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Actually I am not sure their calculation works.

They have 49,400 square km of suitable area, and want to build 1190 GW of capacity on that. That's by my calculations 24 MW / km^2. Which would produce some 8 MW on average per km^2.

I have seen one study using general circulation modelling, showing that you cannot efficiently extract more than 1 MW for every km^2. So there's a discrepancy of 8x.

Now of course if the suitable areas don't form big blocks but disconnected patches and strips, it won't be that bad.

Perhaps not yet give up on offshore ;-)

by mustakissa on Wed Jun 12th, 2013 at 01:42:49 PM EST
[ Parent ]
What's truly stupid about the questioning of feed-in support for off-shore is why we are having the debate now. As things stand, the 10 GW target for 2020 will probably be missed by a large margin due to the start-up difficulties, thus it's too early to speculate on a significant price effect (of any kind) due to the high off-shore wind feed-in rates. We should have this debate in 2018 or so (when the degression of those feed-in rates for new installations is currently set to kick in), when we can see whether serious cost reduction potentials became visible.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Wed Jun 12th, 2013 at 02:46:41 PM EST
[ Parent ]
For a better picture of what we are talking about in terms of feed-in rates, I prepared this diagram:

The first 12+ years and first 8+ years are alternative remuneration models which wind developers can (and have to) choose from. (The diagram ignores bonuses for system integration – granted above the base rate from 2009 to 2014, degressing from 0.5 €-cents/kWh – and repowering – above the rate for the first 5+ years, also degressing from 0.5 €-cents/kWh.)

For comparison, here are the highest and lowest feed-in rates for photovoltaic solar (with projected rates for Q3 and Q4 2013 with the assumption that degression remains the same):

(This diagram ignores a 5 €-cents/kWh bonus for façade-integrated facilities granted between 2004 and 2008 and [lower] rates for electricity not fed into the grid but metered as own use, granted between January 2009 and March 2012.)

The feed-in rate for the smallest rooftop PV facilities can be compared with the industry association's quarterly module price index:

The same on a logarithmic scale:



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

by DoDo on Sat Jun 15th, 2013 at 06:09:26 AM EST
[ Parent ]
would almost deserve a diary of their own...

Wind power
by Jerome a Paris (etg@eurotrib.com) on Sat Jun 15th, 2013 at 08:54:22 AM EST
[ Parent ]
The Q3 solar FIT degression and price index numbers are coming up in July. If a suitable news to tag it to presents itself then, I'll put the updated graphs into a diary.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Sat Jun 15th, 2013 at 09:18:29 AM EST
[ Parent ]
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 ]
My current rule of thumb is that you can pack at least 10 MW per sq. km.
You need 7-8 rotor diameters in the prevailing wind direction, but can get away with 5 in the other direction.

With current rotors around 110-130M for 4-6MW turbines, you can have 2 per sq.km.; with the coming generation (150m rotors for 6+MW turbines), you'll get more or less the same)

Wind power

by Jerome a Paris (etg@eurotrib.com) on Sat Jun 15th, 2013 at 05:35:54 AM EST
[ Parent ]

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