Japan designs WEC turbine to tame shoreline waves

OIST turbines placed in an array (Image: OIST)

Researchers from the Okinawa Institute of Science and Technology Graduate University (OIST) have outlined plans for a wave energy turbine that could provide protection for the shore while also generating power from the waves.

The project being developed by OIST team involves placing turbines at key locations near the shoreline, such as nearby tetrapods or among coral reefs, to generate energy.

Each location allows the turbines to be exposed to ideal wave conditions that allow them not only to generate clean and renewable energy, but also to help protect the coasts from erosion while being affordable for those with limited funding and infrastructure, OIST said.

The turbines themselves are built to withstand the forces thrust upon them during harsh wave conditions as well as extreme weather, such as typhoons, according to OIST.

Five-blade turbine design by OIST (Image: OIST)

The blade design and materials are inspired by dolphin fins – they are flexible, and thus able to release stress rather than remain rigid and risk breakage, OIST informed.

The five-blade turbine has a diameter of about 0.7 meters. Its blades rotate on their axis when influenced by ocean wave.

The axis is attached to a permanent magnet electric generator that transforms the ocean wave energy into usable electricity. The ceramic mechanical seal protects the electrical components inside of the body from any saltwater leakage.

OIST said the turbine has been designed to function for ten years before it needs replacing.

The supporting structure for the turbines is also flexible and the turbines bend along their anchoring axes, according to Tsumoru Shintake, Professor at OIST.

The turbines are also said to be built to be safe for surrounding marine life as their blades rotate at a carefully calculated speed that allows creatures caught among them to escape.

One prime location to place turbines is in front of tetrapods at the shoreline. Tetrapods are concrete structures shaped somewhat like pyramids that are often placed along a coastline to weaken the force of incoming waves and protect the shore from erosion.

At this location, the turbines transform the energy from incoming waves into usable electricity which in turn dissipates wave strength and protects the shoreline.

OIST team (Photo: OIST)

Coral reefs are another type of location with strong breaking waves. Arrays of small WECs could harness electricity from the vortex flow of breaking waves, OIST suggests.

Replacing regular with ‘intelligent’ tetrapods and wave breakers, with turbines attached to or near them, would both generate energy as well as help to protect the coasts, Shintake said.

The next step for Shintake and his team is to install the half-scale models of the turbine, with 0.35-meter diameter, for their first commercial experiment.

The team will soon install two wave energy conversion (WEC) turbines in order to power LEDs for a demonstration.