turbulent ocean
Julie Hambleton
Julie Hambleton
May 29, 2024 ·  4 min read

Japan is Dropping a Gargantuan Turbine into the Ocean to Harness ‘Limitless’ Energy

Imagine if we could harness the movements of the ocean’s currents into an unlimited supply of energy for entire countries. In Japan, they no longer have to imagine it – they are attempting to make it a reality. They are soon going to be placing a massive turbine into the ocean that they say will harness limitless energy. This is how it will work.

Japan is Dropping a Giant Turbine into the Ocean to Harness Limitless, Sustainable Energy

The ocean’s waters are in constant motion. Even in its depths, the water is not sitting still. There is a current that continuously flows in one direction or another. These currents are no gentle push of water, either – they are strong. Harnessing their power could mean a sustainable, limitless source of energy. This is what Japan is attempting to do in order to power their entire country. They are going to put a gigantic turbine at the bottom of the ocean to harness the limitless power of the ocean’s currents. (1)

Of course, in order to harness the power of the ocean’s currents, the turbine first must be able to withstand them. They are very powerful, after all. Ishikawajima-Harima Heavy Industries, or IHI Corporation, for short, has figured out that if the turbine is big and heavy enough, it can. (2)

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A Milestone Complete

In 2017, IHI Corporation partnered with New Energy and Industrial Technology Development Organization (NEDO) to see if their turbine designs could actually be successful in a real-world setting. They placed a smaller, prototype version of the gigantic turbine in the ocean off of Japan’s southwestern coast. This past February the smaller turbine successfully completed a three-and-a-half-year field test, proving that their idea and their design could actually work long-term.

Kairyu Diagram

The prototype is called Kairyu, which means “ocean current” in Japanese. Calling it the smaller version of the real turbine proves just how gigantic this structure will be. Kairyu consists of a 66-foot fuselage between a pair of cylinders that are similar in size. Each cylinder has a power generation system that is attached to 36-foot turbine blades.

The researchers then tether the turbine to the ocean floor by an anchor line and power cables. From there, floating underneath the ocean’s surface, the turbine can orient itself to follow the ebbs and flows of the ocean’s current. This means that it can position itself appropriately to make the best of use of the deep ocean’s changing currents to generate the most power possible. The turbine then channels that power into a grid.

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Why Is This So Important for Japan?

Japan is a small island nation that currently relies on imported fossil fuels for nearly all of its electricity. Having suffered greatly from the 2011 Fukushima nuclear disaster, public sentiment toward using nuclear energy for power has decreased substantially. Wind turbines are also not a viable option because of the country’s mountainous terrain. Finally, their location, being quite far away from most other nations, makes energy trade a non-option, as well. For these reasons, they have a high amount of motivation to figure out other ways to power their country. 

The Kuroshio Current

What Japan lacks in viable terrain for other forms of renewable energy, it more than makes up for in long stretches of coast and uninterrupted ocean. The currents off of the Japanese coast are also particularly strong because of something called the Kuroshio current. To say this current is powerful would be an understatement. IHI estimates that harnessing the power of Kuroshio could generate around 205 gigawatts of electricity per year. They say that this is roughly the same amount as Japan’s current yearly power generation.

Of course, ocean waters can be rough, especially near the surface where any kind of power generation system can easily and quickly be destroyed in a typhoon. This is why the prototype was designed to sit 164 feet below the surface, rather than floating on or near the top.

As it floats towards the water’s surface, it creates a drag that makes the turbines spin. As the blades rotate in opposite directions they keep the turbine stable. With a flow of one to two meters of water per second, Kairyu was capable of pumping out 100 kilowatts of power. That may not seem like much, but it proved that if a smaller version of the underwater turbine is possible to withstand what the ocean throws at it, then a gigantic version will fare even better. On top of that, it will have an immense amount of power output. This means we could see an underwater power generator farm off the coast of Japan within the next decade – if the researchers can indeed successfully scale-up Kairyu. If this does happen, this could mean a country powered entirely by the sustainable, reliable power of its ocean currents. 

Keep Reading: Huge Wind Turbine With 350-Foot Blades Can Power A Home For Two Days With One Turn


  1. Japan Is Dropping a Gargantuan Turbine Into The Ocean to Harness ‘Limitless’ Energy.” Science Alert. Mike McRae. June 10, 2022.
  2. “IHI Demonstrated the World’s Largest Ocean Current Turbine for the First Time in the World” IHI. 2019