Abstract
Wave energy has the potential to meet nearly 10% of global electricity demand approximately 2,000 TWh/year). Unlike wind or solar energy, wave energy can be forecasted several days in advance and is located close to coastal areas with growing demand. Inventors and organizations around the world have tried to turn this low-frequency, low-amplitude resource into utility-scale electricity for decades. These attempts have universally used power generation technologies with moving parts, resulting in high operating and maintenance costs, as well as low efficiency and the need for large amounts of structural mass, which together drive up capital cost. The levelized cost of energy (LCOE) for wave energy has been estimated to be between 25 and 60 cents/kWh, many times higher than that from conventional sources.
At Oscilla Power, Inc. (OPI), we are developing a patented magnetostrictive wave energy harvester (MWEH) that could enable the disruptively low-cost production of grid-scale electricity from ocean waves. Designed to operate cost effectively across a wide range of wave conditions, the MWEH will be the first use of reverse magnetostriction, a phenomena in which high-magnitude, but low-displacement, mechanical load changes are converted into magnetic flux changes and then electricity (via induction), for large-scale energy production.
While the newly-developed, higher-performing magnetostrictive alloys (such as iron-gallium) are prohibitively expensive for utility-scale power generation applications, iron-aluminum (Fe-Al) alloys can provide the required cost and capacity.
Our iMEC technology platform enables Fe-Al alloys to provide the required performance for power generation. The driving magnetomotive force is provided by permanent magnets, which typically make up less than 1% of the generator mass.
Tension changes on this circuit result in changes in magnetic permeability of the Fe-Al rods, resulting in changes in flux density within the circuit—all with no perceptible relative motion (less than 200 ppm of deformation). Electricity is generated by electromagnetic induction, using copper coils wound around the alloy rods.
The pre-compressed rods never go out of compression during normal operation. During extreme conditions that result in very high tension, safety bolts are engaged that pick up the excess mechanical load. These features are intended to eliminate fatigue-related failures.
Magnetostrictive harvesters have been shown to have greater than 80% mechanical to electrical efficiency, a capability that should enable us to achieve higher efficiencies than have previously been demonstrated for wave energy converters (WEC).