Schooling fish inspire new approach to wind farming
By Ben Coxworth
May 18, 2010
Schooling fish, it turns out, have a lot to teach us about setting up wind farms. That’s the conclusion reached by John Dabiri, a fluid dynamics expert from the California Institute of Technology (Caltech). One of the biggest current problems with wind farms is the large land area that they require - if you place the turbines too close to one another, they will be adversely effected by each other’s turbulence. By applying principles learned from observing fish, however, Dabiri thinks he might have found a solution.
First off, he is not using the common type of wind turbine. What we’re used to seeing are horizontal-axis turbines, with the big windmill-style blades that spin in a circle perpendicular to the ground. Dabiri is using vertical-axis turbines, that look not unlike an old-school lawnmower (or combine) reel standing on one end. Because they don’t have big blades sweeping circles in the air, they can be more densely-spaced than horizontal-axis machines.
One of the first things Dabiri noticed with schooling fish was that the vortices left behind individual fish sometimes rotated clockwise, and sometimes counter-clockwise. In traditional wind farms, all the turbines spin in the same direction, so they all generate the same direction of vortex. Based on this observation, he plans on alternating the spinning direction of neighboring turbines, to see if they actually benefit from the alternating vortices.
Dabiri also noticed that the fish and their vortices were arranged in a staircase pattern relative to one another. Again, this runs contrary to most wind farms, where the turbines are placed in neat rows. By conducting a field study incorporating closely-spaced, staggered vertical-axis turbines spinning in alternating directions, he hopes to show just how much more efficient wind power can become. According to Caltech's computer models, he believes his set up could be up to ten times more efficient than traditional models.
“Our goal is to demonstrate a new technology that enables us to extract significantly more wind energy from a given parcel of land than is currently possible using existing methods," said Dabiri. "We want to take advantage of constructive aerodynamic interference between closely spaced vertical-axis wind turbines. Our results can potentially make better use of existing wind farms, allow for wind farms to be located closer to urban centers - reducing power transmission costs - and reduce the size of offshore installations."