1. ## Anyone know anything about windmills?

around how much energy do you think a typical windmill with a diameter of about 10 feet for the blades could produce in 10M/S winds? or about 20MPH winds?

I'd like a number in watts/KW.

2. Do you have the constants?

The power from windmills

3. nevermind I figured it out, it's about 2.2kilowatts. which is very interesting considering I saw a certain windmill produce about 4KW. The 2.2 KW figure is of the average windmill running about 59% efficiency and according to the figures the one I saw was 106% efficient? wow I'm excited now.

4. :eek:

The design of the windmill (and presumably the air velocity) will affect the amount of power it is possible to make.

Not sure why they would usually make a design that was less than optimal unless (1) older designs, (2) a given design is only useful for certain wind speeds, or (3) the less powerful designs are more economically efficient.

Ed: Not sure about turbines, but it's pretty hard in process engineering to get any equipment running at say 99% efficiency. Some types of operations are better than others. Power generation tends to be pretty low.

5. There are wind energy converters with a gearbox and without. Cause you said windmill, I assume you mean the classical wodden windmill (so I assume without a gearbox, there is nevertheless a transmission, especially with the classical windmill on a huge scale).

Therefore the formula is:

P_el = 1/2 * A * rho * v³ * eta (* i )

with being:

P_el = electrical performance (Watts)
A = Area (m²)
rho = density of the medium used for propelling (around 1,2 kg/m³ for air at 68 degree Fahrenheit)
v = velocity ( m/s)
eta = energy conversion efficiency (percent, no unit)
i = transmission (percent, no unit)

There is something called the Betz Coefficient. It says that, if the kinetical Energy of the wind is used to propell the mill, there is a limit for its usage, cause the wind would theoretically have to stand completly still after hitting a blade if the Energy conversion efficiency was to be 100%.

So according to Betz law, the maximum of usable Energy from the Wind is: 59,3 %. A classical wodden windmill has a energy conversion efficiency of maybe 10 - 30 %, depending on its configuration. Best way to measure it is to measure the electrical output it generates and then enter the numbers in the equation above and compare for the energy efficiency.

In your case, I would assume (with 10 feet blades being = 3 m in length and assuming 0,5 m in width = 1,6 feet , and an energy conversion factor of 25%) :

P_el = 1/2 * (3 * 0,5) m² * 1,2 * 10³ * 0,25 = 225 Watts

Here you can read in detail about it (article is quite good):
Wind turbine - Wikipedia, the free encyclopedia

6. The windmill I was talking about is a special new type of windmill, 59% is about as efficient as most modern windmills get nowadays, and I meant that both windmills have the same size propeller and same wind velocity, but produce different levels of electrical output. So obviously this new windmill is almost twice as efficient as the best ones we are using today. This is revolutionary.

The simple fact is, that I saw a windmill with a 10 foot diameter propeller in 23 MPH winds produce 4 KW. No other windmill can currently do this. oh I should probably mention the secret has to do with the generator inside the windmill.

7. Ya, gearbox development is a current issue which is even funded with money from the country.

8. Sounds great What stage of the R&D process are they currently at? Are they using one commercially already?

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