Wind Farms Of Small Vertical Axis Turbines More Efficient, Cheaper Than Conventional Projects
photo: John Dabiri/Caltech
An interesting new study in the Journal of Renewable and Sustainable Energy turns on its head conventional wisdom about both the optimum technical solution and spacing for wind power projects so that they generate the most electricity.Researchers from the California Institute of Technology found that large horizontal axis wind turbines, broadly spaced (as in what you likely think of in a commercial wind farm) are far bettered by using shorter, vertical axis turbines, tightly spaced.
VAWTs are ideal, [John] Dabiri says, because they can be positioned very close to one another. This lets them capture nearly all of the energy of the blowing wind and even wind energy above the farm. Having every turbine turn in the opposite direction of its neighbors, the researchers found, also increases their efficiency, perhaps because the opposing spins decrease the drag on each turbine, allowing it to spin faster (Dabiri got the idea for using this type of constructive interference from his studies of schooling fish). (Eureka Alerts)
In tests, VAWTs generate 21-47 watts of power be square meter of land area of the project, compared 2-3 watts for the HAWTs.
As for the notion that you need to put up wind turbines at a greater height to capture the increased wind speeds, Dabiri notes that wind speeds at lower altitudes are sufficient to supply several times the world's electricity demand.
What's more, the VAWTs are less expensive to build, and perhaps most importantly consider the opposition to commercial-scale wind power projects by neighbors upset that their view will be spoiled.