Clipper Windpower (Clipper) currently has the distinction of building the world’s largest wind energy project. The wind turbine maker, headquartered in both London and Carpinteria, California, has entered into a joint venture with BP Alternative Energy to build a 5,050 megawatt facility in South Dakota.
The facility will use Clipper’s Liberty wind turbine, which has patent protection from all angles. According to Clipper’s “at a glance” page, the Liberty includes patented generators, a patented distributed powertrain and patented variable speed technology.
Some of the patents that cover the Liberty include U.S. Patent Nos. 7,233,129 and 7,339,355 (generators), U.S. Patent Nos. 6,653,744, 6,731,017 and 7,069,802 (distributed powertrain), and U.S. Patent No. 7,042,110 (variable speed technology). The patented innovations make the Liberty more efficient and more reliable than traditional large scale wind turbine designs.
The fundamental components of a wind turbine are the rotor, gearbox and generator. The gearbox converts low speed rotation from the turbine blades into high speed rotation suitable for generating energy. The gearbox output shaft turns the shaft of the generator, which, through conversion circuits, connects to the utility grid to provide current to the grid.
Typical turbine gearboxes are “planetary” gearboxes (i.e., having outer gears revolving around a central “sun” gear) with the speed change occurring in three or four stages of rpm step-up. But planetary gearboxes for multi-megawatt turbines require huge, expensive gears and bearings as well as large generators. The parts are very heavy and need a lot of maintenance, and repairs can take a wind turbine off-line for a long period of time.
Clipper’s distributed powertrain patents generally relate to a compact gearbox with a multiple-path design to divide and distribute torque load. The load drives four smaller generators instead of a single big one.
Instead of a planetary gear arrangement, the patented design has helical gears to promote smooth meshing. The gear sets are in “cartridge” form and can be easily replaced without removing the gearbox.
Clipper’s variable speed technology uses magnet generators that improve efficiency. Traditional variable speed systems use generators which pull current from the turbine unit or the utility grid to excite the rotor and create a magnetic field.
The patented magnet generators don’t have to pull power from the unit or the grid because they are already magnetized. As a result, the Liberty can operate at higher efficiency over a wide range of loads.
The Clipper Liberty wind turbine is a great example of establishing robust patent protection by breaking down new technology into its patentable constituent parts and patenting as many of those parts as possible.