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Author Topic: Ocean Flow tidal turbine  (Read 3694 times)
camillitech
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« on: October 23, 2016, 08:48:04 PM »

Was in Campbeltown last night and saw this on the pier.



It was there last year but I believe it's been in and out of the water since then, local chap says it was hit by a boat. It's called an E35 which I think means 35kW but I'm guessing it'll only be delivering that at spring tides and then only for the middle of each six hour period according to the 'rule of twelfths' https://en.wikipedia.org/wiki/Rule_of_twelfths. Of course that could be just me being cynical and the figure comes from the average over a two week period  whistlie Sadly, experience has taught me otherwise, you just have to look at inverter nomenclature  Roll Eyes Don't get me wrong, I think there's much to be said for tidal and wave power, once you get by the hype.

Hope it does work, or even just prove a useful stepping stone for further innovation. Sadly a neighbour of mine has a son that worked in the wave power industry for a while and became disillusioned. Here's hoping hey https://lifeattheendoftheroad.wordpress.com/2016/10/23/a-taste-of-home/

Cheers, Paul
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'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
smegal
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« Reply #1 on: October 24, 2016, 11:42:22 AM »

"Oceanflow's 35kW Evopod unit has completed the first phase of its in-sea trials to demonstrate the reliability of key systems and components. E35-01 has been deployed in Sanda Sound for over one year to test mooring system components, power electronics and subsea power distribution systems. The ľ scale device which incorporates a number of key technologies developed by Oceanflow has recently been recovered to Campbeltown Harbour after being continuously deployed in Sanda Sound, South Kintyre from the 7th August 2014 to the 7th September 2015."


"The unit is currently on Campbeltown quayside being prepared for re-deployment at Sanda Sound. When reinstalled on its moorings the generating device will be hooked up to a subsea transformer unit sending power back ashore into the grid at Southend."

http://www.oceanflowenergy.com/news26.html
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camillitech
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« Reply #2 on: October 24, 2016, 01:18:08 PM »

Oceanflow has recently been recovered to Campbeltown Harbour after being continuously deployed in Sanda Sound, South Kintyre from the 7th August 2014 to the 7th September 2015."


"The unit is currently on Campbeltown quayside being prepared for re-deployment at Sanda Sound. When reinstalled on its moorings the generating device will be hooked up to a subsea transformer unit sending power back ashore into the grid at Southend."

http://www.oceanflowenergy.com/news26.html

Aye but that was over a year ago now so did it ever get redeployed or has it been sat there ever since?
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http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
smegal
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« Reply #3 on: October 24, 2016, 01:43:31 PM »

Oceanflow has recently been recovered to Campbeltown Harbour after being continuously deployed in Sanda Sound, South Kintyre from the 7th August 2014 to the 7th September 2015."


"The unit is currently on Campbeltown quayside being prepared for re-deployment at Sanda Sound. When reinstalled on its moorings the generating device will be hooked up to a subsea transformer unit sending power back ashore into the grid at Southend."

http://www.oceanflowenergy.com/news26.html

Aye but that was over a year ago now so did it ever get redeployed or has it been sat there ever since?

Looks like it's just sat there.
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Billy
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« Reply #4 on: October 24, 2016, 01:50:25 PM »

Sarfend, they'll still be saving up for the cable then.......  hysteria
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JohnS
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« Reply #5 on: October 24, 2016, 06:12:43 PM »


I'm guessing it'll only be delivering that at spring tides and then only for the middle of each six hour period according to the 'rule of twelfths' https://en.wikipedia.org/wiki/Rule_of_twelfths. Of course that could be just me being cynical.

Cheers, Paul

I beg to differ.  The rule of twelfths applies to tidal heights.  If one looks at the tidal currents in a tidal atlas or the tidal diamonds on a chart, one will see a more even distribution.  Slack water is for a relatively short period.  The moon and the sun pull the water horizontally and the topography of the coast and seabed funnel the flow and cause the vertical movements.

John
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dhaslam
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« Reply #6 on: October 24, 2016, 07:24:33 PM »

The change in height of tide could not be dissociated from the flow.   There is also another problem  in that the power output  presumably  varies by the cube of the  flow  velocity like wind turbines. 
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camillitech
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« Reply #7 on: October 24, 2016, 08:21:28 PM »


I'm guessing it'll only be delivering that at spring tides and then only for the middle of each six hour period according to the 'rule of twelfths' https://en.wikipedia.org/wiki/Rule_of_twelfths. Of course that could be just me being cynical.

Cheers, Paul

I beg to differ.  The rule of twelfths applies to tidal heights.  If one looks at the tidal currents in a tidal atlas or the tidal diamonds on a chart, one will see a more even distribution.  Slack water is for a relatively short period.  The moon and the sun pull the water horizontally and the topography of the coast and seabed funnel the flow and cause the vertical movements.

John

You can 'beg to differ all you like John, the change in speed and height are directly related in most locations. There are exception like around the Isle of Wight, Corryvreckan, and other places where tides meet and sea bed topography is complicated. Just as wind gets confused around tall buildings  but on on the whole they are directly related. I spent 18 or more years diving for clams and many more as a hobby, believe me the speed of the tide in such an occupation is crucial. It is at at fastest around mid tide and slowest either side of slack water, I've dived from the Scillies to Shetland so have a pretty good idea of what I'm talking about. Tis one thing making these kind of observations from a yacht, quite another trying to swim against a knot of tide with a bag of scallops  Grin

Cheers, Paul
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'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
charlieb
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« Reply #8 on: October 25, 2016, 11:49:44 AM »


I'm guessing it'll only be delivering that at spring tides and then only for the middle of each six hour period according to the 'rule of twelfths' https://en.wikipedia.org/wiki/Rule_of_twelfths. Of course that could be just me being cynical.

