US scientists have worked out how to extract 33 per cent more power from an offshore wind farm: stagger the turbines rather than line them up in neat, orderly rows.

 

Cristina Archer of the University of Delaware and colleagues report in Geophysical Research Letters that they started with a real, working offshore wind farm — Lillgrund in Sweden — and then, using computer simulations and real weather data, hypothetically arranged the turbines to achieve the optimum results.

 

The problem is a real one. In April two US scientists calculated that spacing set practical limits to wind power: the impact of air on turbine blades set them turning but also set up eddies that took the wind out of the sails of the turbine downstream.

 

Land costs are huge, so there is a limit to the possibilities of spacing for onshore wind farmers. But offshore farms can spread themselves a little more comfortably. Dr Archer and her colleagues tried six simulated configurations, sometimes keeping the turbines at the same distance, sometimes further apart, and sometimes staggering them according to the prevailing wind, in the way theatre seats are staggered to give everyone a better view of the stage.

 

It was a combination of the two approaches — more generous spacing, and a staggered alignment — that gave the best results. In general, they argue, the right placement and arrangement could improve energy yields by 13 to 33 per cent.

 

Last year, Dr Archer and a colleague from California calculated that wind turbines could deliver half the world's energy demands by 2030 with minimal environmental impact. This would require four million turbines set to catch the wind at 100 metres above ground level in all the windiest places.