Race to design world's biggest offshore wind turbines

[Aurora]

The Guardian - 26/07/10



British firm to design mammoth offshore wind turbines with 275m wingspan that produce three times power of standard models.

Article continues ...

[RenewableCandy]

The VAWT story is long and interesting and full of Heath-Robinson-type objects none of which has ever looked to me like a goer....except this one. I hope they're trying out some small ones first...

I'm not sure their rivals, who are building a 10 MW conventional-shaped WT, will get it to fly (sotospeak!): At such huge sizes, the stresses on the blades become unmanageable (apparently). Unless, of course, they've somehow found a way round that, perhaps ultra-light blades?

[emordnilap]

Time to look again again at VAWTs?

They always face into the wind, have unvarying gravitational stress and a much lower centre of gravity. They can be placed further out to sea, too.

So now the obvious question arises: why have VAWTs not yet been used if they are so advantageous? The main reason is that it is still a new technology. Although researchers have looked at vertical axes for decades, the technology fell behind due mainly to material and bearing system limitations.

Investors still see the known technology as a safe bet and even when looking at deep-sea wind they have been more inclined to support horizontal-axis turbines on floating platforms.

However both governments and forward-thinking companies are now investing in the potential of VAWTs for deep sea offshore wind.

[BritDownUnder]

I looked at buying a 1kW VAWT from a popular online ecommerce website for my house and to supplement the solar. However I ruled it out for a variety of reasons; low windspeed area, lack of predicability (after all Australia is pretty sunny and I get 2800 hours of sunshine per year), possibly Nimbyism from neighbours and the fact they think I would be a bit weird, solar is very popular here but I have only seen one wind turbine in a 'suburban' location.

I think the utility size VAWTs have a lot of merits but there must be a reason why people went for HAWT but I do not know it.

[kenneal - lagger]

HAWT in urban areas and on house roofs aren't worth the bother. You're very unlikely to get your money back in the lifetime of the machine. A friend did his MSc thesis on this and found that you would have to put in on the roof of a tower block to get any kind of return. The eddies set up by all obstructions mean that a HAWT is hunting for the wind for too much of the time.

There weren't and probably still aren't enough VAWTs to make a similar study worth while at the moment. They don't suffer from the hunting problem but the wind speed is still very low in urban areas unless you are at the crest of a ridge or have a very tall pole to put it on to get it into free air.