JAN 31

A demonstration installation for a new method of electrical generation using tidal power is being planned by Nova Scotia Power and Open Hydro, an Irish technology developer. This method of tidal generation may prove to be more widely usable than current methods of harnessing tidal power.

Nova Scotia Power currently operates the only tidal power generation plant in the western hemisphere. But that facility relies on dams and storage ponds, and is functionally akin to standard hydroelectric generation. "A large dam called a barrage is built across a river or outcropping of land. The dam funnels the water into the tidal generating plant as it flows in and out with the tide. To produce practical amounts of tidal power, a difference of a least five metres between high and low tide is needed. There are only about 40 sites around the world with this kind of tidal range. Currently in Canada, the only practical site is the Bay of Fundy." (from Nova Scotia Power)

In contrast, the new system will sit on the seabed and will require no dams or large structures for operation. The in-stream tidal power system is analagous to a wind turbine, sitting in a flow and drawing power from it. But unlike wind power, the in stream tidal generator has a regular source of energy from the cycling of the tides.

Open Hydro cites three primary advantages for tidal power:

• Energy produced is completely predictable.
• Turbines are located beneath the surface and cannot be seen or heard.
• Water is 830 times denser than air meaning that a much smaller turbine is needed to generate the same volume of electricity.

These are all good points. The most significant drawback to tidal power is that it is constrained to coastal locations with strong tidal flow, which limits its applicability. It isn't going to be the only energy solution for the future, but where it can be installed, it looks like it will be a great option in the sustainable power generation portfolio.

via: CBC Tech News

Comments (15)

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written by per, January 31, 2007

The other, more common way of extracting tidal power is to use some sort of piston that rises and falls with the waves. I wonder how the two methods compare? I suspect that the turbine approach requires careful placement of the device, while the piston types could be placed just about anywhere near the shore.

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written by Mctavish, January 31, 2007

Tidal power and wave power are entirely different I'm afraid.

Tidal power uses the regular and predictable movement of water due to the gravitaional pull of the Moon and the Sun, combined with the rotation of the Earth.

Wave power is the harnessing of energy transferred by the wind to the sea. The wind generates swell, and is not nearly as predictable as the steady rhythm of the tides.

I think this idea has merit providing that an array of turbines doesn't produce a dead spot which the tidal currents flow around.

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good, but could be better
written by ~R, February 02, 2007

Throw a wind turbine on top of that structure and multiply it's capacity.

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Fish + Turbine?
written by Wulf, February 04, 2007

I've heard that depending on the location, wind turbines can be bad for birds, as they can accidentally fly into the blade. I wonder if this system would do the same for fish (and other miscellaneous marine life)…

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written by Philip Proefrock, February 09, 2007

Wulf--

You'll notice that there is a hollow spot at the center of the turbine to deal with this issue.

I like the idea of merging in-stream installations and wind turbines. I'm not sure if there are locations where both would work sufficiently well (particularly since there are not a lot of good locations for in-stream installations), but it's an engaging concept.

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Sound affect on fish... Weird stationar
written by Steve Nordquist, February 18, 2007

Lighter security certification for oceanography here...maybe good!
Shellfish that evolve (less naturally) to jump through hoops...awesome! XTreme 400lb. crab hunting 2310?
Having to wait to high tide to go out and get a cup of power...meh.
Destination restaurant with estuary management theme...hasn't this been done?

Not in Cuba, you say? Hm....

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Power production?
written by katie, March 12, 2007

How much power does this open hydro thing produce? Is is as much/more as a conventional turbine?
Looks Great!

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written by I Have a question, March 20, 2007

I was wondering if tidal power effects the environment in a negative or positive way?

and is it expensive or too expensive?

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Water Speed
written by Dirk, April 09, 2007

Hi - Interesting
1. what speed of water : power generation relationship will exist?
2. Leap tides will sureley generate more power??
3. Will water not just flow around the hurdle / obstruction? It is not space restricted like in a river.
4. Can this then also be used in a river? What do you estimate the minimum flow speed to be and will a funnel to concentrate the flow increase efficiency?
5. The fish through the turbine can also assist in additional income from sushi..... so don't worry, much less impact than burning coal

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written by Bert, April 23, 2007

I'm developing curriculum for a one credit/unit course "Introduction to Tidal Power Generation." There is a lot of information available - but what do you think would be important and still introductory on this subject? Thank you for your help.

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written by Carolyn, June 19, 2007

I like the idea above that R suggested; "throw a wind turbine on top of that structure and multiply it's capacity." That's thinking outside the box! As for fish and the in-stream system, the design is a sound one, and assuming the blades don't rotate faster than 30 rpm's per minute, fish can pass through unharmed.

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Western hemisphere doesn't start in Newf
written by BrendanH, August 31, 2007

Just to be pedantic: it's not the only tidal generator in the western hemisphere. The Barrage de la Rance, between Dinard and St Malo in France is also in the western hemisphere. Only 2 degrees west perhaps, but not east!

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Spheres in the Ocean?
written by mountain girl, July 14, 2008

WHat if you had some sort of sphere that sat out in the open ocean with a gyroscope inside that would create kinetic enengy as the waves tossed it up and down?

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TIDAL ENERGY NOT "RENEWABLE"
written by ROBERT GRUBER, December 24, 2008

THE ENERGY OF THE TIDES, WAVES, AND WIND HAVE TO COME FROM SOMEWHERE. BLITHELY THINKING IT'S RENEWABLE BECAUSE WE DON'T KNOW, FOR EXAMPLE, HOW HARNESSING TIDAL POWER WILL AFFECT THE EARTH/MOON DISTANCE OR EARTH'S RATE OF ROTATION IS SHORT-SIGHTED. IT'S AKIN TO PEOPLE UNTIL RECENTLY BURNING FOSSIL FUEL WITH NO CONCERN FOR THE EFFECT IT WOULD HAVE ON THE ATMOSPHERE AND TEMPERATURE; MAYBE EVEN ALTERING GROSS WIND PATTERNS AND OCEAN CURRENTS.

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RE: Tidal Energy Is Not "Renewable"
written by David, August 10, 2009

This was something of question for me for awhile. We've all been told that the tides and tidal energy come from the gravitational pull of the moon. I wondered "were does that energy come from?" "how can one harness the power of a continuous gravitational pull without some effect?" The truth is that Tidal Energy is a renewable source of energy like the sun is a renewable source of energy, eventually our star the sun will burn out just as eventually the moon's orbit will decay and either spin off into space or come colliding into earth. These events will not occur for BILLIONS of years, though. Unharnessed, the kinetic energy of tides is dissipated as one water molecule bumps into another and is largely turned into heat. If we instead transformed this kinetic energy of the tidal flow into electricity it would only serve to lessen this and would have a wholly negligible effect on the temperature of our massive oceans. There are many environmental concerns to be considered here, but, I don't think this is one of them.

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