Talk:Tidal power/Archive 2

Tidal stream or barrages layout corrected

If the Tidal Stream is the first heading then the fist dot point should be Tidal Stream not the other way round. 210.9.237.1 (talk) 04:46, 28 March 2008 (UTC)

Please explain

Can someone please explain why some companies are allowed to put information (text & graphics) on the article page/s and elswhere have their own page, while others with similar endeavours are deleted? There seems to be a simialr vein of COI but the Wiki laws are administered differently allowing some and not others. Tidalenergy 22:56, 8 October 2007 (UTC)

Verbiage Removed

Due to a complaint I have removed the clutter and "vast amount of veribage" that I placed on this page that brought the newer more popular tidal stream technologies into the discussion. I hope it does not meet with any disapproval.

Also I elevated the tidal stream to top billing as there are only three barrages globally (correct me if I am wrong people) with the far more popular tidal stream (dozens of technologies world wide with many mores sites and commercial deployments) up the page so as to better represent the subject.

Again I hope this does not meet with the general disapproval of the majority of editors.

I note that one editor in particular has a bias for barrages and that this will upset them. But in the interests of a fair and just representation of the industry I am of the firm opinion (without bias) that this is the right and correct thing to do.

Regards Tidalenergy 02:11, 2 October 2007 (UTC)

shrouded turbine facts

A shroud or venturi that encases a turbine like a duct can improve turbine performance by up to 384% (compared to the same turbine in free stream) as reported by Dr. Brian Kirke a PhD in turbine design in 2002. (I am new here and do not know how to up load the report --- perhaps someone can assist me) While shrouded or ducted turbine technology is not new it represents a quantum leap in turbine technology by allowing the turbine to capture more energy then it would other wise be capable of. Dr. Kirke working on the Queensland Gold Coast Australia, formerly senior lecturer of Griffith Faculty of Engineering on the Gold Coast, collected data on several forms of combinations of shrouded turbine combinations. This was done by first testing a turbine in free stream and then encasing it in a duct. The duct was venturi shaped with a modified down stream wide angle outlet that encouraged flow to be drawn across the turbine as a result of a sub atmosphere of low pressure that occured behind the turbine. The resultant higher velocoty allowed the turbine to achieve thses results. Later in 2005 Kirke analysed results from a scaled up version of the same design confirming a 3 fold augmentation of flow and increase in power the turbine was capable of producing. The reports from thisand other work by Kirke is available upon request. (I just need someone to help me with the uploading) (Added by User talk:210.9.237.1 on 8 Aug)

This information is relevant, but probably not to the Tidal Power page. It is probably the case the the best location for this information is one of the following pages: Turbine, Water turbine, Wind turbine, Ducted fan, in particular Turbine#Types_of_turbines. Please read those, and links therein, and add this information in the most appropriate place, not forgetting to cite your references. Please note also that Wikipedia should not be used to place or promote original research - everything posted should be publicly available, and specific facts should be referenced (especially if they are new or controversial). Fig 11:00, 8 August 2007 (UTC)

By the way a ducted fan is NOT the same as a ducted turbine. You have confused the propeller and the turbine. Tidalenergy 00:46, 21 October 2007 (UTC)

Shrouded turbines have appllication in tidal stream so they should be granted space on the page, or else your bias on barrages is sustained. Shrouded turbines are the next progression in turbine development, there has really been no development since the middle ages, a propellor on a stick is still a propellor on a stick which ever way you look at it, so regardless of whether you believe they are a figment of my imagination or not they are out there in us and gaining in popularity where barrages can not go. The fact remains that shrouds cause greater capture then an open turbine and can even be used in barrages or tidal fences to increase the effriciency of the turbine. Had you not remove the link to Kirke and had actually read it you would have learned of their commercialisation in recent times. They talk around the traps is that they will make all else obsolete. Seems your opiniond about it being my opinion are wrong. Sorry! Tidalenergy 00:04, 12 August 2007 (UTC)

Response. As a shrouded turbine is a technology that has been developed for tidal sites it does have relevance. The information available is NOT origional research and is available. Had you not removed my edits the information would have been available for all to see. Tidalenergy 02:51, 9 August 2007 (UTC)

