Small windpower a scam ? Survey says SO

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  • BB.BB. Super Moderators, Administrators Posts: 32,019 admin
    Re: DWH - Windtronics

    Consumer Reports has a review on the Windtronics:
    ...The company claims the unit starts spinning from winds of a mere 0.5 mph—with electricity generated from only 3 mph. Traditional gearbox wind turbines, said the company, require at least 7.5-mph winds to start generating power.
    A tool on Windtronics' website had calculated we'd get 1,155 kWh per year at the 12-mph average it predicted for our area of Yonkers, New York. And the authorized installer, during his initial visit, didn't say the roof of our headquarters might generate any less, but that rating is at a height of 164 feet, not the 33 feet WindTronics requires for rooftop installations.
    In the 15 months since the turbine was installed, though, it has delivered less than 4 kWh—enough only to power a 12,000 btu window air conditioner for one afternoon. A company representative in charge of installations worldwide recently visited our offices and confirmed that our test model was correctly installed. What's more, he told us that while the WT6500 should start generating power at about 3 mph, the initial juice goes just to power the system's inverter, which must be running before it supplies any AC power elsewhere. The true wind speed needed to start producing AC while the inverter is on is 6 mph, not far from the 7.5 mph needed by a traditional gearbox wind turbine.
    ...
    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • TricksailingTricksailing Registered Users Posts: 22 ✭✭
    edited April 2019 #63

    I have had an Air-X Marine wind generator in Baja California for over 12 years and came to the conclusion that it's best function was to warn when winds start to pick up. I was surprised when I mentioned this to other sailors who laughed and said they had come to the same conclusion. Definitely not a reliable source of power in Baja - which has fairly low winds other than the occasional storm or hurricane. As someone in the thread noted, I concluded I could have got better value by spending my money on solar panels. The figures are there for people to digest, but not in an obvious form. It's easy to be wowed by impressive "30 KWh/month" claims while not connecting that is probably less than one tenth of the power needs of an average household. And that drops significantly when "real" winds are used. In Baja, a single $200 solar panel generates more power than the Air-X.

    If you go by the Air-X power output vs windspeed chart and convert from monthly KWh to amps or the windspeed vs output chart and convert watts to amps you get just over 1 amp in a 10 mph wind, 5 amps in a 15 mph wind. Max output at about 30 mph is about 37 amps. In Baja just one modest solar panel put out more than 5 amps.

    HOWEVER: The wind generator usually provided more than enough power on many cloudy/stormy days and in that sense was a good backup for when solar wasn't producing much.

    My Air-X is still running after 12 years, although it 'failed' due to corrosion between the aluminum hub and the blade roots. The expanding corrosion products literally pushed the blades off the bolts holding them to hub. The fix was an easy replacement blade kit but it could have been prevented by better maintenance.

    A couple of responses to some thread comments -

    "* A windmill receiving an average wind speed of 4.5 meters per second produces 7 times more energy than a windmill receiving an average wind speed of 3 meters per second."

    That sounds wrong to me. The same thread correctly notes a cubic power relationship between windspeed and power output. That would put the power output at 4.5 m/s at just under 3.5 fold - half of the suggested change.

    "add to that the air x will upon hitting 28mph will shut itself down from production for about 5 minutes meaning that the 20mph winds if producing gusts will render the thing useless for production"

    According to their specs, my Air-X is rated to 22 m/s (49 m/h). I recall mine operated well in 50mph winds without shutting down, although it would cut out in larger gusts but didn't take 5 minutes to restart. Perhaps the 28 mph shutdown is a fault in the device and requires some adjustment. Air-x have an output chart up to 60 mph here which shows outputs are limited at around 25-28 mph but still with outputs of 100 or 200 watts (8 or 17 watts) depending on the model.

