Observations of schooling fish and the suggestion that there is constructive hydrodynamic interference between the wakes of neighboring fish has given an associate professor of aeronautics and bioengineering at Caltech an idea about how to more efficiently field wind turbines. "It turns out that many of the same physical principles can be applied to the interaction of vertical-axis wind turbines," says fluid-dynamics expert John Dabiri.
The biggest challenge with current wind farms is lack of space. Conventional horizontal-axis wind turbines 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.
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 which has been replicated in simulations—was that the vortices formed a "staircase" pattern, which contrasts with current wind farms that place turbines neatly in rows.
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. Once they've identified the optimal placement, Dabiri believes it may be possible to produce more than 10 times the amount of energy currently provided by a farm of horizontal turbines. The results are sufficiently compelling that the Caltech group is pursuing a field demonstration of the idea.
Dabiri has purchased two acres of land north of Los Angeles, where he is establishing the Caltech Field Laboratory for Optimized Wind Energy (FLOWE). The pilot program at the site will feature six vertical turbines on mobile platforms.
Dabiri and his team will systematically move the turbines around, testing various configurations to find the most efficient patterns.
The initial phase of the study will attempt to demonstrate which configuration of units will improve power output and performance relative to a horizontal-axis wind turbine farm with a similar sized plot of land.
More information is available at the Caltech site: http://dabiri.caltech.edu/research/wind-energy.html
