A proponent of the wind turbine shown at left writes:

I commented this 6 year’s ago . It is so simple even if you put in small stream 1 000 000 small turbines like this one, you will have more power. It’s the same for the wind , we don’t need this big huge wind Parks we need small efficient and most important easy for fixing and easy for installation. Not forgetting we can make smaller things with eco friendly materials.

Me:

There are a few reasons that claims like this are bullshit. The main one is that the power extracted from the wind is proportional to the square of the radius of the blades.  We recall from our childhoods the formula: Area (of a circle) = pi r-squared.  This is why real (not fictional) wind turbines are so large (and getting larger all the time).

Also, as I mention frequently, today’s wind turbines capture about 90% of the theoretically available kinetic energy from moving wind; given the laws of physics, there is no room for any significant increase in efficiency/output.

Even if neither of these were true, which would you rather cover the cost of maintaining: one large turbine or a million little ones?

The Case for Tiny Wind (or Hydro) Turbines