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Offshore Wind: Much More Expensive Than Previously Thought

offshore wind wake effect

Trying to work out how close together you can pack turbines in an offshore wind farm is a vital engineering decision for the developers of offshore wind farms.

That’s because the turbine wake — the slower and turbulent air that has just passed through the turbine — can reduce the output of any downwind turbines. [bold, links added]

As turbines become bigger, their wakes become much larger, and so, over time, engineers have been advising larger and larger spacing (Figure 1).

But the engineering models are, well, models, and each time a new, larger generation of turbines is introduced, they enter terra incognita: a scenario that is outside the range of their calibration data.

Inevitably, they sometimes get it expensively wrong.

The Burbo Bank Extension wind farm is currently paying over 5% of its turnover to next-door Burbo Bank Windfarm in compensation for wake losses.

Now, an important new working paper from renewables consultants ArcVera is reporting that the wake effects behind the huge turbines that are now coming onstream are going to be much worse than previously thought.

The conventional engineering wisdom is that there will be a 10-15% loss of output for a turbine placed less than 2 km downwind of another.

ArcVera is suggesting that new wind farms could experience losses of as much as 25% at a distance of 10 km(!).

The paper is another model, so it too needs empirical validation, but if it’s right, the implications are very serious for wind farms coming on stream.

Turbines are going to have to be spaced much further apart, and wind farms are going to need to be further apart too.

This is just going to increase the cost of an inherently expensive technology still further. And taxpayers are going to foot the bill.

Read more at NZW

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