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3.5Kw turbine
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stumuz1



Joined: 07 Jun 2016
Posts: 340
Location: Anglesey

PostPosted: Sat Jun 08, 2019 3:03 pm    Post subject: 3.5Kw turbine Reply with quote

A neighbour is considering investing in a wind turbine. He wants a 3.5kw machine on an 11metre tower.

Reasons as follows:

Would rather put the money into generating his own electricity than a pension fund, as he does not trust them.

A 3.5 kw is allowed without a DNO (district notice order, asking the grid for permission, they have to do a survey, expensive)

10-11m tower is allowed under prescribed rights(wales), so no planning permission.

So a 3.5kw on a 10-11m tower is basically choose one and go ahead.

I have not kept up with wind power,these last ten years. I have however, read that the price of wind generated power has tumbled and effectively kicked nuclear out as a viable energy source.
I should imagine (I don't know) that the efficiencies have been made in the huge offshore wind farms.

My question is, has the domestic or micro turbines kept up? or are they the same turbines that were available ten years ago?

If anyone was considering a small turbine now, which one would you choose?

Thanks
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clv101
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Joined: 24 Nov 2005
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PostPosted: Sat Jun 08, 2019 3:59 pm    Post subject: Reply with quote

I don't have a lot of positive things to say about small scale, generally unreliable, need to be serviced, unless it's an excellent site, 11m off the ground is just too low to get reliable wind flow.

Do the sums, work out the total cost, including service, maintenance etc over say 10 years, and see how much solar you could buy instead. My bet is that solar will be better and certainly less work.
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stumuz1



Joined: 07 Jun 2016
Posts: 340
Location: Anglesey

PostPosted: Sun Jun 09, 2019 8:30 am    Post subject: Reply with quote

Sage words, Thank you.

Pity really, this part of windy Wales, It's a shame the wind cannot be harvested on a small scale.
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adam2
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Joined: 02 Jul 2007
Posts: 7154
Location: North Somerset

PostPosted: Sun Jun 09, 2019 1:29 pm    Post subject: Reply with quote

Domestic size wind turbines can be most worthwhile, but only in a windy situation.
Unlike PV they need maintenance, as does the supporting tower.

If the electricity demand is for lighting, then wind power produces the most energy at the darkest time of year, unlike PV that is at a minimum just when it is most needed.

For grid tied use PV usually makes more sense unless the site is unusually windy.

BTW, DNO is commonly understood to be an abbreviation for Distribution Network Operator. The organisation that distributes electric power at low and medium voltage to end users.
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stumuz1



Joined: 07 Jun 2016
Posts: 340
Location: Anglesey

PostPosted: Sun Jun 09, 2019 7:58 pm    Post subject: Reply with quote

adam2 wrote:


BTW, DNO is commonly understood to be an abbreviation for Distribution Network Operator. The organisation that distributes electric power at low and medium voltage to end users.


Ahh!

Thanks Adam.
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vtsnowedin



Joined: 07 Jan 2011
Posts: 5223
Location: New England ,Chelsea Vermont

PostPosted: Sun Jun 09, 2019 9:36 pm    Post subject: Reply with quote

adam2 wrote:
Domestic size wind turbines can be most worthwhile, but only in a windy situation.
Unlike PV they need maintenance, as does the supporting tower.

If the electricity demand is for lighting, then wind power produces the most energy at the darkest time of year, unlike PV that is at a minimum just when it is most needed.

For grid tied use PV usually makes more sense unless the site is unusually windy.

BTW, DNO is commonly understood to be an abbreviation for Distribution Network Operator. The organisation that distributes electric power at low and medium voltage to end users.
While the site does have to be windy enough to justify it I can't agree with your concerns about maintenance. Back in the 70's I was on a crew taking down wind generators in the Dakotas and Eastern Montana. They were installed in the 1930's and were still in working condition for the most part other then the original battery array. the 34 meter high towers were galvanized angel iron and in good condition. We did find it faster to snap off bolts by over tightening them to the right one turn as apposed to twenty turns squeaky to the left without having time to spray them with a lubricant. These units put out between 1800 and 2200 watts in a 20 mph wind at 32 volts DC or 110 volts DC for the 2200 units.
The technology of 2019 can certainly produce a unit as durable and maintenance free as those built in 1935 with balsa wood blades and brass bearings.
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BritDownUnder



Joined: 21 Sep 2011
Posts: 539
Location: Hunter Valley, NSW, Australia

PostPosted: Sun Jun 09, 2019 9:38 pm    Post subject: Reply with quote

I don't know the rules but here are my opinions.

Why connect to the grid at all? Just use it to charge batteries and provide lighting Any excess load can be dumped to a hot water or underfloor heating circuit.

Also why a 11 metre tower. I know that the wind speeds are higher up there but so are the speeds when you hit the ground after falling from there. Safety and simplicity. Also why not get two smaller lower turbines attached to the house or garage?
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vtsnowedin



Joined: 07 Jan 2011
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Location: New England ,Chelsea Vermont

PostPosted: Mon Jun 10, 2019 12:16 am    Post subject: Reply with quote

BritDownUnder wrote:


Also why a 11 metre tower. I know that the wind speeds are higher up there but so are the speeds when you hit the ground after falling from there. Safety and simplicity. Also why not get two smaller lower turbines attached to the house or garage?
You want the bottom of the circle swept by the blades to be above any nearby obstruction to the wind including trees and buildings. If not the blades will be hit by different wind speeds between the top and bottom of each revolution throwing it out of balance and adding stress to the bearings.
The minimum tower the Jacob's company used to sell was fifty feet high and most were taller as a little more iron gave a lot more output for the cost.
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adam2
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Location: North Somerset

PostPosted: Mon Jun 10, 2019 3:31 pm    Post subject: Reply with quote

I have installed wind turbines on buildings, but this needs careful consideration and probably special construction on account of the wind loading.

