Offshore Wind: Turbine Spacing Is Tricky

With wind-power production continuing to spread, we’re seeing researchers and engineers delving deeper into how to boost efficiency. A new report from the consultancy Wind Energy Update points to offshore wind-power turbine placement as a big factor – mirroring a recent report from Caltech scientists working on the land.

The key factor in both cases is the wake effect – the way that a rotating turbine and its stand will cause air turbulence, reducing wind velocity for the turbines around it. Or as the Wind Energy Update report’s author, Alan Tricklebank, put it: “The prevalence of wake effects defines a shadow area in which the energy capture of a downwind turbine would be reduced and its fatigue loading increased.”

offshore wind power, turbine placement

image via Shutterstock

Still, ensuring each turbine is completely undisturbed by those around it can be financially unwise. Widely dispersed turbines translate to more occupied seabed; the probability of varying water depths; and increased transmission requirements – all factors that could drive up costs. In the end, “the trick is knowing how to strike the right balance,” Wind Energy Update says.

“The full restoration of the wind from these effects may take 20 rotor diameters or so,” Tricklebank says. “Given that there are costs attached to the area occupied and the transmission distances, it is economic to trade off performance losses against savings in other costs arising from the reduction of the spacing from the aerodynamic ideal.”

Pete Danko is a writer and editor based in Portland, Oregon. His work has appeared in Breaking Energy, National Geographic's Energy Blog, The New York Times, San Francisco Chronicle and elsewhere.