A new twist for wind power technology

[skids]

Well, I wouldn't call it "new" just that modern engineering is finally getting around to having a crack at vertical exis wind turbines.

Wind turbines have long been fixed in the public imagination as giant propellers on sticks, marching across rural landscapes to the ire of local residents. But now an alternative design of turbine that rotates on a vertical axis is attracting renewed interest, as developers consider the benefits they may bring in terms of reduced noise, increased efficiency, versatility and aesthetics.

The horizontal axis wind turbine that resembles a traditional windmill has been the preferred choice of the wind energy industry ever since the world began to awaken to the potential of renewable energy sources. Its rival design, the vertical axis wind turbine was eschewed as inefficient and prone to technical faults.

Now, however, the VAWT may be entering its renaissance period, as experts reconsider its various merits. From a technical standpoint, VAWTs have the advantage of needing no mechanism to turn it into the wind, while any generator or gearbox can be fixed to the ground rather than being fitted further up the tower as in a HAWT. Additionally, VAWTs may not require a tower, which will please the anti-turbine lobby enraged by the presence of 100-foot HAWTs casting shadows across precious rural landscapes.

http://www.upi.com/Energy/view.php?StoryID=20060317-110327-5488r

TMA, one of the companies referenced in the article, put up a website a couple months ago -- it's still pretty basic, but the PDF there is worth reading for the engineering-inclined.

http://tmawind.com/

[MADem]

1. Here's another article on the subject (with pictures)

http://www.memagazine.org/backissues/jun04/features/apptowind/apptowind.html

[TreasonousBastard]

2. I remember these from the '70s, and...

built a little Savonius system that sort of worked, and there were all sorts of kits around. Main advantages were that it was cheap and easy, but even the best Savonius systems were among the least efficient.

Darrieus seems to be a dead end-- they are marginally more efficient than some other systems, but require a startup motor and the stresses seem to be too much to deal with in a practical system.

[ladjf]

3. This type of generator could be mounted on the four corners of

all tall skyscrapers. The venturi effect caused by the geometry of the building shapes as they line the city streets would offer great opportunities for the corner mounted devices. Also, horizontal
turbines on the roofs could be possible as well.

[Ready4Change]

4. They will need towers.

Wind is simply steadier and stronger up and away from the ground.

HAWTs also have the potential to adjust blade angle, decreasing their vulnerability to excessive winds. That is more difficult with most VAWT designs.

I recall VAWTs being promoted as replacements for sails on sailboats. They neglected to consider the reasons that sailors sometimes need to bring the sails down. Hard to do that with a solid mechanism.

I'm not poo-pooing the concept. Just saying it's not all peachy.

[phantom power]

5. I second that.

Industrial wind will always use towers, to obtain more consistent wind.

[skids]

6. It's a trade-off.

The cost of the tower/permitting/etc versus the benefit of the extra power. Certainly a VAWT can use a tower to great effect, but in places where land is not an issue it may be a better bang for the buck to just install more surface-level VAWTs.

As far as high winds, you'll note from TMA's page that their unit can withstand much stronger winds than a HAWT before it has to be idled. (You may also note the efficiency figures, which was the whole point of the article -- even a savonius can compete with HAWTs on efficiency when properly engineered. Not that efficiency is always the most important parameter, FWIW.)

It's a classic case of an optimized product being pitted against one that hasn't been optimized, without anyone with any clout saying "well, hey, what if we optimized the other product?"

[eppur_se_muova]

7. Thanks for the links. I hadn't seen anything about this for years. nt