Last week we have spoken about an Innovative Mechanism that Improves Off-Shore Wind Turbines’ Safety. Using an axle instead of a gearbox, the turbines will harvest more efficient the wind and will not break down in harsh weather conditions.
But it seems that developments in this area did not stop here. A Canadian based company has developed a small prototype wind turbine that uses friction instead of the conventional gearbox to transfer the wind power from the blades to the generator. CWind has also begun the work on a larger scale project of a two-megawatt wind turbine. The “friction drive” system proves to be very efficient, reliable and cheap in maintenance.
In standard wind turbines, the blades turn a drive shaft which engages the gearbox. The gearbox is the most vulnerable part, as in wind blasts it has to withstand very high mechanical stress. In time, it will wear down or break some metal teeth making it in short time unusable.
CWind comes with a completely new design in which the drive shaft is connected directly to a large metal flywheel that has eight smaller secondary shafts on the outside. Each of the eight shafts is connected to a 250-kilowatt generator and each is lined with several specially designed tires that grip the surface of the flywheel. When the flywheel spins, it engages the generators by turning the tire-lined shafts.
The complete system is controlled by software. In case of a wind blast when the flywheel suddenly speeds up, the tires will temporarily slip decreasing the impact on the generators. When the wind slows down, the secondary shafts can also be disengaged individually from the flywheel, reducing friction and allowing the still connected shafts to keep their generators operating at high capacity. When the wind increases again, the disengaged shafts will be connected adding friction and engaging idle generators.
“We’re using friction. It’s not mechanically hard-coupled. We can operate the generators at optimal speed all the time” said Na’al Nayef, a CWind engineer and co-inventor of the system.
The other most important thing of this new design is the fact that it comes with a efficiency increase of at least 5 percent over the standard wind turbines. The percentage was though calculated on the 65-kilowatt prototype only.