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Posted By: lyledunn Tide power - 04/18/05 06:10 PM
I live reasonably close to Strangford Lough in the north of Ireland. It has a narrow mouth and funnels millions of gallons of tidal water at speeds up to 14Km/hr. It has always impressed me as an ideal location for an underwater, environmentally benign turbine plant. You cannot fail to be impressed by the power of the water that ebbs and flows here in the tidal cycle. The experience of power is especially enhanced when you are aboard a 200HP fishing boat that barely makes way! However, they are doing some experimental work with the bedrock to ensure that the turbine can be anchored securely. Apparently the turbine is to be fitted with huge blades much like a wind turbine. This surprised me somewhat since I perceived water turbines to be more of a funnel device. Are blades the usual method?
Disappointingly, the turbine is to power only the equivalent of 600 houses.
Posted By: SimonUK Re: Tide power - 04/19/05 12:38 AM
I have also often wondered why the tidal flow at Strome (Lochcarron), Balachulish (Loch Leven), Connel (Loch Etive)and Corran (loch Lihnie) has not been harnessed. The only setback is at slack water when the tide turns every 6.5 hours.

Posted By: Hutch Re: Tide power - 04/19/05 08:11 AM
For maximum power generation and efficency you need a good volume, a steady head of pressure over the longest possible time and not just high velocity flow - plenty of electrical analogies here. For this you need to use the barrier method. [Linked Image]

Used very successfully at St Malo in northwest France. I remember the place well from my days as a geology student. Our lecturer, the late and much lamented Stuart McKerrow was a superb fellow, ex-Royal Navy with tales of daring do off Alderney in WW2 and a favoured last resting place for good whisky. Our Brittany field trip started with some coastal rock exposures that could only be reached at low tide and our intrepid ex-matelot was detailed to schedule this part of the visit being familiar with tide tables etc. As it turned out it happened to be the first stop of a memorable week.

Imagine our surprise, as they say, when our small convoy of Ford Transit vans is brought to a halt line astern in a narrow French lane by an expanse of seawater. The outcrops are flooded – how could Her Majesty’s finest ex-serving officer of the Fleet have got it wrong? It soon became clear that the outcrops were on the inside of the St Malo tidal barrage and that, in producing power on both the ebb and flow tides, the “tides” inside the barrier were 90° out of phase of the real tides on the sea side of the barrier. Much healthy ribbing ensued and the first stop was abandoned.

For good tidal power you need a site of enhanced tidal range and funnel shaped estuaries where many tidal flows come together are favoured. In the UK, the Bristol Channel has the highest tidal range – it is host upstream to the famous Severn Bore. Studies have been conducted into the feasibility of a tidal power station here. The Bay of Fundy, between Nova Scotia and New Brunswick in Canada has the highest tides in the world and can reach a range of 16m (52½’ for Paul [Linked Image] ) . It would make an excellent tidal power site but like all these things, including wind turbines, there are environmental issues.

[This message has been edited by Hutch (edited 04-19-2005).]
Posted By: lyledunn Re: Tide power - 04/19/05 09:45 AM
Thanks for the interesting aside. Well told!Thanks also for the link.
It appears that there has been some renewed interest in tidal power by private commercial enterprises, spurred no doubt by profit, but nonetheless an important contribution to establishing a wide port-folio of renewable sources for our seemingly insatiable demand.
Posted By: SimonUK Re: Tide power - 04/21/05 10:04 PM
Very interesting.

When I worked on my uncles fishing boat we would on occasion move the fleets of creels to the sound of Raasay (raasay is an Island on the north west coast of Scotland).

Any way to cut a long story short the creels were always cast over in the same direction no matter what time of day or month. This is because the tide always flows north in the sound no matter what.

I guess what I'm saying is that there must be more suitable places than the sound as the dimensions are far too big to harness.

If you look at the volumes of water behind the four places I suggested in my previous post it is surprising that nothing has been done to harness this energy, after all pump storage isn't exactly efficient.

From personal experience I know slack water only lasts a few minutes at Strome, the narrowest part of Loch Carron.

At connel the tide actually falls faster than the loch can empty and creates a waterfall.

I'm working long hours just now and have had a couple of beers so if it seems I'm rambling I apologise, I find it hard to put my thoughts into words at the best of times.

Posted By: Trumpy Re: Tide power - 05/04/05 11:49 PM
Good call Lyle.
I agree, tidal power generation should be harnessed more than what it currently is.
If you put the cost of initial installation aside, it's basically free power.
There was a new tidal generation station just commissioned in Australia that used a tubular turbine system, but I can't remember where exactly it was in Aussie.
Can any of our Australian members help?. [Linked Image]
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