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Capturing the Motion of the Ocean: Wave Energy Explained

July 6, 2015 - 11:44am


Energy Department-supported "Azura" wave energy converter is installed at a U.S. Navy test site in Hawaii. | Photo courtesy of Northwest Energy Innovations.

Energy Department-supported "Azura" wave energy converter is installed at a U.S. Navy test site in Hawaii. | Photo courtesy of Northwest Energy Innovations.

We live on a water planet. Roughly 71 percent of the Earth is covered in the stuff, and it’s constantly in motion -- tides surging rhythmically; powerful currents coursing beneath the surface; waves rolling across oceans and crashing against continents.

All that motion produces mind-boggling quantities of kinetic energy, just a stone’s throw from some of the nation’s most populated areas. With more than 50 percent of the population living within 50 miles of coastlines, there is vast potential to provide clean, renewable electricity to communities and cities across the United States.

So why haven’t we tapped into this plentiful, carbon-free power source lapping at our shores?

As it turns out, harnessing the might of the sea is harder than it sounds. Here’s how new technologies, including a revolutionary Energy Department-supported project, could soon change that. 

The Unforgiving Sea

Schooner Gulch State Beach, CA
Photo by Matt McIntosh/NOAA National Marine Sanctuaries.

“The sea was angry that day, my friends -- like an old man trying to send back soup in a deli.” George Costanza, Seinfeld

The ocean is a vast reservoir of kinetic energy, but it’s also a challenging place to generate electricity.

For starters, it’s important to be careful when combining electricity and water. On top of that, salt water can corrode metal components. Barnacles and other sea creatures can cling to exposed surfaces, blocking intakes and weighing down machinery. Storms and forceful waves can damage power systems or loosen them from their moorings.

There are also logistical issues, like finding a spot with strong waves or currents (but not too strong), connecting to the grid via an undersea cable, and avoiding conflicts with shipping lanes, fishing grounds, military exercises or any of the myriad other ways we use our bustling coastal waters.

These are real challenges -- but that’s why we’re working hard to find solutions. The Energy Department funds a wide range of projects aimed at improving the performance and durability of wave energy devices, including developing industry standards for components like cables, seals and electronics. We’re also conducting research that will help developers identify suitable locations for ocean energy projects.

Crunching the Numbers

Azura floats ready to launch
Photo courtesy of Northwest Energy Innovations.

Of all the obstacles facing wave energy today, the biggest isn’t monster waves or encrusting crustaceans -- it's cost.

Wind and solar have grabbed most of the renewable energy headlines in recent years because they’ve gotten dramatically cheaper in that time. But that didn’t happen overnight. Decades of research, testing and investment -- much of it supported by Energy Department initiatives -- have given us more reliable, cost-effective hardware, encouraging more installations and driving down energy prices.

The same needs to happen for wave power. Its proponents in the U.S. are still seeking the best way possible to generate electricity from the sea on a scale that makes economic sense. Solving that problem would be a massive step toward realizing this clean energy resource’s potential.

That’s what makes the Energy Department’s latest wave energy test collaboration in Hawaii so exciting.

Shake, Rattle and Roll

Azura wave energy converter prototype
Photo courtesy of Northwest Energy Innovations.

Last month, against the picturesque Hawaiian backdrop of Kaneohe Bay, Oregon-based Northwest Energy Innovations deployed a prototype of their “Azura” wave energy converter at the U.S. Navy’s Wave Energy Testing Site in Oahu.

Developed with funding support from the Energy Department, this 45-ton, bright yellow device stands out for reasons beyond its size and eye-catching color.

First, its design marks a radical shift in how wave energy devices operate. Waves have both side-to-side and up-and-down motion, but up to this point, almost all designs have been limited to one direction or the other. The Azura can harness movement in 360 degrees, bobbing, twisting and wobbling its way to a higher electricity output.

Second, the Azura is connected to Hawaii’s electric grid -- and it’s producing power. That may not sound revolutionary, but it’s actually the first device of its kind in the United States to reach that milestone and be verified by a third party (the University of Hawaii). Testing of the Azura will continue for a year, with potential for a full-scale demonstration in 2017.

The future of wave power will build on the success of projects like this. The Energy Department is committed to supporting the growth of this emerging technology with the hope that it will one day become an important source of clean energy for our nation, providing low-carbon electricity to some of the places where it’s needed most.