The Planet

There’s An Ocean Of Energy In The Sea. And This Team Just Unlocked It.

by James Poulos

December 18, 2017
An Okinawan wave breaker prepares to make waves. Photo by Banzai Hiroaki/Flickr.

Earth. Wind. Fire. Coming in the form of fossil fuels, stiff breezes, and solar power, alternative energy has always looked to the most fundamental of natural forces.

But if you’ve ever felt like a big one is missing from the list, you’d be right. Until now.

Hydroelectric power is nothing new, of course. (It’s also the source of international disputes and dangers.) But for the first time, the biggest source of water energy on Earth is open for business — the ocean. And this new method is as safe for the environment as it is for humans.

After four years of testing, Japanese researchers at the Okinawa Institute of Science and Technology have announced that their creation, a new type of underwater turbine system called the Sea Horse, is ready for market.

In a country still dealing with the aftermath of the Fukushima nuclear reactor disaster, this is big news. The institute’s professor Tsumoru Shintake says the combined productive power of 10 nuclear plants, 10 gigawatts, can be produced using the turbines along just 1% of the Japanese coastline. “The energy density of waves,” he notes, “is 100 times greater than that of wind.”

Shintake’s turbines would fit right in anywhere along the 30% of seashore currently dotted with tetrapods, submerged concrete pyramids placed to prevent erosion. His team designed the system to work in concert with the wave-breakers, drawing energy from the ripples as they slow them down. After all, it’s where waves break hardest that coastlines are most endangered — and where the ocean’s force is at its most concentrated and accessible.

None of that would matter much, however, if the underwater system couldn’t hit a crucial criterion. The turbine fans must be strong enough not to break apart and pollute the ocean, but they have to be gentle enough not to harm sea life.

Shintake and company found the solution by looking to nature itself for inspiration. “The blade design and materials are inspired by dolphin fins,” they explain. Like the turbines’ supporting legs, which they compare to flower stems, the blades are “flexible and, thus, able to release stress rather than remain rigid and risk breakage.” Rotating “at a carefully calculated speed,” they ensure any creatures passing through can escape unharmed.

The technology behind the fans incorporates more than thrifty, sturdy, and bendy materials. Key to the whole assembly is a special magnet mechanism that blocks seawater from entering the turbine’s shaft and keeps it turning usefully amid the irregular churn of the surf. Not a bad metaphor for the human condition.

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There’s An Ocean Of Energy In The Sea. And This Team Just Unlocked It.