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Indeed 24 MW would be eight 3 MW turbines, which as low-wind turbines with 100-m-plus diameters would need separating distances of nearly a kilometre in the prevailing wind direction – at most half of that would seem more realistic.

Based on the 2,900 TWh-a-year figure, they seem to have considered an average capacity factor of 27.8% (probably realistic if we consider low-wind turbines with high towers), thus an average power of 6.7 MW. Still way above that 1 MW or even the 2-4 MW of local models.

I'll look for the report and check their assumptions.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Wed Jun 12th, 2013 at 03:04:07 PM EST
[ Parent ]
The study is here.

Disconnected patches and strips is indeed the 'solution', check the example diagram on page 31 (you can even have a single tightly-spaced wind farm with the turbines placed on several separated but nearby suitable areas of less than a kilometre across). This also reduces the applicability of the 1 MW/km² figure for large contiguous windfarms.

They used two reference wind turbines (one weak-wind one strong-wind), and an iterated placement with a minimum spacing of 456 m (four times the [larger] rotor diameter of the weak-wind turbine). With a triangular grid pattern on a large uninterrupted suitable area, I calculate 17.77 and 18.88 MW/km² as maximum density on actual land area (as opposed to the area of the patches of suitable land) for the 3.2 MW resp. 3.4 MW reference turbines.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Wed Jun 12th, 2013 at 04:06:16 PM EST
[ Parent ]
Thanks DoDo, looks good.

I found that Jacobson has also studied this problem, arriving at considerably higher average power densities: ~ 4 MW/km^2.

by mustakissa on Thu Jun 13th, 2013 at 03:38:55 PM EST
[ Parent ]

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