Saturday, May 28, 2022

New wave energy converter extracts twice the power from ocean waves

The untapped potential for ocean wave energy is vast – it has been estimated that the power from coastal waves around the world each year is equivalent to the annual global electricity production. The idea of capturing energy from ocean waves has been around for centuries. But the challenges of developing technologies that can effectively extract that natural power and withstand the harsh marine environment have kept wave energy stuck at the experimental stage.

Now, researchers at Australia’s RMIT have developed a wave energy converter that they say is twice as efficient at harvesting energy as any similar technology developed to date. The team hopes the novel design could open the door to finally make wave energy a viable renewable alternative.

The prototype employs a “world-first, dual-turbine design,” which overcomes some of the key technical challenges that have been holding back the wave energy industry from large-scale deployment.

The prototype dual-turbine wave energy conversion technology.
The prototype dual-turbine wave energy conversion technology. Credit: RMIT

One of the most popular experimental approaches is to harvest wave energy through a buoy-type converter known as a “point absorber,” which consists of a flotation device on the surface that is tethered to the seabed. It harvests energy from the up and down movement of waves, but the technology is generally cost-effective to manufacture and install.

To efficiently harvest energy from the ocean, point absorber buoys typically need an array of sensors, actuators, and control processors. This adds complexity to the system that can cause underperformance, as well as reliability and maintenance issues.

The RMIT-created prototype needs no special synching tech, as the device naturally floats up and down with the swell of the wave. Two turbine wheels that are stacked on top of each other rotate in opposite directions and are connected to a generator through shafts and a belt-pulley-driven transmission system. The generator is housed inside a buoy above the waterline to protect it from corrosion and extend the lifespan of the device.

Schematic showing the key operational features of the prototype technology.
Schematic showing the key operational features of the prototype technology. Credit: RMIT

By always staying in sync with the movement of the waves, we can maximize the energy that’s harvested,” lead researcher Professor Xu Wang said. “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.”

The prototype has been successfully tested at a lab scale. The results showed that the device could double the power harvested from ocean waves while promising a simpler and cost-effective path forward. The research team is keen to collaborate with industry partners to test a full-scale model and work towards commercial viability.

With further development, we hope this technology could be the foundation for a thriving new renewable energy industry delivering massive environmental and economic benefits,” Wang said.

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