Weatherwatch: research finds optimal size for windfarms

It’s always good to see wind turbines going at full tilt on a breezy day. But are more wind turbines always a good thing?

Windfarms come in all shapes and sizes, from one lonely turbine producing energy for a farm, to Gansu windfarm in China, whose 7,000 wind turbines make it the largest windfarm in the world. However, extracting energy from the wind is not straightforward, and new research reveals that there is an optimal size for windfarms.

Wind turbines extract energy from the wind, but their spinning blades also create turbulence, making it harder for turbines situated downstream to extract energy. Enrico Antonini and Ken Caldeira from the Carnegie Institution for Science in California modelled airflow over turbines and looked at different sizes and arrangements of wind farms.

Their results, published in Proceedings of the National Academy of Sciences, show that turbines arranged in rows facing the wind produced 50% more power than those arranged in wind-facing columns. But they also found that these gains were lost after a farm reached around 30km in size, because the drag created by large windfarms slows the wind down.

Curiously windfarms further from the equator could afford to grow larger because wind energy and momentum was better replenished by the Earth’s spin.

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