Consider the design of a home-built wind turbine using a 350-W automobile dc generator. The goal is
to deliver 70 kWh in a 30-day month.
a) (10 points) What capacity factor (CF) would be needed for the machine?
b) (10 points) If the average wind speed is 5 m/s, and Rayleigh statistics apply, what should the rotor
diameter be if using the CF estimating equation in Eq.12.6 (also as below)?
CF = 0.087Vavg − PR/D2
where CF = turbine capacity factor
Vavg = average wind speed (m/s) assuming Rayleigh statistics
PR = rated power of the turbine (kW)
D = rotor diameter (m)
c) (5 points) How fast would the wind have to blow to cause the turbine to put out its full 0.35 kW if
the machine is 20% efficient at that point. Assume a standard air density of 1.225 kg/m3.