Our turbine is a 2-blade, horizontal axis design. The rotor orientation is downwind of the tower. It is a modern update of the pioneering Smith-Putnam wind turbine installed in 1941!
Two-blade downwind turbines are lighter weight and less expensive to manufacture relative to generating capability, and thus more economic, than 3-blade upwind turbines. The reasons are straightforward:
- Downwind rotor blades are driven away from the tower by the wind and do not have to resist bending to avoid hitting the tower.
- The blades on our turbines are attached to the rotor shaft via hinge pins. The largest source of fatigue loads on wind turbines occur at the blade root where blades are rigidly attached to the rotor hub. The hinged blade connection almost eliminates this source of fatigue loading.
- Downwind rotors automatically self-orient to changes in wind direction reducing fatigue loads while enhancing energy capture.
Significantly reducing fatigue loads leads to lower material requirements and lower cost.
The weight of the nacelle and rotor blades on top our turbine's tower, relative to its rotor swept-area, is approximately half that of 3-blade upwind turbines. This weight reduction is possible because of reduced influence of fatigue loads.
We estimate this weight reduction, relative to generating capability, will enable us to cut manufacturing costs by one-third. Passing this cost saving on to our customers will allow wind energy to be generated at competitive prices without subsidies.