The most recent case was a large new outbuilding built of concrete blocks.
The apex of the pitched roof consisted of a substantial beam that ran the length of the roof.
The ends of this beam protrude about a meter beyond the structure.
The wind turbine is mounted on a vertical steel pipe the bottom of which is set in a concrete foundation. This pipe is clamped to the horizontal beam and thereby braced.

Dimensions, from my imperfect memory
Ground to roof beam------------------4m
Ground to wind turbine mounting----8m

Two turbines are installed thus, one each end of the building, and have given satisfaction.
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stumuz1



Joined: 07 Jun 2016
Posts: 340
Location: Anglesey

PostPosted: Mon Jun 10, 2019 8:01 pm    Post subject: Reply with quote

BritDownUnder wrote:
I don't know the rules but here are my opinions

Why connect to the grid at all? Just use it to charge batteries and provide lighting Any excess load can be dumped to a hot water or underfloor heating circuit.


Yes, and it appears Scottish power agree with you,
https://www.theguardian.com/environment/2019/jun/10/scottish-power-build-vast-battery-improve-wind-energy

BritDownUnder wrote:
Also why a 11 metre tower.


Don't need planning permission.

It seems that whilst the larger wind farms have come on leaps and bounds, the domestic small scale has not.
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Mr. Fox



Joined: 24 Nov 2005
Posts: 660
Location: In the Dark - looking for my socks

PostPosted: Wed Jun 12, 2019 11:01 am    Post subject: Reply with quote

BritDownUnder wrote:
Also why a 11 metre tower. I know that the wind speeds are higher up there but so are the speeds when you hit the ground after falling from there. Safety and simplicity. Also why not get two smaller lower turbines attached to the house or garage?

The relationship between turbine size and it's power output is non-linear:



Roughly speaking, if you halve the size, you'll get ~1/4 of the power, if you double the size, you'll get ~4 x the power.

When it comes to wind turbines, bigger is most definitely better.

Also there's the factor that the higher you go, the wind gets faster and a lot less turbulent.
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BritDownUnder



Joined: 21 Sep 2011
Posts: 539
Location: Hunter Valley, NSW, Australia

PostPosted: Fri Jun 14, 2019 12:19 am    Post subject: Reply with quote

Mr. Fox wrote:
Roughly speaking, if you halve the size, you'll get ~1/4 of the power, if you double the size, you'll get ~4 x the power.

When it comes to wind turbines, bigger is most definitely better.

Yes wind power produced is proportional to swept area of the turbine blades and, I think, the cube of the wind speed. Wind speed also increases by height by some non integer > 1 power as well.
Nonetheless if you feed in to the grid for your 'retirement' income on a fairly low feed-in-tariff you are probably contributing more to the power company's CEOs retirement income more than your own. Climbing an 11 metre tower on the outside is not my idea of a happy retirement. I have climbed down a 95 metre tower on the inside and it is no mean feat.
I would have one on the ridge of the roof any day charging batteries and powering heating on the dump load any day and accept the losses.
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vtsnowedin



Joined: 07 Jan 2011
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Location: New England ,Chelsea Vermont

PostPosted: Fri Jun 14, 2019 10:15 am    Post subject: Reply with quote

Well I agree that climbing high towers and working at heights is a young mans game. Us older and hopefully wiser people need to hire younger people to do the climbing for us. Perhaps the best and easiest plan for retirement energy is holding stock in a company that is successfully building and maintaining wind farms. And yes the area of a circle formula is a wonderful thing. A=R²*π where doubling the R (radius) yields four times the A ( area).
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vtsnowedin



Joined: 07 Jan 2011
Posts: 5223
Location: New England ,Chelsea Vermont

PostPosted: Fri Jun 14, 2019 10:28 am    Post subject: Reply with quote

adam2 wrote:
I have installed wind turbines on buildings, but this needs careful consideration and probably special construction on account of the wind loading.

The most recent case was a large new outbuilding built of concrete blocks.
The apex of the pitched roof consisted of a substantial beam that ran the length of the roof.
The ends of this beam protrude about a meter beyond the structure.
The wind turbine is mounted on a vertical steel pipe the bottom of which is set in a concrete foundation. This pipe is clamped to the horizontal beam and thereby braced.

Dimensions, from my imperfect memory
Ground to roof beam------------------4m
Ground to wind turbine mounting----8m

Two turbines are installed thus, one each end of the building, and have given satisfaction.
How large was the blade circle? If say two meters that meets the need to be well above the building but are there any other taller buildings or trees in close proximity? 8m will certainly work but 11m or 15m in the same location would produce more power. It is just a matter of getting it as high as you can.
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fuzzy



Joined: 29 Nov 2013
Posts: 889
Location: The Marches, UK

PostPosted: Fri Jun 14, 2019 11:34 am    Post subject: Reply with quote

No one considering vertical bearing types? 3 tensioned guylines to buildings or anchor bolts. Maybe a semi flexible ground joint with the guys taking the sideways wind load. Maintenance could be a doddle compared to a high tower.
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