A New Prototype Doubles the Energy Harvested From Ocean Waves

Harnessing the untapped potential of ocean waves.
Brad Bergan
The new ocean wave energy device.RMIT University

A new challenger enters the renewable energy arena.

Researchers have designed a prototype technology capable of doubling the power harvested from ocean waves, in a development that could bring wave energy into the family of viably renewable sources of energy, according to a recent study published in the journal Applied Energy.

And it solves key challenges that previously stymied wave power development.

Doubling the efficiency of harvesting ocean waves

Ocean wave energy has tremendous untapped potential, with estimates placing the total power generated by coastal waves around the world each year on par with the annual global production of electricity. But the difficulty engineers face in developing new technological solutions capable of efficiently extracting this natural power of waves, while also surviving the wilds of the ocean environment has held back wave energy, stuck at the experimental phase.

But a new wave energy converter from a research team under the leadership of RMIT University can do it at twice the efficiency in harvesting power as comparable technologies developed so far, according to a press release. The new technology uses a dual-turbine design of a kind that has never been tried before. This is significant because wave energy is one of the most highly-anticipated sources of green, reliable energy. "While wind and solar dominate the renewable market, they are available only 20% to 30% of the time," said Lead Researcher Professor Xu Wang of RMIT University, in the press release.

News Schematic Design
A schematic of the crucial operational features of the novel wave power technology. Source: RMIT University

The new wave energy generator stays 'in-sync' with ocean motion

"Wave energy is available 90% of the time on average and the potential power contained in offshore waves is immense," added Wang. "Our prototype technology overcomes some of the key technical challenges that have been holding back the wave energy industry from large-scale development. With further development, we hope this technology could be the foundation for a thriving new renewable energy industry delivering massive environmental and economic benefits." Among the experimental methods to harvest wave energy is a buoy-like converter, called a "point absorber", which works great in offshore environments. These "point absorbers" harvest energy as the ocean's surface moves up and down, and its manufacture and installation processes are typically cost-effective. But it's a highly sensitive device, requiring ultra-precise synchronization with incoming wave movement to optimize the efficiency of energy harvesting. This generally calls for an array of sensors, control processors, and actuators, which slaps a substantial layer of complexity into the proposition. And if you know anything about engineering, you also know high complexity means high risk of underperformance, or even failure, along with heavy maintenance and reliability needs.

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However, the new prototype doesn't need extravagant synching technology because it floats up and down with wave swells naturally. "By always staying in sync with the movement of the waves, we can maximize the energy that's harvested," said Wang. "Combined with our unique counter-rotating dual turbine wheels, this prototype can double the output power harvested from ocean waves, compared with other experimental point absorber technologies." Additional researchers from Beihang University, China, also contributed to the new wave harvesting device. The power generator itself is positioned above the waterline of the buoy, so corrosive seawater is kept separate, significantly extending the lifespan of the device. It's still years from rolling out at scales comparable to solar or wind energy, but the availability and sheer power potential of wave power could soon assist carbon-neutral desalination plants, providing fresh water for the agriculture industry, in addition to conventional electrical grids.

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