  • VinerViner Registered Users Posts: 2
    edited May 15 #64
    On the Internet there are many interesting inexpensive offers of vertical wind generators with built-in charge controller from Chinese manufacturers.
     For example: www banggood com/1400W-DC-12-or-24V-5-Blades-White-Home-Use-Small-Turbine-Aluminum-Alloy-Die-casting-Vertical-Wind-Generator-with-Charge-Controller-p-1694030.html
    Has anyone tested these modern inexpensive solutions? Can you recommend that I use these Chinese wind generators for a household in Milwaukee, or for a farm in Wisconsin? It is written that the vertical wind generators rotate and run for a long time , in any even the weakest wind and give good power at the output of the generator.
  • BB.BB. Super Moderators, Administrators Posts: 32,019 admin
    This article on small wind turbines is still up:

    http://theoildrum.com/node/6954

    The first question is how much energy per day/month/year do you need?

    In general, a small system like this--Even if it works perfectly--You are looking at probably on the order of an average of 10 Watts over a 1 year period... And few VAWT seem to last very long.
    • 10 Watts * 24 hours per day * 30 days per month = 7,200 Watt*Hours per month = 7.2 kWH per month
    The average North American home uses something like 500-1,000 kWH per month.. Or 100x of these turbines to supply 720 kWH per month--Not a practical setup.

    Of course, the 10 Watt average is a pure guess on my part... There are not specifications for this turbine (power vs wind speed). And nothing much in the way of listing the physical size of the unit (other than "Wind wheel diameter 0.65m / 0.85m" from the Turkish youtube video).

    Remember that the energy harvested from wind goes with the Cube of the wind speed. Using:

    Starting Wind Speed ​​1.9m / s Maximum harvest(?) Wind Speed ​​12.1m / s
    Ratio in wind energy = 12.1^3 / 1.9^3 = 258x more energy at low/starting wind speed vs maximum harvest wind speed.

    Most wind turbines really begin to harvest power at 10-12 MPH (i.e., >zero Watts)....

    I don't believe this unit will harvest more than a tiny amount of energy--But I am not the expert--Just from what I have read over the years.

    If you want to spend $400 on the unit and wait for boat shipment from China--It is your time and money. Perhaps this one will be different.

    I am not a fan of small wind--So I probably am on the pessimistic side of the evaluation here.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,033 ✭✭✭✭✭
    The saying that the difference between an optimist and a pessimist has always been the pessimist has more data.

    Wind power generation (in meaningful amounts of power that can take a big puffs of wind over time)  has always been an advanced skill and requires the best design/implementation.

    Most people do not live in the right place to even waste their time and money on wind. If one really wants to persue this, they had better be willing to spend many thousands of dollars. I do have acess to pros who do this for a living, so drop me an email. 
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • VinerViner Registered Users Posts: 2
    edited May 15 #67
    On the Internet there are many interesting inexpensive offers of vertical wind generators with built-in charge controller from Chinese manufacturers.
    Has anyone tested these modern inexpensive solutions? Can you recommend that I use these Chinese wind generators for a household in Milwaukee, or for a farm in Wisconsin? It is written that the vertical wind generators rotate and run for a long time , in any even the weakest wind and give good power at the output of the generator.
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,033 ✭✭✭✭✭
    I think if you look at the history of these inexpensive solutions, you will find they have been there for decades.  I have never seen anyone come back and say they worked for more than a year or two. Most are for marine apps and they are priced to last about a year and then fail. The ones that do last probably have not been hit with high winds. The other failure mode is they overcharge the battery and can cause a fire. The power has to go somewhere ! They are not like a solar panel that can throttle back. They need to dump the load somewhere!

    Why don't you buy one and report back after a year or so? 

    I had one on my sailboat and serviced them for others. PITA compared to solar! 
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

  • BB.BB. Super Moderators, Administrators Posts: 32,019 admin
    Not sure about poster... He is probably out of the Ukraine and connected to selling these turbines. Nothing to do with Wisconsin--I guess.

    See if this is a conversation or not.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • Dave AngeliniDave Angelini Solar Expert Posts: 6,033 ✭✭✭✭✭
    Thanks Boss ! No sense in wasting time !   I will PM you in the next day or so. Pretty busy here now making electrons flow and trying to keep the town from burning this summer.   If it goes,  we go to Nevada or possibley Texas.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

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