Photo of the wakes of offshore wind turbines, and discussion of effects on efficiency

[muriel_volestrangler]

First, the photo of the wakes - can we call them contrails?

http://ict-aeolus.eu.nyud.net:8080/images/horns_rev.jpg

And a technical paper analysing the effects of the wakes in the array of turbines at Horns Rev off Denmark: http://www.dongenergy.com/SiteCollectionDocuments/NEW%20Corporate/PDF/Engineering/40.pdf

Via the Sustainable Energy - Without the Hot Air blog

[bbinacan]

1. Cool picture.

Maybe they should stagger their placement.

[muriel_volestrangler]

2. But the wind direction isn't constant

The paper even points out that over the whole array, the direction isn't even necessarily the same at each edge at any one moment. They do say that the losses aren't so bad when the wind direction isn't parallel to the rows.

There might be some worthwhile work for a mathematician to come up with a pattern so that even if some turbines line up and you get some loss, then others won't, whatever the wind direction. Or perhaps there should be no pattern at all - as amorphous as possible?

[bbinacan]

3. I like the

no pattern idea.

[eppur_se_muova]

8. Um ... also known as the "maximum navigation hazard" idea.

Keep them in neat rows. Less likely for boats to hit them.

[kristopher]

9. Placement is a thoroughly studied issue.

Many, many billions have been spent on wind farms - I assure you the issue of placement is always part of the evaluation.

[muriel_volestrangler]

10. Part of it, but it seems it's not just efficiency taken into account

For the Codling Wind Park off Ireland:

Five alternative layout types were considered. These varied from computer optimised layouts
which maximised wind energy yield, but would appear as random patterns of turbines to
onlookers, to formal square grids and offset grid pattern layouts. A number of other patterns were
used including hexagonal patterns, and grid patterns with gaps in rows parallel to the wind to
increase yields of downwind turbines.

The energy optimised layouts were considered not to appear harmonious and were discarded,
despite having the highest energy yields.

The offset grid pattern was considered by the landscape consultant after careful consideration, to
have distinct visual advantages over the others. This layout, even when compact to reduce
horizontal extent of the wind farm yet further, allowed sufficient space between rows of turbines to
allow some views through ‘avenues’ of turbines to the horizon when viewed from most
perspectives. This was not true for the formal grid based layout or the hexagonal layouts which
presented ‘walls’ of turbines from most viewing positions. The offset grid pattern also enjoyed
reasonably high energy yields.

A compact offset grid layout laid out in block form with north/south extent reduced as far as
possible, to minimise horizontal extent when viewed from the coast, was selected as the
preferred layout for the Codling Wind Park. This was felt to minimise landscape and visual
impacts as far as possible and allow for positive visual effects, while at the same time having a
relatively high energy yield compared to other compact layout types.

http://www.codlingwindpark.ie/downloads/Codling-Non-Technical-Summary.pdf

Which will be 13km ofshore; Horns Rev is 14km.

[kristopher]

11. That's right.

The biggest factor is spacing distance to reduce the torsional forces from turbulence that affects the shafts longevity of trailing turbines. Once that distance requirement is met, the rest is based on prevailing winds and, as snip says, aesthetics.
It is much more complex when it a terrestrial or near shore farm as the landscape affects airflow.

[shraby]

4. Sure looks photoshopped to me.

[thunder rising]

5. This is a situation were dew point and temperature are very close and the slightest turbulence fogs

Nothing to worry about

[NNadir]

6. Gee. I hope it doesn't cause anyone to collide with Denmark's offshore OIL and GAS rigs.

Were it not for oil and gas, which Denmark has no intention of phasing out, Denmark would have an energy problem other than greenwashing its true agenda.

http://www.ens.dk/en-US/OilAndGas/Sider/Oilandgas.aspx

[TxRider]

7. What a cool pic

Wonder how long they had to wait for weather and wind direction to both line up for that to happen?