Researchers at the Okinawa Institute of Science and Technology in Japan are working on creating special turbines that generate wave energy while protecting shorelines from destruction. The turbines are designed to be anchored to the seabed by mooring ropes near the tetrapods (star-shaped concrete structures designed to reduce the destruction of the shore) or to natural barriers such as coral reefs.
These structures have a huge potential: they allow to weaken the influence of strong waves on the shoreline and absorb endless ocean energy.
For this project no special infrastructure is required, since wave turbines are attached to the strong elements of the shoreline.
"Surprisingly, 30% of the coast in the mainland Japan is covered with tetrapods and breakwaters," said Professor Tsumoru Shintake, the lead researcher of the project. "Using only 1% of the coast of mainland Japan, it is possible to generate about 10 gigawatts of energy, which is equivalent to the energy of 10 nuclear power plants. This is a huge unused capacity."
Each turbine has rotating blades attached to an electric generator on permanent magnets protected by a ceramic layer to prevent the ingress of seawater. The energy absorbed from the ground swell is transmitted through the cable down the structure and back to the shore for use in the grid.
Turbines are designed with security considerations.
To avoid harming wildlife, the speed of the blades is adjusted so that any animal caught in them will not be harmed.
The blades of the wave turbine are similarin flexibility to the fins of the dolphin.
This is done in order to avoid cracks under strong storms or because of swelling. The support structure is also flexible.
The estimated duration of the turbines is ten years before it has to be replaced, but its creators are thinking about the distant future.
“I’m imagining the planet two hundred years later,” said Shintake. “I hope these [turbines] will be working hard quietly, and nicely, on each beach on which they have been installed.”