Advice on vertical axis wind turbine

[thegreenman]

Why are vertical axis wind turbines not seen anywhere whare as standard turbines are all over the place (at least where I live)

Doesn't vertical axis have benefits over standard such as low startup speed and are omni-directional.

Did I miss a whole chapter on wind turbines or something

[russ]

Hi Greenman,

Afraid you missed a chapter. There are numerous reasons VAWTs have not really made it on the market - a few are:

1) They actually start producing power at higher wind speeds. Many turbines claim low wind speed startup of production but under about 5 m/s wind speed there is little power available anyway. Some units require a jacking motor to help them start.

2) Location - wind speeds increase substantially as you raise the turbine above ground level. A VAWT would be difficult to have on a 25 meter stand let alone 50 or 100 meter.

3) One of the claims VAWT people make is that they work better than a HAWT in gusting winds or when the wind is changing direction - sounds nice but not true.

4) Any site making great claims lacks 3rd party testing and most don't offer power curves.

5) Capacity factor is important - meaning what percentage of the year is the turbine producing at it's rated capacity. A well sited commercial wind farm will be anywhere from 20 to 35% - poorly sited can be 10% or lower. If you look at the ads for most wind turbines they take hourly output multiplied by 8760 as annual production - they totally ignore capacity factor as it would show their units are worthless.

6) A great resource for wind turbine information is Paul Gipe's site at www.wind-works.org He is one of the world wide recognized experts in the field.

Russ

[thegreenman]

Thanks Russ,

I knew wind speed increased above ground level, I guess that's why the turbines around here in the Fens are so tall

I guess if VAWTs were as good as the claims we'd see more of them.

Will take a look at that site, thanks again.

[russ]

Wind turbines are interesting and may be useful in the future - when a storage method is actually available - not just talked and dreamed about.

At present they mainly make the primary generators less efficient as the turbines track the wind.

Even in the northwest of the US where there is a lot of hydro they create big problems for the hydro operators plus additional wear and tear on the hydro turbines as they are run up and down through critical speeds numerous times per day while trying to compensate for changing wind generation - that was not in the original design and is not a good thing.

The VAWT type has yet to show any real hope - neat as they seem to be.

Most of the claims are more imagination than reality:
1) low wind speed operation
2) lower vibration
3) mount on the roof
4) low cost per kWh
5) ???

They do make nice stationary lawn ornaments for some people though.

[thegreenman]

The UK is quite a windy country and at the moment there seems to be a fad for building large offshore sites, which I think people prefer to land turbines.

I realise wind is not very consistent (unless you lie i our house) and I would have thought more concentration would be put on tide and tidal power which provides a consistent source of power.

There was talk of a massive project in the Avon but there are many concerns about the effect on wildlife and the coastline.

I do like the idea of the submerged turbines that take advantage of the tide going in and out.

You probably already know about the wave power generators that make use of the up and down motion of the waves.

Yet we still have the problem of transmitting the power and storage.

Where's Tesla's wireless power transmission when you need it

I think 24 hour generation will probably replace the need for storage if a cost effective solution is not found.

Just my thoughts.

[russ]

A few days back someone was talking about the Stansted area. Data is available for the airport area and I was surprised how windy it was!

[thegreenman]

Maybe it got windy after they built the airport

[russ]

You mean as in 'air coming to the port'?

[thegreenman]

Your humour is very dry, I'm shocked that it took this long for the tone of the conversation to be lowered.

Whilst we are in that area have you heard about the urea fuel cells?

That's not a joke BTW.

[mathewrobert]

Hybrid Wind Systems also too good

Hybrid wind system combines solar energy and wind energy (combination of two or more renewable energy systems). Hybrid wind systems are systems that use wind energy and another energy source to provide for a building's energy requirements. Most hybrid wind systems will use a secondary renewable source of energy such as hydropower or solar energy.

[russ]

Hybrid wind system combines solar energy and wind energy (combination of two or more renewable energy systems). Hybrid wind systems are systems that use wind energy and another energy source to provide for a building's energy requirements. Most hybrid wind systems will use a secondary renewable source of energy such as hydropower or solar energy.

1) People who have a location proper for hydro are few and far between.

2) This was a VAWT thread and that type of wind turbine has proven to be near useless.

This is not providing useful information to the members but simply copying a blurb from somewhere, pasting and attempting to drop a link.

Russ

[petset77]

Vawt

three years of research for my offgrid application brought me into VAWT territory. the best argument against them i have read about via my own inquiries deals with potential over-revving. there isn't a way to efficiently furl them in high wind situations. efficiently is the key word there. plus, a lift force machine deals with large and complex forces (and affiliated system cost), thus many of the newer or home buildable systems are drag (wind speed and less) powered. over sizing the turbine, and mechanically increasing the rpms with belts/pulleys or gearing is a simple remedy, but other problems exist. the technology didn't seem to be suitable for my application. that said, i keep an open mind to newer and/or other technology that i am not familiar with.

[russ]

Just the fact that they are close to the ground is the death of a VAWT in most locations.

The turbine needs to be up in the better and more steady breeze/wind. Not down on the ground where there are too many obstructions.

Russ

[petset77]

Vawt

totally agree- and it holds true for any wind driven apparatus. i see horizintal turbines on 15-20' poles, or attached to the soffit on a house. most of these people are not happy with the output of their generators. i have seen vawts set up high, but the other issues remain.