Scientists erecting a VAWT at FLOWE

A group of CalTech researchers are looking to redesign our future wind farms by observing the way fish swim in schools.  Fluid dynamics expert, John Dabiri, recently purchased two acres of land north of Los Angeles, where he established the CalTech Field Laboratory for Optimized Wind Energy (FLOWE).  The project was inspired by the findings from a classroom research study conducted by graduate students, Robert Wittlesey and Sebastian Liska, supervised by Dabiri.  Their results suggest that there may be substantial benefits to placing vertical-axis wind turbines (VAWT) 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.

These results go against the industry norm as the most commonly used wind turbine in today’s market is the horizontal-axis wind turbine (HAWT).  Unlike the HAWT, the VAWT has no propellers and uses a vertical rotor to generate electricity.  Because of this design, these devices can be placed on smaller plots of land in a denser pattern.

So what do schools of fish have to do with the placement of wind turbines?

“[T]here is constructive hydrodynamic interference between the wakes of neighboring fish,” says Dabiri. “It turns out that many of the same physical principles can be applied to the interaction of vertical-axis wind turbines.”

When fish swim in schools, they align themselves strategically to optimize their forward propulsion, conserving maximum energy.  While studying the vortices left behind by these fish, Dabiri observed some that rotated clockwise, while others rotated counterclockwise.

These observations contrast with current wind farm designs, where turbines sit neatly in rows, all spinning the same way.  Dabiri, along with his team, are applying the patterns of these vortices to the placement of their wind turbines in hopes of obtaining maximum energy extraction.  Most often, VAWTS are smaller in size and used in residential settings.  The results of FLOWE could potentially change this limitation. As the technology becomes more advanced and is tested further, utility-scale applications could be on the horizon.  Once the team identifies 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.  However, as with any technology, we will to wait and see how it evolves.

VAWTs have been around for thousands of years, yet they still have not made a significant dent in the modern, commercial wind market.  Many industry experts, such as Ian Woofenden, believe VAWTs to be in many ways inferior to the traditional HAWT.  Their main inferiority, according to Woofenden, lies in company overhype of underperforming technologies, leading the consumer to believe that VAWTs are superior to HAWTs.

To salvage the VAWT’s reputation, AWEA created the Small Wind Certification Council (SWCC), an independent certification body that certifies small wind turbines to meet or exceed AWEA’s Small Wind Turbine Performance and Safety Standard.  The Council started accepting applications in February and many small wind companies, such as Windspire Energy, are eager to get certified.  Windspire Energy has provided three turbines for FLOWE.  In exchange, Dabiri will share his research results with the company.

Currently, FLOWE is in its initial phase, but Dabiri has big goals for the project.  He purposely chose to place the turbines in a real-world condition, as opposed to a computer generated model or a laboratory wind tunnel.  Dabiri feels that a field demonstration can easily facilitate a future expansion from a basic science project into a power-generating facility.  If the results of the pilot program are significantly favorable, Dabiri and his team hope to transition to power-generation experiments, where the power can be put to use either locally or via grid connection.  This could allow us to build wind farms closer to urban centers and power centers, reducing the cost of power transmission.