[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.