Fish schooling inspires new ideas for vertical-axis wind turbines

In the Los Angeles basin, the challenge of finding suitable space for large wind farms has prevented further progress in the use of wind energy. However, researcher John Dabiri, associate professor of aeronautics and bioengineering at California Institute of Technology (Caltech) and head of Caltech’s Biological Propulsion Laboratory, is using the bioinspiration from fish schooling in order to optimize the vertical-axis wind turbines.

“I became inspired by observations of schooling fish, and the suggestion that there is constructive hydrodynamic interference between the wakes of neighboring fish,” says John Dabiri,. “It turns out that many of the same physical principles can be applied to the interaction of vertical-axis wind turbines.”

Vertical turbines, which are relatively new additions to the wind-energy landscape, have no propellers. Instead, they use vertical rotors which 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 during a class research project supervised by Dabiri. Their results suggest that there may be substantial benefits to placing vertical-axis turbines in a strategic array.

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.

Once they do identify the optimal placement, the researchers believe it may be possible to produce more than 10 times the amount of energy currently provided by a farm of horizontal turbines.

Dabiri has purchased two acres of land north of Los Angeles, where he is establishing the Caltech Field Laboratory for Optimized Wind Energy (FLOWE) on which he tests various configurations in order to find more efficient patterns. The pilot program at the site currently features six vertical turbines which provide a total power capacity of 15 kW.

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. In the future, the researchers hope to achieve the transition to power-generation experiments in which the generated power can be put to use either locally or via a grid connection.