Magazine

More

Pros and cons of vertical-axis wind turbines

Traditional vertical-axis wind turbines (VAWTs) generate power using a main rotor shaft that is positioned vertically.



This orientation allows generators and gearboxes to be placed close to the ground, creating a lower centre of gravity and more stability, and "omnidirectionality" - VAWTs do not need to face the wind. Savonius turbines are drag-type devices made of two or three staggered scoops that have less drag when moving against the wind than with it. Darrieus turbines look like an upside down egg-beater. They featureaerofoils arranged symmetrically in line with the shaft so that the rotor will turn no matter which way the wind is heading.

The shortcomings of the older versions of these concepts stem from "pulsatory torque", whichcauses damaging bending of the rotor blades. VAWTs also tend put undue strain on the bearings.