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Andrew Zimmerman Jones

Energy from the Motion of the Ocean

By June 4, 2006

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A Scottish company, Ocean Power Delivery Ltd. (OPD), has developed a device that resembles a mechanical snake. It's red, 450-feet long, and floats in the ocean, none of which is much like the sea snake for which it is named: Pelamis. The ocean waves cause motion which is converted, through hinges hooked into electricity generators, into electricity that is transmitted to shore by cables. The both the horizontal and vertical movement of the wave energy is utilized in these devices to generate an average of 70 kilowatts (kW) per yard, depending upon the wave conditions.

Of course, waves aren't uniformly distributed across the world. Like oil, it's a matter of lucky geology, as well as the Earth's rotation, as to what areas will most benefit from the Pelamis's energy production. The east coasts of Africa, Asia, and Australia would generate merely an average of 20 kW per yard, which means they may want to look for other energy alternatives for those regions.

The Pelamis has generated enough interest for a Portugese consortium, Enersis (yes, I know it's in Portugese, but I figured I'd provide the link anyway), to invest in 31 of the machines (3 were to be delivered in May, according to OPD). They plan to create a 2.25 megawatt (MW) "wave farm" (artist's rendition to the left) off the northern coast of Portugal, as an initial step toward a full 24 MW plant. (For an idea of scale, here are some Pennsylvania clean energy initiatives from 2005, with their relative power generation indicated.)

The design of the Pelamis should allow it to survive the dark fate of other attempts to garner energy from waves. In swells as high as 10 times the average wave (and 100 times the power), the Pelamis should remain anchored, its sleek structure allowing it to dive into the wave as needed without suffering harm.

Further details on the device can be found through a December article from Discover magazine.

With oil prices still high, it's a veritable boom time for the alternative fuel industry. As we've discussed before, there is a lot of talk on the subject, including:

Images: Provided upon request by Ocean Power Delivery, Ltd.


June 5, 2006 at 4:32 am
(1) c sil says:

the enersis link is actually spanish not portuguese

November 18, 2009 at 6:11 am
(2) Dion krige says:

Hi, the wave energy is derived from the moon-earth rotational system. While these attempts to retrieve energy from this system are miniscule, theoretically if we extract enough energy from the system….the moon will fall (or the sky as Chicken Licken said!). So is this “green” energy or just like nuclear energy, eventually will cause major environmental problems? Dion

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