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PRI's Environmental News Magazine

Wave Power

Air Date: Week of September 7, 2001

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Researchers have been trying to harness the power of the waves for more than thirty years, and they're beginning to succeed. Living on earth's Cynthia Graber reports.

Transcript

CURWOOD: For billions of years, waves have rolled relentlessly across the surface of the oceans. And now, humans are trying to harness the energy generated by the pounding of the surf. Living on Earth's Cynthia Graber reports.

GRABER: If you've ever been in the ocean, you've felt the knock-down, drag out power of the waves. Wave power is actually concentrated solar power. Here's why. The sun heats up the earth, but it does so unevenly. The differences in temperature create wind. Wind over water creates waves. Scientists and engineers have spent the past three decades trying to harness wave power for our own use, and, last fall, the first wave power electricity generator began providing power for a few hundred homes on a small Scottish island.

THOMSON: It's off the west coast of Scotland, the lowest of the western isles, and it's very rugged. It's more famous for its malt whiskeys. I won't list them all because there's quite a lot of them.

GRABER: Allan Thomson is managing director of Wavegen, the company that operates the Scottish facility called the Limpet. Thomson says the coast of Scotland is ideal for a commercial wave power generator.

THOMSON: Well, it has to be where there's a resource to begin with. The longer the wind has to blow on the sea, the bigger the wave. The west coast of Europe is fantastic.

GRABER: The device is basically a concrete box built into the side of a cliff, with an opening at the bottom. Thom Thorpe, of AEA Technologies in the U.K., is an expert on wave technology and consultant on the Scotland project. He says this particular system is called an oscillating water column. As the waves crash into the concrete box, the water level inside the box rises and falls.

THORPE: Above that column of water is an air space, and as the water goes up it compresses the air and drives it through a narrow funnel, and in that funnel is placed a turbine. That basically is a simple description of quite a complicated bit of technology which has taken a long time to optimize.

GRABER: Indeed, it hasn't been easy to get to this stage. Harnessing wave power comes with one big risk: the ocean itself. Following the oil shortage of the 1970s, the U.K. took the lead in wave energy research. But a massive prototype power station, many times larger than the current facility in Scotland, was destroyed in the water.

THORPE: If I've learned nothing else in wave energy, it is the fact that the sea always holds surprises, and we can never be 100% confident of how something is actually going to behave in the sea.

GRABER: Later tries were also destroyed. But in these first attempts the power stations were located off-shore. The Limpet has been more successful because it is located on the shore. Although waves lose much of their power by the time they reach it, they retain enough to create electricity. Electricity generated by the Limpet costs about three times as much as energy generated by conventional coal or gas-fired plants. Experts expect the costs will quickly come down as larger generators are built. The Limpet's continuing success is drawing an influx of government and private funds into wave research. But this device is only one of many on and off-shore devices currently in development.

[SOUND OF HYDRAULIC WAVE MAKER]

McCORMICK: This is a hydraulic wave maker. This thing, all it does is, you push it back, push the bulkhead back and forth and it generates waves, as you'll see.

GRABER: Michael McCormick is an ocean engineer, and probably the American expert on wave power technology. He's standing in front of a huge tank full of water that simulates waves in the ocean. Here at the U.S. Naval Academy in Annapolis, he used this tank to test the prototypes for an off-shore wave power pump expected to go into the water off the coast of Ireland in October. McCormick believes that it is much more efficient, and more useful, to take wave energy and use it to make potable water from the sea, rather than electricity.

McCORMICK: I would say that 95% of the projects are devoted to electrical energy conversion, and it's simply because we have been so ingrained with the idea that we cannot live with electricity. But, quite honestly, I can go a couple of weeks without using electricity. I'd suffer a little bit, but I'd suffer a lot more if I didn't have water.

GRABER: The pump will take salt out of enough water to supply the needs for an American town of about 2,000. It works like this: The energy from the waves is transferred to a hydraulic pump. The pressure from the pump forces sea water through a membrane, letting the water through and leaving the salt behind. The process costs a fraction of what it takes to desalinate sea water using conventional methods.

McCORMICK: I'm not saying that the McCabe wave pump is going to solve the water crisis throughout the world. I'm saying it's a start. Let's look at the island population. We have 100,000 inhabited islands. One McCabe wave pump can sustain a lot of life on a desert coast or on an island community.

GRABER: Whether to provide drinking water or electricity, wave energy is still very much in its infancy. This year, at least three different models for electricity generation will be placed in the water around the world, with more in development. The best designs will take advantage of the vast amount of energy embedded in the rise and fall of the swells, and be able to withstand their force.

For Living on Earth, I'm Cynthia Graber.

[MUSIC]

 

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