The CVT (continuously variable transmission) technology is already being used in hybrid cars, and now it enters the wind turbine industry. Texas-based Viryd Technologies, use CVTs to make the fluctuating wind speeds convert into a more efficient stream of AC current that will be fed to the grids. Currently, complicated and expensive electronics is used to regulate power in wind turbines. The introduction of CVT could cut the cost of wind power generation of any wind turbine.
Viryd’s parent company is Fallbrook Technologies, who has already commercialized smooth-shifting alternative to gears and derailleurs in high-end bicycles, and is also developing larger vehicle applications.
CVTs vary transmission ratios by sliding metal belts up and down a set of precision curved parts – a design that is expensive to implement at high torque. Fallbrook’s technology relies on comparatively simple parts, promising lower cost and greater durability, according to CTO Rob Smithson. “It’s basically a big ball bearing, which is a global commodity,” Smithson says.
The main issue with building the CVT-based wind turbines is that they will have blades 15 times the size of their tested concept, and half-a-meter balls (compared to the initial CVT’s balls, who are slightly smaller than a golf ball). The torques required at such dimensions are huge, as Jason Cotrell, senior engineer at DOE’s National Wind Technology Center in Golden, CO, says: “Wind turbines are subject to very high torque for 80,000 hours of operation, so it’s a very challenging environment,” Cotrell says. “CVTs tend to be complex, and we haven’t yet verified that they’re suitably robust.” Their currently-built turbines can only generate about 8kW of power.
The $8 million project, led by Illinois Institute of Technology’s Wanger Institute for Sustainable Energy Research, is one of several to test whether the cheaper turbines can endure. If these prototypes pass muster, Viryd CEO John Langdon’s plan is to install 50 more during the first half of next year for dealers and then to begin marketing the turbine to homeowners and small businesses in the second half of the year. The turbine is rated to generate about 10,000 kilowatt-hours of electricity annually, which is close to the average U.S. homeowner’s power budget. Langdon predicts a ready market, thanks to state and federal incentives.
I can only imagine the noise those ball bearings will make with running, but, like it was with the Prius, it seems CVTs are a good idea when you want to un-complicate things and still keep them working.