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Ocean Waves Offer Alternative Energy Source


For much of the latter half of the 20th century, scientists speculated that the power of the pounding ocean surf might be a potential source of clean, renewable energy. Recently, an experimental contraption built off the coast of Scotland has brought that possibility a bit closer to reality.

Anyone who has ever sat on an ocean beach has experienced personally the raw energy of the sea. According to Tracy Staedter at "Technology Review" in Cambridge Massachusetts, interest in the practical uses of that energy is on the rise. "Wave energy is another form of alternative energy in the way that wind energy generates energy without fossil fuels, or reduced amounts of fossil fuels," she says. "You know, when you are at the beach, you can see the waves are coming in and they are rising and falling. When you're fishing, and your "bobber" is sitting on the water, you see that, as the wave comes over, the bobber goes up and down and up and down. So that's energy. That's a kinetic energy. And scientists have been looking at ways to harness this."

Some ways of doing that would be to put something on the water that floats. And as it moves up and down with the waves that is capturing the wave power of that up and down motion."

An experimental wave energy machine was installed recently off the coast of Scotland. It's called the Land-Installed Marine-Powered Energy Transformer or "LIMPET" for short. LIMPET can generate enough electricity for about 400 homes on a nearby island. "They have a gigantic oscillating chamber which is gigantic sort of concrete chamber that is set up by the shoreline. And as the waves come in, they go into the chamber, and the air pocket that's inside this chamber is compressed," says Tracy Staedter. "And the air that is compressed is forced through a small hole that is by a turbine. And the air moving across the turbine then spins the turbine which has inside of it a magnet that is wrapped with coils and as the magnet spins around, it generates an electric field. And that energy is harnessed and fed into a power grid."

Q: And the power grid is what we use to light our homes and to have other electronic uses?
A: Exactly. That is where we get our energy from.
Q: What are the advantages of wave energy? Certainly there are enough waves in the world…!
A: I think the biggest advantage really is that waves are free. It doesn't cost anything besides building this contraption, really and we don't have to pay as much for it as we would fossil fuels.

In order to make it economically viable, what you want to do is harness the most wave action in the smallest amount of space. I mean you can't build this gigantic contraption along the shore that goes on for miles and miles and miles, because then you don't have anymore beach or shoreline. The biggest challenge is they [waves] are very erratic, they vary in their energy, sometimes they are small waves, sometimes they are gigantic waves. It's a little inconsistent."

That is why, according to Ms. Staedter, this technology is still in its early experimental stages. "The LIMPET is the closest to providing energy to homes… but it's not supplying the whole island with energy. It's helping," she says. "It's contributing to the energy grid on this particular island. But I think everything is still in that stage where the cost of it has to come down before we are going to see it in the United States, at least."

But Tracy Staedter of "Technology Review" adds that Americans are working on the problem. In California, she says, the state energy commission is studying the viability of ocean energy, and San Diego State University is assembling a consortium that one day could help to make the widespread use of wave power an American reality.

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