The comments about shrouded turbines (including in the energy calculations section) are clearly commercially motivated as the contributor continually removes an important qualification: if you compare the size of the rotors between shrouded and 'open flow' then the shrouded ones will generate more electricity. However, this is disingenuous, as if you compare the diameter of the area swept by the open flow rotors with the diameter of the mouth of the shroud then the energy is similar. The question of efficiency is then a matter of whether it is more efficient to increaste the size of the rotors, or to encase them in a shroud. —Preceding unsigned comment added by 217.155.47.110 (talk) 09:59, 4 September 2007 (UTC)

Well may you say disingenusous, but you are still wrong in your assumption and the article by Kirke that I have posted below on "Developments in Ducted Water Turbines" cites many references to prove that you are indeed mistaken. The turbine in the wide angled down stream (duct) shroud does NOT capture the same amount of flow as the opening of the shroud. If you look at the CFD Jpeg you will see that the flow lines clearly indicate that the flow bends from outside the line of the inlet and is drawn in from a greater flow then the size of the inlet. So a turbine in the shroud is in effect able to harvest 3-4 times as much flow then if it were minus the shroud. Put another way a turbine in open flow would need to be 3-4 times larger then the turbine in the shroud to produce the same amount of energy. The shrouded turbine does this due to the way the shroud sets up a sub atmosphere of low pressure behind the turbine; it litterally sucks flow into the shroud, across the turbine. The flow is drawn in from a greater area then the shroud inlet, up 3-4 times. Look at the flow lines and the colour contours and see for yourself.

Actually though, you get the same effect of sucking in extra flow even without the shroud. —Preceding unsigned comment added by 83.105.57.47 (talk) 12:22, 2 October 2007 (UTC)

The commercial facts of life are that if you wish to invest in a business that has open stream technology, then you may well wish to invest in tidal stream shroud technology as it will return more on your investment. This may not be to the liking of some but in the real world the dollar often rules the decision as to whether a project would go ahead or not. For example the stalled Severn Barrage is unlike IMHO to ever proceed as it would more then liklely become a white elephant that would send investors broke. This is why investment has been flooding into tidal stream technology with hundreds of potential sites and dozens of commercial pilots commencing around the world. Commerce is a fact of life. So I am sorry you feel the way you do about the topic.Tidalenergy 03:39, 26 September 2007 (UTC)

Also the "energy calculation section" that you criticise is the correct scientific maths formula for calculating energy from a turbine designed to extract energy from tidal stream. It may not be to your liking but that is correct and that is that. It is not a good idea to go change things because they do not agree with your way of thinking. It is just mot right to do so. If you struggle with the concept and would argue that it is commercially motivated go to the scientific community and argue with them as they are the ones who developed the formulas over long years to provided engineers with the tools to aid human kind. If you can get the science community to change their minds I will be the first to pat you on the back.Tidalenergy 03:41, 26 September 2007 (UTC)

Does the shroud have to be circular as a rotor does, or can it be shaped to fit the available space? —Preceding unsigned comment added by Tabby (talk • contribs) 21:21, 15 September 2007 (UTC)

That's a complex question: on the one hand, the shrouds needs to maintain a venturi shape (otherwise there is no point), on the other hand, some modifications may be possible and clearly the shroud joins the seabed in a non-circular shape. I'm sure Tidalenergy can provide a large amount of text on this. Fig 10:28, 16 September 2007 (UTC)

Thank you Fig....The shroud does indeed need to mainatain a strict geometry or else the ventuir property fails. That said the shroud can be round or multi sided. Tidalenergy 08:06, 23 September 2007 (UTC)

CFD graphic added to the Shrouded Turbine article

Thank you for assisting in uploading the CFD graphic of the shrouded turbine in operation. I have added a brief explaination that it is my sincere hope will put an end to the constant warring about the subject as it clearly shows haw the shrouded turbine is not subject to the Betz limit. I would welcome any assistance with my poor grammar in the article. Enjoy Tidalenergy 22:33, 14 September 2007 (UTC)

Tidalenergy, thanks for adding the graphic and extra information as requested, it makes things clearer for the reader. However, you have still not addressed the fundamental issue regarding a claim of efficiency of "3 times higher then the Betz Limit of 59.3%". Noone here has contested that a shroud can lead to 3-4 times higher energy extraction than a similar sized turbine. The problem I still have is that you are using the word efficiency and implying 180% efficiency - a value over 100%. As I'm sure you know, energy efficiency can never go over 100%, see energy conversion efficiency for exactly why. If you replace the words efficiency with energy extraction I will be happy. Fig 10:34, 15 September 2007 (UTC)

