The innovative turbines, apart from harvesting wave energy, could also protect the coastline from erosion
Right now, Japan imports 84% of its energy, but all over the country scientists are busy innovating with the goal of changing this. Professor Tsumoru Shintake, at the Okinawa Institute of Science and Technology Graduate University (OIST), is one of them. Originally from the high-energy accelerator field, in 2012 he decided to seek new energy resources, so he worked on a new design of submerged marine turbines to harness the energy of the Kuroshio Current that flows from the eastern coast of Taiwan and around the southern parts of Japan. Professor Shintake estimates that if just 1% of the Japanese coastline were fitted with these turbines, they would generate around 10 GW of electricity, roughly equal to the power of 10 nuclear reactors. In addition to power generation, the newly-designed turbines could also help protect the coasts from erosion while being affordable for those regions with limited funding and infrastructure.
The innovative design
The turbines are designed to be anchored to the sea floor with mooring cables near tetrapods used in breakwaters or natural barriers such as coral reefs, having enormous potential to dampen the impact of powerful waves on shorelines and capture the ocean’s endless kinetic energy. Inspired by the movement of a dolphin’s fin, the turbines’ blades are flexible and thus able to release stress, a characteristic that makes them suitable for places prone to storms and typhoons. Their supporting structure is also flexible, “like a flower,” Professor Shintake explains, so the whole structure bends back along its anchoring axe against the wind. For those worrying about marine life, the new turbines are built taking this factor into consideration and the flexible blades rotate at a carefully calculated speed that allows creatures caught among them to escape.
Each turbine would feature five dark-colored blades with a diameter of 70 cm (27.6 in) attached to a permanent magnet electric generator encased in ceramic to keep the corroding seawater out. The electrical energy created would be channeled through a cable in the white-colored support stem and back to shore to feed into the grid. The turbines are estimated to last for ten years before needing to be replaced, while their maintenance can be undertaken by the same crews who inspect tetrapods.
The turbines’ ideal placing
One prime location to place turbines is in front of tetrapods at the shoreline. At this location, the turbines transform the energy from incoming waves into usable electricity—this in turn dissipates wave strength and protects the shoreline.
Coral reefs are another type of location with strong breaking waves. Water moving from the deep sea over a shallow reef creates fast jet flows of water. Arrays of small Wave Energy Converter (WECs) will harness electricity from the vortex flow of breaking waves.
Undergoing testing
In 2013, the OIST researchers launched The Wave Energy Converter (WEC) project, which involves placing turbines at key locations near the shoreline to generate energy. Now, half-scale models (0.35-meter diameter turbines) are about to be installed for their first commercial experiment. The project includes installing two WEC turbines that will power LEDs for a demonstration.
Source: Okinawa Institute of Science and Technology News Center
The blade design and materials are inspired by dolphin fins
Photo source: CNN
After creating a prototype turbine, its design was being tested from a boat.
Photo source: CNN
After creating a prototype turbine, its design was being tested from a boat.
Photo source: CNN
Photo credits: OIST
