The main challenge with wind energy is intermittency. This problem is solved with Energy Storage, however, while developing energy storage, NWG focused efforts on designing a drive train that could collect more energy from the wind, while providing greater efficiency and reliability.
NWG holds patent protection and internal documentation on a friction drive for wind turbines with rated powers between 65kW and 7.5MW.
Efficiency: In 2007, NWG replaced a gearbox driven wind turbine rated at 65kW with a similarly rated friction drive transmission. In 2008, the company used a real time data acquisition system to field test the friction drive wind turbine. After one full year of operation the power curve of the gearbox drive and the power curve of the friction drive were compared on the same footprint with same operating conditions. The friction drive collected 25% more energy.
Reliability: The transmission is designed to absorb any sudden wind gust while operating independent output shafts to connected multiple generators.
The first generator engages at 3m/s and operates at its maximum efficiency point. As the wind speed increases additional generators engage. If any of the output shafts or the generating component fails, the unit maintains operations at 95% efficiency until the repair or replacement can be made. All generating components can be replaced via an internal crane. Hoisting occurs on the inside of the tower. An external crane is only needed for the initial set up of the wind turbine.
NWG detailed a 2.0MW drive train with the help of McLaren Performance Engineering and have worked with Garrard Hassan, MPR Associate Engineers, Tipton Engineering and GEC to validate the wind turbine drive from 100kW to 7.5MW.
NWG has identified several markets for the wind turbine technology:
• Retrofitting failure prone gearbox drives for increased ROI for the wind farm owner
• Small scale in the fence power with 100kW wind turbine battery solution
• Night wind to provide charge for compressed air energy storage, batteries, and plug in for truck stops, battery operated vehicles
• Offshore and second grade wind sites