Fig, I can see why you have difficulties with accepting efficiencies of over 100%, but this sort of description is not uncommon in scientific circles. The efficiency of a turbine is usually described in terms of its normal area. If one can contrive to increase the local flow so that the output is higher, then it is natural to use the same denominator (the area of the turbine) in calculating the efficiency in order to make comparisons. There are clearly extra costs involving the shroud, or duct, but these are not part of this particular measure. It is not claiming an energy conversion figure of greater than 100% as far as I can see, which would clearly be impossible. Chris55 21:26, 15 September 2007 (UTC)

I accept that, my point is that the text as it was implied the latter. Fig 10:29, 16 September 2007 (UTC)

It is not implied --- this is the way it is described both in the scientific circles and in the engineering community. What would you have the entire world change their way of speaking cause you can't agree with their terms? Tidalenergy 03:58, 18 September 2007 (UTC)

Energy is not exceeding 100%. You have misunderstood. Lets say a free stream turbine is in a flow that is 100m wide and 10m deep with the flow at 1m/s --- we therfore have 1,000 cubic meters per second of flow. This is 100% of the flow. If the turbine above has a sweep area of 10 square meters it would be harvesting 10 cubic meters per secong of flow --- or around 1% of the entire flow. If the same turbine were placed in a shroud of suitable geometry able to augment the flow then the turbine would have 3-4 times the flow availabe to it compared to the free stream example --- or about 3-4% of the entire flow. If this make sense.

You must compare the turbines to themselves and have them in free stream not in an enclose system or a pumped or pressure facility. Otherwise you have missed the point about the Betz Limit not applying.

In actual life the free stream flow where turbines are loacted is vastly greater so the example above is a little bit lame as an example - but still true. You must consider that the energy available to the turbine is not 100% of the flow, only what the sweep area of the turbine is capable of harvesting. It is obvious then that the efficiency of the turbine and therefore energy produced can be increased to 3-4 times by placing the turbine in a shroud. This increases the turbine effiency by 3-4 times so 100% never enters the equation. Tidalenergy 00:58, 17 September 2007 (UTC)

Efficiency >100%?

"Turbines are able to be powered in reverse by excess energy in the grid to increase the water level in the basin at high tide (for ebb generation). This energy is more than returned during generation, because power output is strongly related to the head."

Either someone is confused about efficiency or the above is just unclear. It _looks_ like it implies an over unity device, and while I appreciate it probably doesnt mean that, it doesnt explain and isnt clear.

The need is to explain it clearly.

You are right, that is also unclear. More extra energy is extracted than the pumping used because while the pumping is going on, the tide turns - so the head grows (as the height difference between the two sea levels increases) much faster than would be from the pumping alone. Fig 10:33, 16 September 2007 (UTC)

I think the way to explain this is to look at high tide, say at 10 feet, and to say that you pump water from sea level (10 feet) to 2 feet above sea level (12 feet). If you then wait for the sea outside to go back to zero feet before you open the pumps, you now have a head difference of 12 feet. So the cost of pumping water up 2 feet at high tide, is more than returned by having trapped a later of water (2 feet thick) which is now suspended between 10 and 12 feet above sea-level. That is, if I understand it correctly. The article should be changed to explain this; as it is misleading. The previous explanation does not explain things. Adding pumping plus tide, simply equals tide without pumping, plus the pumping. i.e. no synergistic effect. In fact, if you pump fast enough at low tide, all you are doing is replacing tidal power with electrical power, which is a waste. The timing of the pumping to the peak of the tide is critical. —Preceding unsigned comment added by 83.147.139.15 (talk) 15:01, 17 September 2007 (UTC)

This above is a stored capacity and not a free stream technology. There are two types of systems that are being confused. The first is a pressure head -- that of a column of water being held behind a dam or barrage. The greater the column of water the greater the pressure and therefore the greater the amount of energy available.

