Can anyone familiar with wind generation technology explain this to me?

[TygrBright]

Why does so much of this technology rely on what looks to me like a stupid, inefficient, and dangerous design? The big "bladed-fan" style turbines appear ubiquitious.

Wouldn't the vertical spiral-type turbine be more efficient, and potentially safer for bird life, as the the turbine could be economically screened?

What gives?

curiously,
Bright

[dipsydoodle]

1. I'm sure that anything which would overcome the gearbox problems wpuld be welcome

They've yet to come up with one which really is up for the job.

[TygrBright]

2. If the gearbox is located at the base of the unit...

...and the unit's wind-facing surfaces are connected all the way from the base to the top of the central axis, the base could be series-connected with multiple turbines. I would think that could yield very high efficiency and allow gearbox design to accommodate lateral as well as vertical stress.

But I will admit that my understanding of the mechanics is limited, at best.

It just strikes me as the kind of simple engineering challenge that should have been resolved by now.

frustratedly,
Bright

[madokie]

3. Maybe they need to work on lower speed generators so they don't need the gear box

I think they should use hydraulics to do the job rather that gears. They could put the generator on the ground where it would be easy to deal with and have a pump up in the tower connected to a hydraulic motor at the generator end. You can actually get the rpms you need like this by sizing the pump how ever many times larger than the motor so the motor would spin at a much faster rate, same as what you get using gears in a gearbox. If they keep the piping between the turbine/pump and the motor/generator large there wouldn't be much losses in piping either.
If they're going to be using vertical axes turbines anyway.

I built a small vertical axes turbine years ago to get a feel for what you can do with the wind but I don't really live where there is a lot of wind 24/7 so I've not pursued it but in that experiment I seen that the potential is definitely there.

[muriel_volestrangler]

4. A horizontal axis sweeps a far larger area

and is thus more efficient, per support. The blade is always at the optimum angle to the wind; while a vertical axis one is constantly changing angle, and you wouldn't be able to design it to get the most force all the way round the rotation. You have to build more vertical-axis turbines to get the same power.

However, there is a project that thinks that arranging contra-rotating vertical axis turbines will help prevent turbulence downwind, which means the turbines can be sites closer to each other: http://www.bbc.co.uk/news/science-environment-14452133

This may be more efficient, in terms of land area, even if you have to build more turbines.

[OKIsItJustMe]

5. Look ma! No gearbox!

http://www.technologyreview.com/energy/23517/

[font face=Times, Serif][font size=5]GE Grabs Gearless Wind Turbines[/font]
[font size=4]New direct-drive turbines promise to lower the cost of offshore wind energy.[/font]

Wednesday, September 23, 2009 | By Prachi Patel

[font size=3]With a new purchase, GE is betting on an early-stage turbine technology that could make offshore wind farms cheaper to maintain. The acquisition of ScanWind, based in Trondheim, Norway, has also secured GE a foothold in the growing offshore wind energy market.

Instead of gearboxes, ScanWind uses a novel direct-drive generator technology in its 3.5-megawatt turbines. This makes the turbines more reliable, the company says, by cutting downtime and repair costs--an especially important consideration for turbines offshore, where it's more expensive to send technicians for maintenance. ScanWind has been testing the turbines on the Norwegian coast since 2003.

GE, based in Fairfield, CT, is the world's second-largest maker of wind turbines, with more than 12,000 turbines installed globally. But GE's offshore wind energy portfolio has been minimal so far, and the company wants to expand its offshore offerings. By acquiring ScanWind, transferring its expertise and understanding of onshore wind, and adding technologies such as remote monitoring and sensing, GE hopes it can make a solid, cost-effective offshore wind product.

In conventional wind turbines, the blades spin a shaft that is connected through a gearbox to the generator. The gearbox converts the turning speed of the blades--15 to 20 rotations per minute for a large, one-megawatt turbine--into the faster 1,800 rotations per minute that the generator needs to generate electricity. "Wind turbines are very different than any other gearbox application," says Sandy Butterfield, chief engineer of the wind program at the National Renewable Energy Laboratory in Golden, CO. "You're going from a very low speed to a high speed." Typically it's the opposite.

…[/font][/font]

http://www.controleng.com/single-article/direct-drive-wind-turbines-flex-muscles/4be132ffb0.html

[FBaggins]

6. They're ubiquitous for a reason. It's usually the best option.

Remember that the wind is the key component... and it tends to be steadier and stronger a couple hundred feet in the air than closer to the ground (with some exceptions). Put the center of mass of a verticle-orientation model that high in the air and you're not really gaining efficiency.

I also don't see how they're "dangerous". Like anything else, they can break and they are not 100% without risk, but the risk is not excessive for the rewards.

[FSSF]

7. It could always be a case of technological lock-in.

Like with light water reactors, they're not built for being the best design anymore, just the easiest to get built.

[happyslug]

8. Here is Wikipedia's comment on Vertical wind turbines

"The key disadvantages include the low rotational speed with the consequential higher torque and hence higher cost of the drive train, the inherently lower power coefficient, the 360 degree rotation of the aerofoil within the wind flow during each cycle and hence the highly dynamic loading on the blade, the pulsating torque generated by some rotor designs on the drive train, and the difficulty of modelling the wind flow accurately and hence the challenges of analysing and designing the rotor prior to fabricating a prototype.

http://en.wikipedia.org/wiki/Wind_turbine


The more I looked, the more it seems that traditional wind turbines are used for two reasons:

First is traditional blades have the POTENTIAL to produce more power do to the ability to make the blades bigger, bigger blades mean higher speed the blade turns, with the same wind speed, thus the less gearing needed to generate electrical power.

Second, it is the easiest to sell to investors, for you can show investors existing ones.

Vertical Turbines have problems, the first is it is more expensive to build for the same size in height AND at the same height will turn less in the same wind thus needing more gearing to produce the speed to generate electrical power. i.e more expensive to build for less power.

The vertical turbine have some advantages, for example the gearing can be on the ground as opposed in the tower. Given their slower speed kills less birds and bats (through this is more a claim then a fact, the way most birds and bats are killed is they see a blade do down and follow it, but then the second blade comes up from behind hitting the bird or bat. If you have several blades instead of just three it is harder for the bird or bat to miss the other blades. Easier to install more blades on vertical turbines but at an increase in cost AND weight, the increase weight slows down the vertical turbine even more).

Some web sites on wind turbines:
http://www.builditsolar.com/Projects/Wind/wind.htm

Another way to look at this problem, VAMT means a "vertical axis wind turbine":
But with a VAWT, the swept area is a cylinder perpendicular to air flow. As such, part of the “swept area” is working, while part is simply being blown around, not at an optimal angle to generate lift. This results in a VAWT rotor that is less efficient than a horizontal axis rotor....

Anything with an airfoil, ideally, can be 59.3 percent efficient. In reality, a horizontal axis turbine operates somewhere around 35 percent. A vertical axis turbine is lower, maybe attaining 30 percent, which doesn’t sound like much, but other factors such as increased maintenance and lower energy production add to the difference

Read more: http://www.motherearthnews.com/Renewable-Energy/2008-02-01/Wind-Power-Horizontal-and-Vertical-Axis-Wind-Turbines.aspx#ixzz1jW2qmVN2

http://www.motherearthnews.com/Renewable-Energy/2008-02-01/Wind-Power-Horizontal-and-Vertical-Axis-Wind-Turbines.aspx