[kaliszad]

Does anybody have good data on how size improves usage and efficiency? I would ideally like to see statistics of how large a turbine hits what power output during a year.

I imagine a very large turbine like this could run almost always in an off-shore wind farm but at what power output? This is quite important for comparisons to other sources of energy. Even nuclear power plants don't run for much more than 85% of days in the year (at least Temelín in Czechia)

[wcoenen]

> how size improves usage and efficiency

The power of a wind turbine scales linearly with the swept area. The swept area scales as the square of the height.

Furthermore, wind turbine power also scales with the third power of wind speed, and wind speed goes up with height (though not linearly).

So you can see why the physics of the problem are strongly incentivizing size increases.

[Scipio_Afri]

I don't know of any data but the following fundamentals are driving this:

"The equation for wind power(P) is given by P= 0.5 * ρ * A * Cp * V^3 * Ng * Nb where, ρ= Air density in kg/m3, A = Rotor swept area (m2).Cp = Coefficient of performance V = wind velocity (m/s)Ng = generator efficiency Nb = gear box bearing efficiency."

http://www.ijsrp.org/research_paper_feb2012/ijsrp-feb-2012-0...

Area, A, is equal to pi * r^2. As you increase your radius (length of the wind turbine rotor) it grows exponentially due to it being squared.

The consistency of the wind offshore, plus the higher speeds, is what is driving offshore due to the Velocity of the wind contributing to the power output being cubed.

Also see: https://mmpa.org/wp-content/uploads/2015/09/Swept-Area-Provi...

Some turbines do not use a gearbox, so replace that with the efficiencies of magnetic gearboxes also called "direct drive" turbines.

There are some other advantages to wind power as well compared to gas power, such as being able to respond more quickly to grid power dynamics such as voltage droop and frequency response.

Regardless even if some of the power is being thrown away because the grid doesn't need it, the fuel is at zero cost. It does bring up interesting maintenance and other questions. As far as I understand, you can have the wind turbine locked to prevent spinning and do that for say 50% of the wind park. So that should prevent the excessive wear and tear on the electrical components, and minimize things like loads on the foundation and structure itself.

[lazylizard]

why 2 blades not 5?

[Nokinside]

It's 3 blades not 2.

3 is the optimal between wind area and turbulence.

[TheMblabla]

I don't have numbers but generally, compared to smaller turbines, a larger blade length means a faster blade tip to maintain the same rotational frequency (the end of the blade will be going faster around the turbines circumference). This creates more noise, and noise is a HUGE limiting factor, so they increase the turbine's torque to get more power from slower rotations. That means a larger, more complex, and more expensive generator in upfront and maintenance cost.