Almost every device that converts wave power into electricity uses a turbine of some sort. Oscilla Power Inc. (OPI) has a unique spin - or lack of spin, actually - on wave power: a wave energy harvester with no moving parts.
Taking advantage of the Villari effect (also called reverse magnetostriction) OPI’s patent-pending device employs a coil of wire wrapped around a magnetic core. Sound like a turbine? Here’s the twist: instead of spinning the magnet near the coil to induce a current, the waves cause minor tension on the core, producing imperceptible changes - less than 200 parts-per-million - in its dimensions. The fluctuating tension alters the magnetic field, and a changing magnetic field around a coil of wire will induce a current in the coil. A lab model of their generator is shown here:
Image: Oscilla Power, Inc.
In the picture below, the four vertical rods connect the buoy to an undersea plate. The rods also serve as the generators, and the tethers carry the current to the grid on shore. The same principle can be used off-grid to power oceanographic buoys.
Image: Oscilla Power, Inc.
The lack of moving parts translates to increased simplicity and reliability along with decreased cost and maintenance. The generator is made from relatively inexpensive and readily available materials such as aluminum, iron, copper, and steel. Although small rare earth magnets are used in the model, Oscilla believes that they can be replaced by ferrite magnets if necessary. That would require larger rods for the same electricity production, since ferrite magnets aren’t as strong as rare earth magnets. No worries though, OPI says that its generator scales up nicely.
OPI, in conjunction with University of New Hampshire’s Center for Ocean Renewable Energy, has tested a one-fourth scale prototype off the coast of New Hampshire. The unit performed as designed, delivering power across a wide range of wave frequencies. They plan a full-scale test in the summer of 2014. Although they won’t say exactly how much energy the device generates, OPI claims that electricity can be generated at a cost of less than $0.10/kWh (unsubsidized), which compares quite favorably to other forms of wave power harvesting.
The next time you hear someone say they’re amped up to catch a wave, it may not be a surfer - it could be an engineer in a lab coat, developing new ways to generate electricity. Hang ten, dude!