Vertical Axis

oglethorpoglethorp Solar Expert Posts: 29 ✭✭
I'm in an area mostly on a large hilly area with lots of wind. (Central Maine)
But with the tree lines and as the land rolls there's a bit of
turbulence unless I go up 50' or so. Just trying to get a kite
up on a windy day tales a bit of effort until it gets to that
50'+ range. So my question is could a VAWG do the trick dealing
with the changing wind direction and turbulence at about 20 to 30' off the ground.
And then with the hundreds of vertical wind generators out there
has anyone found a reliable solution?
Thank you all in advance!
Off grid Solar 48v

Comments

  • BB.BB. Super Moderators, Administrators Posts: 32,212 admin
    Re: Vertical Axis

    Turbulence is lost energy--There is nothing that can recover the energy once the air is turbulent.

    There are a few successful models of horizontal axis wind turbines (well designed, well built, installed correctly on 60-90+ foot tall towers away from tall obstructions).

    I am not sure I have seen one article/installation of a "successful" vertical axis wind turbine. They don't generate much power and tend to be even more difficult to build so they hang together for years to come.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • oglethorpoglethorp Solar Expert Posts: 29 ✭✭
    Re: Vertical Axis

    Just trying to find the best use of a bad location.
    Turbulence will always be an issue but hope to use 100%
    of the 60% available low to the ground without a high pole mount.
  • BB.BB. Super Moderators, Administrators Posts: 32,212 admin
    Re: Vertical Axis

    No, the losses near the ground in turbulent air will be close to 100% loss... Just the physics of the problem.

    Here is a web page with some information and a quick chart that estimates available power based on tower hight (remember power runs with the cube of the velocity--so a little increase in velocity can be a big increase in power).

    If the wind speed near ground is 60% of the speed at XX feet--Then the resultant power will be 0.603 or 0.216 or ~22% of the available power in "good" wind.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • inetdoginetdog Solar Expert Posts: 3,123 ✭✭✭✭
    Re: Vertical Axis
    oglethorp wrote: »
    Just trying to find the best use of a bad location.
    Turbulence will always be an issue but hope to use 100%
    of the 60% available low to the ground without a high pole mount.

    Sometimes the best use of a bad location is not to use it at all.

    If you are prohibited from using a high tower (probably not actually a pole at that height), then small wind may not be economical or useful for you. The 60% figure closer to the ground is based on simple ground-induced reduction in wind speed and some related turbulence. If you have trees and rolling land contributing additional turbulence, you will see far less than 60% with your lower placement. And that is 60% of wind speed, not 60% of power, as Bill pointed out.

    If you have a hard time getting a kite up to 50', then any kind of turbine at 20-30' will be a lost cause. As Bill also said, no amount of clever turbine design can extract power that is not there in the first place.


    A crude but graphic analogy would be from the case of micro-hydro (a much more stable source if you have the right conditions, BTW):

    "I don't have a stream or anything, but there is really heavy fog about 30 feet above the ground. How should I connect my water turbine?"
    SMA SB 3000, old BP panels.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Vertical Axis

    Sorry "oglethrop", but these guys are telling you the truth. I've been there, done that, but with a more efficient horiz axes turbine. It was indeed a pleasure to lay back in the tall grass and "watch the wheels go round", but as to useful charging, useful power production, it was all but useless. It did actually produce useable power twice during it's 2 years in the air, and that was during Tropical Storms that came up the Eastern seaboard of North America, and in total, that was probably 6 hours in that 2 year period. is it still up? No, took it down and except for the alternator, gave the whole thing back to the guy I bought it from and went with more solar.
    As I've said many times: Very few and far between were the days when my home-sized wind turbine produce any usable whatever, but on the other hand, very few and far between were the days when solar didn't produce at least some usable power. Beware! Manufacturers HUGELY inflate the power production claims on small wind turbines, to the point where in my opinion, they should jailed for fraud!
  • ggunnggunn Solar Expert Posts: 1,973 ✭✭✭
    Re: Vertical Axis
    Beware! Manufacturers HUGELY inflate the power production claims on small wind turbines, to the point where in my opinion, they should jailed for fraud!
    When you see "up to", run away! :D
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    Re: Vertical Axis
    ggunn wrote: »
    When you see "up to", run away! :D

    Yeah, it's that magic "up to" that allows them to get away with what otherwise would be fraud, and they know it.
  • peakbaggerpeakbagger Solar Expert Posts: 341 ✭✭✭
    Re: Vertical Axis

    If your site is not suitable for PV, there appears to be some method in Maine where you can lease land on another site and install the PV on that other site but get net metering credit. I am not sure of the details but it may be worth checking out.
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