EEVblog #1271 - 100kW WindWall Generator BUSTED!

A 100kW wind generator in only 7sqm? Less than 2% the size of traditional wind turbines!
Basic physics and the whiteboard to the rescue!

A look at the claims of the AmericanWind WindWall "turbine" wind power generator.
And a Wind Power 101 tutorial on how wind turbine calculations work and pesky limitation of Betz's law.

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[flymypg]

That V^3 term builds fast, so 47 MPH (21 m/s) takes the ideal power up by nearly an order of magnitude. To a bit under 20 KW. Still nowhere near 100 KW.

[copernicofelinis]

The laws of thermodynamics should be abolished. All they do is standing in the way of true progress

[moonwalker]

A: Recently, Japanese invented a 20 liters gasoline canister.
B: That has been invented 100 years ago.
A: Yes, but this one fits in your back pocket.

[dan_loup]

"it doesn't matter how many blades"
Gillette will gladly try to prove you wrong.

[kilrahvp]

Betz's law also incorporates the fact that the theoretical max would mean wind speed behind the turbine is 0, which is obviously not possible

[gusbert]

Two wind turbines are standing in a field and one asks the other, "What kind of music do you like?"
The other says, "I'm a big metal fan"

[garethevans]

It takes only 55watts for a fan to move air 13.4mph, which also means you cannot generate more than 55watts from 13.4 mph wind (this is before taking losses into account).

For fun, I worked backwards from a 225cm (8.86 inches) ducted fan. (ebmpapst W1G 200-HH77-52 for those playing along at home) : 1090m^3/hour = 0.3m^3/sec, which comes to 6m/s (13.42mph). That's using only 55watts! So you can NEVER generate more than 55watts from 13.4mph of wind!

Also tried one of my PC's fans, an Arctic Cooling P14 (140mm, 123m^3/h @ 1700rpm), which comes to a little under 2m/s (4mph), but that uses less than 1 watt! So while the blades may rotate at that speed, it doesn't mean it will produce usable energy. This also means that one of those turbines can never generate more than ~3 watts (~3 times the area) in 4mph wind, plus they'll be lucky to get a single watt from their crude 3D-printed impellers.

50watts from 15mph wind would be more reasonable (with near perfect efficiency), not a kilowatt! Maybe if the wind is 140mph you could generate a kilowatt, but then you have bigger problems...

How did this guy get investors?

[OldBenOne]

@ 6:23 "It actually increases the wind speed." So: you line them up one behind the other and free energy, perpetual motion here we come.

[berniwa]

Getting 1kW on such a wind turbine is easy!
1) Attach a voltmeter across the output and measure
2) Attach an ammeter across the output and measure
40V (as seen) x 25A = 1kW - really easy ;-)

[AndreasIndustriePro]

the reason why there is a limit to a wind turbine efficiency is that air has to leave the fan again
imagine extracting 100% of energy from the air, this would mean that the air slows down to 0 and therefore is not leaving the fan anymore.
Since preassurizing air costs energy, the air has to leave the fan with a remaining amount of energy

[MarkTillotson]

Someone doesn't know the difference between a compressible flow and an incompressible one, eh? Mr Yost? Jet engines deal with compressible high energy flows, not a f£%$%ng breeze!!

[anthonyscarnici]

As a fellow engineer, I live for these debunking videos. Keep them coming!

[interstellarsurfer]

Ahh, when the engineer gets kilowatts and milliwatts confused. 😂

[gregwolking]

I'm waiting for the next "miracle" invention that's *so* incredulous that Dave's voice actually goes ultrasonic. ;)

[niceguy]

When you receive the CEO of the year award from Austin Powers.

[trevorlambert]

"the device went through 39 revisions to arrive at version number 40" Wow, so 40 comes after 39? Tell us more, Mr. journalist man!

[LEKProductions]

News report 19:32 "The device went through 39 revisions in order to get to version number 40". Golden!

[anzaca]

1:54 The Patent Office don't have to verify if something works, just that it hasn't already been patented.

[uwepolifka]

I think the problem is the "k" and nothing else. Remove the k from kW and it fits perfect.

[kevinmartin]

Maybe they're multiplying the open-circuit voltage and the short-circuit current and figure this gives the power produced.
This is the flaw in the analysis of so many of the crackpot energy schemes...