance from the site, the more effectively they block and obstruct wind flow. I wouldn’t be surprised if tree growth alone accounted for a significant proportion of the apparent slowing of the wind at Blue Hill, Massachusetts–a site chosen apparently for its great exposure that trees now perhaps partially block. Trees unfortunately tend to increase in height gradually on their own, so detection, adjustment, and remediation aren’t easy.

  48. I mentioned above that some people are not fond of ASOS weather stations. If we are to believe the one on Martha’s Vinyard, an island off the coast of Massachusetts, then http://adds.aviationweather.gov/metars/index.php for KMVY includes this morning’s report:
    METAR text: KMVY 170808Z AUTO 00000KT 3/4SM R24/P6000FT -SN BR SCT001 SCT007 03/02 A3025 RMK AO2 P0000 TSNO
    Conditions at: KMVY (MARTHAS VINEYARD, MA, US) observed 0808 UTC 17 June 2009
    Temperature: 3.0°C (37°F)
    Dewpoint: 2.0°C (36°F) [RH = 93%]
    Pressure (altimeter): 30.25 inches Hg (1024.5 mb)
    Winds: calm
    Visibility: 0.75 miles (1.21 km)
    Ceiling: at least 12,000 feet AGL
    Clouds: scattered clouds at 100 feet AGL
    scattered clouds at 700 feet AGL
    Weather: -SN BR (light snow, mist)
    Snow! Well, maybe not. It’s certainly cold enough for snow, but there was no precip in the forecast. What most likely happened is that site is well known for extreme radiational cooling despite being surrounded by ocean. The snow was probably just fog, that’s something ASOS has a little trouble telling apart.
    Sometimes a pair of operational human eyeballs trumps a non-sleeping semi-blind heap of electronics.
    It is believable that KMVY did get into the 30s, other stations nearby including the NWS office in Taunton reported temperatures in the 30s. Blue Hill, well above the inversion, got down to 50F.
    See also my source
    http://www.jotsweather.com/JotsWeather/JotsArticles/Entries/2009/6/17_Snow_at_Martha%E2%80%99s_Vineyard_this_morning.html

  49. The power from the sky plans show up every few years. The first question to ask is
    always, how much does the tether weigh? I can imagine improvements in materials
    that will back it possible to put such a power plant in the sky. The next question to
    ask is how big a space must be cleared in case the tether breaks?

  50. “”” KLA (16:58:43) :
    George E. Smith (10:39:39) :
    Hi George,
    From what I read, new turbine/generator designs in Europe don’t use fixed rotor speeds for phase lock. Instead they use an electronically rotated field in the generators. This allows them to vary the rotor speed and still phase lock. Basically an electronic torque converter. “””
    Hey Thanks KLA, I guess that makes a lot of sense. Trying to phase lock a mechanical contraption that all kinds of rotational moment of inertia; given that it is being powered by a chaotic driving force; with gusts and holes and all kinds of sudden impulses; I can see why they shake themselves to death. They already have a sychrounous vibration mode due to the vertical wind shear so that all three blades are not producing the same thrust at any time so the blades tend to flutter with the lift variation each revolution.
    Do you happen to know if Hydroelectric Turbines use similar techniques. I took a look at those monster Siemens alternators at Grand Coulee up in Washington; and I though about some water shock wave being sent up the tunnel if the got some sort of load dump problem; that’s a lot of inertia to have intermittent loading on.
    At least with hydros, the dam and lake let them supply a very constant water drive; but how do you low pass filter the wind to a big fan blade.
    George

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