Scientists harnessing power from Hawaii’s waves

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MEGAN THOMPSON: The east coast of the Hawaiian island of Oahu is known for its breathtaking beaches and ocean vistas. But these beautiful waters aren’t just a draw for surfers and tourists. They are also a potential, untapped source of renewable energy – power generated from waves.

MEGAN THOMPSON: What’s the potential for wave energy?

PAT CROSS: It’s huge. The resource around the world is enormous.

MEGAN THOMPSON: Pat Cross is an oceanographer with a PhD in meteorology who manages the wave energy testing site off the Marine Corps Base Hawaii. Since launching two years ago, it’s been one of the few places in the world testing out different technologies to harness energy from waves.

PAT CROSS: The hard part is just how you capture it in a reliable and commercially viable way. The resource is huge, but the challenge is great– to capture it.

MEGAN THOMPSON: So far, no wave energy developers have figured that out, and that’s where this testing site comes in….it’s a joint venture by private business, the military, the department of energy, and the Hawaii Natural Energy Institute at the University of Hawaii, where Pat Cross works.

PAT CROSS: People are trying very different concepts about how best to capture the energy that’s packed into those waves. So one wave energy device looks very different from the next right now. And it remains to be seen kind of what the winners will be.

MEGAN THOMPSON: Wave energy is different from tidal energy, which harnesses power from the pull and push of tides with devices usually located underwater, and is already deployed in a handful of places around the world. The wave devices tested here sit mostly on top of the water. One looks different from the next, but they all use the movement of waves to turn a turbine, winch or hydraulic system to generate power. One device tested for a year and a half is called “The Azura.” It’s designed by a company called Azura Wave Energy based in Portland, Oregon. The steel device weighs about 45 tons and is the length of a flatbed truck. As the device rocks back and forth and up and down in the water, a float in the middle moves and rotates.

PAT CROSS: As it does that, it pushes hydraulics that runs a motor and makes electricity.

MEGAN THOMPSON: Last spring the Azura was lifted out of the water for cleaning and modification. After observing how it performed at the test site, researchers added a larger float to the middle to try to generate even more power.

PAT CROSS: So this is another wave energy conversion device….

MEGAN THOMPSON: Pat Cross showed us the second device tested so far, named the “Lifesaver,” because of its shape. It was developed by a Norwegian company called Fred Olsen.

PAT CROSS: You may have noticed that it looks nothing like the other wave energy converter that we saw. And it works in a very different way.

MEGAN THOMPSON: The device is connected to the ocean floor with 200-foot cables. Those cables are coiled around three winches – like pulleys – on the top of the device.

PAT CROSS: And so as the as the wave device rocks in the waves, those taut connections cause the winches to turn. So and you’re doing that in three points around the device.

MEGAN THOMPSON: The Lifesaver came to shore last spring at the Pearl Harbor Navy Base so researchers could make adjustments to the undersea cables and power connections. The U.S. Navy and the federal Department of Energy are funding the testing. Kail Macias is the technical director at The Naval Facilities Engineering and Expeditionary Warfare Center. He says the Department of Defense hopes wave energy might one day provide power to ships at sea or bases on remote islands.

KAIL MACIAS: It’s all about energy security. Really critical for us. When you look at the logistical constraints of what it takes to provide energy as far forward as possible for our Naval and D.O.D. forces, it does create quite a challenge. So when we buy, store, distribute fuel, it is a logistical constraint. So the nice thing about wave energy as it develops, diversifies our portfolio, and gives us another opportunity to provide another energy source.

MEGAN THOMPSON: Researchers plan to test at least eight more wave power devices in the coming years. The next one up is called an “oscillating water column” and works a bit differently than the others. Waves push and pull air through a chamber and then through a turbine, which spins and generates power. Researchers are also monitoring environmental impacts but so far have not found anything significant. The devices – as much as a mile offshore in Kaneohe Bay – are all connected to land by cables that come ashore here, and then feed into this old world war two bunker on the marine base that’s been converted into work space. It’s also where the wave devices connect to Oahu’s power grid.

MEGAN THOMPSON: This is the only wave energy testing site in the country connected to an electricity grid, and researchers say if they can get the devices to start generating a meaningful amount of electricity, it could be a more reliable source than wind or solar.

PAT CROSS: It can be quite consistent day and night, which of course solar is not. And– and it’s predictable fairly reliably out to the order of five days to a week. So you can kind of plan how much you’re gonna get from wave energy devices to feed into a power grid, for example.

MEGAN THOMPSON: George Hagerman, an ocean energy researcher at Virginia Tech, says beyond Hawaii, the entire Pacific coast of the U.S. has the most potential for wave power …and that it could one day supply electricity to millions of American homes. But, Hagerman cautions, that day is still a long way off.

GEORGE HAGERMAN: Wave power is popularly thought, and I think with some with some validity, to be at the stage where solar electric panels and land based wind turbines were in the late 1980s, early 90s. So maybe a decade or two in terms of really reaching the point where the technology is commercially widespread deployed.

MEGAN THOMPSON: Before that happens, researchers must figure out how these devices can toss about with the waves and survive harsh ocean conditions for prolonged periods of time. Until recently, Hagerman says, ocean-going devices have been designed with the exact opposite goal in mind.

GEORGE HAGERMAN: Historically, all of our mathematical modeling and understanding of the fluid dynamics of how. Waves interact with ocean structures is for structures that we design not to absorb wave energy. So a ship is designed to be of such a length that it doesn’t pitch violently or everyone to get seasick on the ship. So vessels and oil and gas platforms are designed not to resonate with the wave, because you want the platform not to fatigue and fail prematurely. Now we have to design structures that very efficiently take in all that energy. So that’s one of the challenges too. It’s a whole new mindset.

MEGAN THOMPSON: It’s difficult to develop this technology. It’s still in the very early stages, but you do believe that you are gonna get to commercial viability one day?

PAT CROSS: I do. You know, there are, it’s, can I guarantee? No. But I think there’s a lot of enthusiasm in the wave energy business right now. The prize is great. There’s a lot of energy out there, and it’s really, just makes, it wouldn’t make sense not to pursue wave energy as part of– the– the world’s, the Navy’s and the country’s and the world’s– power needs.

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