Image: Ocean Power Technologies
Aerospace giant Lockheed Martin recently signed a contract to build the world’s largest wave energy farm, which will be located off the coast of Victoria, Australia. The 62.5 megawatt wave farm will consist of Ocean Power Technologies’ (OPT) PowerBuoy® wave energy converters.
The PowerBuoy is a piston style wave energy harvester. Most of it is below sea level, anchored to the ocean floor. A piston is connected to a floating island - the Take Off Unit - that bobs up and down with the waves. Those movements are converted to rotational motion that spins a generator. The 600 Volt outputs of several PowerBuoys are connected to an Underwater Substation Pod whose output goes to shore through a subsea cable.
Video: Ocean Power Technologies
The project will roll out in three phases, with the first phase producing 2.5 MW peak. It’s likely that they’ll use Mark 3 PowerBuoys, which have been thoroughly tested off the coasts of Hawaii and Scotland. Each Mark 3 weighs 180 tons and can be towed to its location by a standard tugboat. It has a peak output of 866 kW and a projected life of 25 years.
Under development is the Mark 4 PowerBuoy, with a peak output of 2.4 MW. As part of the agreement, Lockheed Martin will assist OPT with the design and manufacturing of its product line, so we’re likely to see the Mark 4 in later phases of this project.
Compared to offshore wind power, wave energy offers several advantages. First, the converters only stand 38 feet (11.5 m) above the ocean surface, so they’re barely visible from the shoreline. According to the US Department of Energy, “The size of the PowerBuoys when viewed from shore would be [equivalent to] approximately 1.6 millimeters when viewed from arm’s length.” They also produce less noise and have practically no impact on ocean life, including birds. Wave energy can be predicted up to 72 hours in advance, giving grid operators plenty of notice regarding changes in electricity production.
When completed, this 62.5 MW project will be the largest wave energy farm in the world. That record is likely to be short-lived, however, as OPT is proposing a 100 MW wave park off the coast of Oregon.