Horizontal-axis windmills, with their traditional daisy design, are more efficient than their vertical counterparts, which resemble the beaters of an electric mixer.
But one company is hoping the two styles will complement each other.
Wind Harvest International aims to plant their vertical-axis windmills in groups of three among horizontal turbines to possibly double the farm's energy yield.
Vertical windmills are better for capturing the gusty winds that are closer to the ground. Overall however, a single vertical turbine lacks efficiency. Some of its blades are always positioned against the wind, which results in drag.
But placing three of them right next to each other—with their blades turning in alternate directions—creates a vortex. The small tornado generated between the turbines raises wind speed. Rotors on both side quicken, torque increases, and energy output grows.
Greentech Media reports:
Boosting the performance of existing turbines would further help ameliorate wind's chronic problem: unpredictability, resulting in wind turbines that only generate power about 30 percent of the time. By increasing the power output when the wind blows, the capacity factor could creep up. Reliability could also potentially increase: in high wind conditions, wind farm owners could shut off their horizontal turbines but still harvest power from the vertical ones.
Whether the vertical trios might even bring higher winds to the larger horizontal turbines remains to be seen. But the squat, cyclone-spinning windmills could also aid the wind industry's real estate concerns. After huge investments in infrastructure (roads, zoning, fencing), the farms could boost their windmill holding capacity.
Commercial production for the turbines is slated for 2011.