alt.energy.homepower

nicksanspam@ wrote:

> Eeyore wrote:
>
> >> >I phoned the Met Office. The daily average yesterday for NW10 was 9 knots
> >> >or m/s. At that speed those turbines might be providing maybe as much
> >> >as 500W ea (absolute maximum).
> >>
> >> P=kV^3.
>
> The point was that you can't use the average windspeed.
> Use the average of its cube or a Rayleigh distribution.
>
> >What's your value for k ?
>
> Paul Gipe's Wind Power book says wind power density is ^3 W/m^2,
> with V in mph. He says the best rotors achieve 40% efficiency (vs the 60%
> Betz limit... 90% efficiencies for the transmission, generator, and power
> conversion would make the power density ^3 W/m^2.

617W theortetic at @ 9 kots and dia.

247W recoverable.

Graham