Cheers, Paul

I beg to differ.  The rule of twelfths applies to tidal heights.  If one looks at the tidal currents in a tidal atlas or the tidal diamonds on a chart, one will see a more even distribution.  Slack water is for a relatively short period.  The moon and the sun pull the water horizontally and the topography of the coast and seabed funnel the flow and cause the vertical movements.

John

You can 'beg to differ all you like John, the change in speed and height are directly related in most locations. There are exception like around the Isle of Wight, Corryvreckan, and other places where tides meet and sea bed topography is complicated. Just as wind gets confused around tall buildings  but on on the whole they are directly related. I spent 18 or more years diving for clams and many more as a hobby, believe me the speed of the tide in such an occupation is crucial. It is at at fastest around mid tide and slowest either side of slack water, I've dived from the Scillies to Shetland so have a pretty good idea of what I'm talking about. Tis one thing making these kind of observations from a yacht, quite another trying to swim against a knot of tide with a bag of scallops  Grin

Cheers, Paul

Tidal turbine nameplate capacity smoke and mirrors is much like wind turbines. Ie not a time average - no generators are that I know of - but a measure of peak output (aka rated capacity).    Sensible designers will rate their turbine at a bit less than peak tidal velocity at a particular site, which would lead to a pretty good Capacity Factor.   The smoke-and-mirrors come when fairly small rotors are rated for infeasibly high flow velocities, which might sound nice (the biggest tidal generator in the world, etc) but leads to very low capacity factors. 

For the particular sites that tidal flow generators might work I'm with John S - the hydrodynamics become very complicated and there are likely to be flows for more of the day than rule of twelths would suggest.  If anyone's very interested there's info here:  https://www.carbontrust.com/media/77264/ctc799_uk_tidal_current_resource_and_economics.pdf     (I wrote the foreword.)    In fact it would make tidal energy engineering MUCH easier if there were reliable slack tides, as installation is such a huge part of project costs.

The core learning from that work was that it's only ever going to be commercially viable to site tidal turbines in a relatively small number of places with very high flows (not surprising really, but seemed to be news to some people), ie where funnelling or resonances make 'normal' flow patterns break down.      The Capacity Factor for MCT's Seagen turbine at Strangford Laugh has been up over 60% when operating - because the site is unique, and because the designers rated it sensibly.    Other sites will be aiming for Capacity Factors above 35% imo, much like wind.     That said there's a fair bit of energy to be got in those relatively few sites - Pentland Firth alone stands out a mile. 
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camillitech
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« Reply #9 on: October 25, 2016, 10:35:26 PM »

Whilst I've never been to university or written anything other than me blog I have spent 40 years on, in and under the sea and most of that has been sport or work scheduled around the speed an height of tides. Working with the height being crucial for getting me boat in and out of a pier and height for maximizing 'bottom time'. Speed and direction be absolutely crucial for using the tide to it's maximum advantage. If you're working a small area atop a reef or in a narrow channel you need to know exactly when 'slack water' is and how long it lasts. After a few years you get a 'feel' for it and you know that the charts and 'tidal stream atlas' are at best a good tide. you know that the 'ebb' of high water always turns quicker and moves faster than the 'flood' at low water. You know that in most places the tide goes our faster than it comes in. If you work with scallop lanterns, fish cage nets and lifting scallops off the sea bed for a living you observe these things because utilizing them to your advantage makes you money. Trying to fight nature costs you money and makes you tired. If you want to 'cover ground' quickly cos the clams are sparse you dive at mid tide, if you're on a good patch and it's deep you do it at LW slack.

I did this three times a day six days a week for 15 years in all weathers, at all times of the year and around an awful lot of coastline. Sure the topography can have a huge effect, just as it has on wind. However only a wind turbine salesman or complete numpty would site a wind turbine in turbulent air. Surely the same applies to a tidal one, at the end of the day you cannae get away from the fact that the tide moves a good deal faster in 99 places out of a 100 around 3 hours after either high or low water. Sure it always moves a little quicker on the ebb and may flow upwards when it hits reef or pinnacle, indeed in some places it flows vertically downwards sweeping you into unsafe depths. However, these are by far and wide the exceptions, sadly they are probably the places where the 'experts' think you should put a tidal turbine.

The windiest place by far on the Isle of Skye is Sconser, you would think it the best place to put a wind turbine. I have seen the wind at Sconser smash the windows on half a dozen parked cars, pick up a Volvo estate and park it in the sea. Yet it is so turbulent there that I doubt any wind turbine would last long or produce exceptional energy. Surely the last place would put a tidal turbine is somewhere where the tides are vertical, turbulent or unpredictable.



It was a hard living clam diving but I wouldn't have swapped it for anything at the time.



My son who's now 17 came out with me every single day from an early age learned to count aboard the good ship MV Conqueror



I guess that's why he's so good at maths and unlike his dad, he will go to uni, sadly, at the moment he's got 'feck all' in the way of common sense but hopefully that'll come with experience  Grin

Sorry Charlie, John, I disagree, Paul
« Last Edit: October 25, 2016, 10:39:16 PM by camillitech » Logged

http://lifeattheendoftheroad.wordpress.com/

'Off grid' since 1985,  Proven 2.5kW, Proven 6kW direct heating, SI6.OH, 800ah Rolls, 4.75kW PV ,4xTS45, Lister HR2 12kW, , Powerspout pelton, Stream Engine turgo, 60 x Navitron toobs and a 1500lt store. Outback VFX3048 and 950ah forklifts for backup,
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