The Vertical-Axis Turbine

Wind-turbine designs can be classified as either vertical axis or horizontal axis, referring to the axis about which the rotor spins. Most turbines seen in use are horizontal axis, as that style is more efficient than vertical axis turbines. This difference in efficiency is largely a matter of aerodynamics—horizontal-axis turbines’ blades take full advantage of aerodynamic lift. Vertical-axis turbines are easier to build, though, offering some advantages in their simpler design. For example, vertical-axis turbines need no consideration of pointing into the wind, as they use wind from any direction to spin.