JUN 01

Tidal power systems have been under investigation for many years. The earliest method to generate power was with 'barrage' systems, which required the construction of dams across inlets and bays. Gates in the dams allowed the basin to fill during high tide, then the gates would be closed, and the basin would be allowed to drain out through turbines to generate power. However, the environmental impacts of these systems, along with the cost and the relative inefficiency, have kept them from much further development. There are some 'barrage' installations still in operation in Canada and in France, but no new projects are planned.

Instead, tidal power is being pursued as basically the same way wind power has been developed, turbines. In-line tidal power is intriguing because it is much more regular and predictable than wind, which can be intermittent and is much more dependent on local weather. Water also has a much higher energy density than air does, which makes tidal systems appealing because a water turbine can be smaller than an air turbine.

A tidal power system comprised of six 35-kilowatt turbines has been installed in the East River near Roosevelt Island, New York. This study system is meant to determine the best configuration for the equipment, and help develop easily mass-producible versions of the turbines. A final configuration of 100 turbines is anticipated at this location.

Preliminary site approvals for in-stream turbine farms have already been given for 25 sites along the Atlantic and Pacific coasts of the US, and a further 31 sites are under consideration. Other companies are developing other forms of tidal turbines, some with as much as 1 megawatt capacity.

Previously on EcoGeek

via: MIT Technology Review

Comments (13)

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Flexibility
written by kballs, June 02, 2007

Seems like these could be installed just about anywhere under the low tide line, including underneath docks which don't have any worries about boat traffic running them over.

I'm sure there will be people complaining about chopping up fish with the blades (though probably less than the people whining about birds in wind turbines), maybe they need grills (though they would require REGULAR cleaning so they don't get clogged with mussels and barnacles - which will attach to ANYTHING no matter how glassy or non-stick it seems).

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Seems like a good idea!
written by Vinas, June 26, 2007

I think the smaller more mass production type tubines make a lot of sense on a few different levels. A friend of mine just produced his first blade for his wind turbine operation. I showed him this article and he was quite interested. I agree about the barnacles and mussels. They are so hard to clean that I think it might kill the idea all together! Here in Michigan the mussels costs millions of dollars in managment expenses. If they can figure out a way to keep the mussels from being a problem, I could see this really taking off. 8)

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Other options
written by Jonathan Harpur, June 26, 2007

I would think these would have a fairly successful return in locations such as rivers and active floodways - and wouldn't be any more ecologically harmful (on the fauna level - slicin' and dicin' - anyway) than a hydroelectric dam would - probably much less so. Most fish aren't that blind.

One thing that may have to be considered is ice flows. If the area is prone to icebergs, like the eastern seaboard of Canada (World's highest tides! ...whee.) you'd need to make sure the turbines are protected. Where I'm from both ice and silting would be an issue.

As for location, almost anything deep enough and out of sealanes could be charted as a hazard for boaters with a deep keel.

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RPM's?
written by Mark, June 26, 2007

Don't the blades (like those of wind turbines) spin at a relatively slow rate? It's not like a boat propeller where a fish just passing by would be shredded. As I understand it, these intend to provide semi-regular long term energy by continuously spinning slowly...

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Electrocute the barnacles?
written by C, June 27, 2007

Let's use some of the power generated to electrocute the barnacles, then maybe they'll stay away.

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Holistic source of the energy
written by James, June 28, 2007

The coolest thing about tidal power is that, unlike any other form of energy (well, that and geothermal), it's ultimate source of energy isn't the sun. With fossil fuels, you're burning stored solar energy in the forms of ancient plants and animals; wind power is generated by temperature differentials caused by the sun; hydroelectric plants are powered by falling water, and the water gets its potential energy when the sun evaporates it and carries it up. However, the energy from the tides actually comes from the moon's gravity pulling on the oceans. So that's pretty neat.

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barnacles and current
written by angelo, August 03, 2007

I don't know how those boat people maintain a barnacle free propeller, if they can do it or if there is natural explanation to it then tidal power system infrasructure maintenance on that matter will not be a problem. As for the ecosystem, the water whirl that will be created by the turbine will help the movement of sea nutrient that will attract school of fishes, as to fishes being hit by the blade, I think they are instinctive and fast enough. It is the divers who should be more concern being suck or hit by the blades specially when there is the shift of tide where the current will be strong.

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good points all around
written by grey, December 06, 2007

I agree with whoever raised the point of barnacles attaching to the blades. IMHO that would be the biggest problem. Anti-barnacle paints and coatings are extremely toxic so their use would probably negate any benefits from using this technology.

I have a feeling though, that barnacles wont attach to something if it's moving fast enough and continuously. I might be completely wrong about that, but it would make sense wouldn't it?

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vertical axis water turbine
written by mekanizmalar, February 11, 2008

The proposed tidal turbines with rotating 3 or 2 blade designs require deep tidal basins. This limits their potential use. The best alternative to this one I believe vertical axis turbines with small flaps attached on their blades. I recently added a simple turbine design to youtube http://www.youtube.com/watch?v=M0V0GXYeFgM
which might do just that. If barnacles attaches to small flaps, just replace the flaps which can be manufactured from inexpensive materials. It is also not require that this turbines should be attached to the sea bed. They may be installed underneath of big floating platforms. This kind turbine also perform on shallow waters.

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where?
written by taylor, March 18, 2008

where are you guys located?

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Barnacles
written by jim, July 20, 2008

Harvest the barnacles and eat them. We get two benefits from one process. We could even get a good export market going with France, since they live they love the little limpets.

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OMFG
written by Craigen, October 13, 2008

:P :P :P :P :P :P :P :P

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So......
written by ayebeach, December 17, 2008

when looking through the types of turbines there are what kind of turbine would you guys suggest to be the best kind to use underneath say a dock or something?

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