The quest to derive energy from wind may soon be getting some help from California Institute of Technology (Caltech) fluid-dynamics expert John Dabiri — and a school of fish.
“I became inspired by observations of schooling fish, and the suggestion that there is constructive hydrodynamic interference between the wakes of neighbouring fish,” says Dabiri "It turns out that many of the same physical principles can be applied to the interaction of vertical-axis wind turbines."
The biggest challenge with current wind farms is lack of space. The horizontal-axis wind turbines most commonly seen—those with large propellers—require a substantial amount of land to perform properly. “Propeller-style wind turbines suffer in performance as they come in proximity to one another,” says Dabiri.
Vertical turbineshave no propellers; instead, they use a vertical rotor. Because of this, the devices can be placed on smaller plots of land in a denser pattern. Caltech graduate students Robert Whittlesey and Sebastian Liska researched the use of vertical-axis turbines on small plots. Their results suggest that there may be substantial benefits to placing vertical-axis turbines in a strategic array, and that some configurations may allow the turbines to work more efficiently as a result of their relationship to others around them—a concept first triggered by examining schools of fish, according to a Caltech press release.
In current wind farms, all of the turbines rotate in the same direction. But while studying the vortices left behind by fish swimming in a school, Dabiri noticed that some vortices rotated clockwise, while others rotated counter-clockwise. Dabiri therefore wants to examine whether alternating the rotation of vertical-axis turbines in close proximity will help improve efficiency. The second observation he made studying fish—and seen in Whittlesey and Liska's simulation—was that the vortices formed a "staircase" pattern, which contrasts with current wind farms that place turbines neatly in rows.
Whittlesey and Liska's computer models predicted that the wind energy extracted from a parcel of land using this staggered placement approach would be several times that of conventional wind farms using horizontal-axis turbines. — Our Bureau