Japan has exclusive economic control over the 6th largest ocean area in the world, and what they think of as an enormous and untapped “blue energy” beneath the waves.
Research into converting tidal energy into electricity has a long history in Europe, but in Japan the pursuit was exponentially ramped up after the disastrous 2011 earthquake off the Pacific coast of Tōhoku. The resulting tsunami swept the Japanese mainland, killing over ten thousand people and fatally crippling the aging Fukushima Daiichi Nuclear Power Plant.
Tidal energy is estimated to have the potential equivalent of 20 nuclear power plants, especially in the Seto Inland Sea where there are so many viable currents that it could generate the power of 7 nuclear power plants on its own.
Additionally, there is a push towards local production of energy to increase the self-sufficiency rate of each region in Japan and create a disaster-resistant country by diversifying energy resources.
The propeller type turbine systems in Europe have three major drawbacks: they require costly high-strength materials, pollution chokes and damage the turbines, and fisherman and conservationists consider the sharp blades to be a hazard to marine life.
To resolve these challenges, researchers in Japan began by considering energy generated by the flow induced vibrations of cylinders placed horizontally in water. As waves move across them, the cylinders moves translationally with the current so that they can be effective with both incoming and outgoing tides. They have an energy yield efficiency of approximately 37%.
New research has focused on the concept for Hydro-VENUS, developed by Shinji Hiejima, Associate Professor of Environmental and Life Science at Okayama University. His cylinders with do not vibrate translationally but rotationally. Initial tests yield an impressive energy efficiency of 76%. Funding the cost of converting the test cylinders from 1.5 meters to the goal of 20 meters to conduct large scale observational testing is the next step.
The concept has been patented and the device has demonstrated potential, so it is a matter of only time before a sustainable tidal energy system in Japan will prevail over nuclear and fossil fuels.