Japan's tidal energy system makes a splash

In December 2010, Shinji Hiejima, associate professor of the Graduate School of Environmental and Life Science at Okayama University, Japan, developed a new type of tidal energy system, called the “Hydro-VENUS” or “Hydrokinetic-Vortex Energy Utilization System.” The Hydro-VENUS system will make energy available to coastal communities and communities with coastal neighbours who can potentially transfer the electricity to them. This energy will be environmentally friendly and there will be a constant supply since ocean currents are always moving.

According to Japan for Sustainability, the Hydro-VENUS system produces 75 per cent more energy than a propeller-based system. It is suggested as a replacement for a propeller type system for three reasons: the propeller system is made out of heavier materials which increase cost and decrease the amount of energy created, garbage and ocean debris can clog the propeller, and the propeller blades can harm marine life.

How Hydro-VENUS works 

The Hydro-VENUS works through a cylinder attached to a rod which is connected to a rotating shaft. The cylinder is held upright through buoyancy since it is hollow. As the ocean currents pass by the cylinder, a vortex is created at the back side of the cylinder, pulling and rotating the shaft. That rotational energy is transferred to a generator, creating electricity. When the cylinder is released from the currents, it becomes upright, returning to its original position, thus starting the cycle over.

The tidal system is different from a propeller-based system where the currents have to spin the propeller in order to create energy and requires a lot of force since the propeller is hard to turn. More energy can be created through the Hydro-VENUS system since less force is needed to move the cylinder pendulum.

Hiejima first started his research on the Hydro-VENUS because of his fascination with the structure of bridges and the wind’s effect on them. He states in an article by Okayama University, “ … Large bridges oscillate when hit by strong winds such as typhoons. Now, I am focusing on harnessing tidal energy as a stable source of electricity.”