The other is a velocity head where a turbine is in free stream similar to an underwater wind mill. (I put an explaination of underwater windmills on the article page but some budding astro physicist in their immense wisdom deleted it) As the water velocity increases so to does the energy available. As the water flows faster the energy increases. See the energy calc' on the article page that shows as the velocity doubles the velocity head goes up 8 times. (V x V x V = velocity cubed -- so sorry but I don't yet know how to upload formulas)

Finally the one that every body is debating and struggling with is the shrouded or ducted turbine that operates linke a venturi. (Again a Stephen Hawkins wannabe took off my discussion about Benoulli and venturi's) The turbine is in free stream, only it is enclosed in a duct or shroud that increases the free stream flow velocity across the turbine due to a vortex created by the shroud downstream-behind the turbine. As the turbine is enclosed in a shroud the increase in velocity is available to be recovered. The shroud accelerates the free stream velocity, typically 3-4 times (see Kirke above) allowing the turbine to produce 3-4 times the power due to the 3-4 times increase in velocity. It is really that simple. There is no black magic, it is just that the shroud increases the velocity across the turbine that then increases the turbine output power --- typically 3-4 times. This is how a shrouded turbine can exceed the Betz Limit. There is no 100% factor comes into it.

I have struggled to make it clear. Maybe if you think of pressure head as a dam and velocity head as a windmill it may help. I am a bit lost as to how many different ways one can explain the same principle.

AND please don't stumble over the math about 8 times --- it is the Velocity cubed relationship in the equation. The reason why barrages are obsolete. A 2 meter per second flow is the equivalent in velocity head energy as an 8 meter high tide. In the equation where V x V x V occurs substitute the number 2 and the results is 8. So flow of velocity of 2m/s = 8 meters of velocity head. 2m/s is about as fast as grandma walks and is quite common globally, so imagine if you had a velocity head of say 4m/s (less common but many hundreds of sites globally) it would equal 64 meters of velocity head, or about as high as some of the highest hydro dams in the world. There are very few sites globally with 8 meter high tidal ranges but thousands of sites globally where 2m/s of flow velocity occur. Another reason why the table about schemes under consideration on the article page needs deletion or very strong revision as it is misleading. (I also made a start of a study of the table but someone FIGured it was not worth keeping and removed it.

Commercial interests are zeroing in on the sites where these sorts of high flows occur as holding great returns for renewable energy development. Rather then spend billions on the pie in the sky Severn Barrage, why not put an array of tidal turbines on the sea bed, allow enough room for shipping to pass over head like they are doing in the East River in New York, and utilize the high current or velocity head to produce energy at a fraction of the cost. Go one step further and add a duct or shroud to the turbines and increase the velocity across the turbine 3-4 times along with the power output and then you really have a rewnewable energy resource for an energy starved planet. Yippeeeee! Tidalenergy 03:43, 18 September 2007 (UTC)

That isnt possible. Again more clarity needed, both in understanding and explanation.

I'll see what I can do. Tabby 21:33, 15 September 2007 (UTC)

I think your edits do the trick Tabby. Fig 10:33, 16 September 2007 (UTC)

You guys are comparing apples to oranges. In so far as shrouded or ducted turbines are concerned they operate under a different set of rules. They can achieve what to some is a theoretical impossibility that of exceeding the Betz limit by 3-4 times. Only they are not working in a closed environment or a stored facility --- they are in free stream. AND they achieve these results by creating a down stream vortex behind the turbine as seen in the CFD. If you try to compare a pressure turbine or a barrage turbine then you have fallen into the trap of not understanding the argument of why Betz does not apply.

Maybe you guys would see the example of comparing a propeller engine plane to a jet engine plane. The propeller driven plane can not exceed the sound barrier but the jet can. So to the ducted turbine sucks flow into the duct concentrating the energy and instead of forcing it out the back in the form of thrust converts the concentrated flow into shaft power that can do work. It does this at a higher efficiency then if the same turbine were to be placed in free stream minus the duct or shroud.

You guys are hung up on a problem that is so simple once you open your eyes to the fact that the Betz limit does not apply to shrouds in exactly the same way as the speed of sound does not apply to jet propulsion engines. You can not compare them as they are not the same and operate under different principles and have different properties. Tidalenergy 00:44, 17 September 2007 (UTC)

Wave energy turbine reference deleted

The tidal stream turbine is NOT a wave turbine. There are some stark differences. A wave turbine is operated by compressing air in a tube or tunnel. Some have oscilliating blades like the one in Port Kembla Australia. (See Energetec ???) while a free stream tidal turbine is eithe a cross flow turbine (See Darrieus) or an axial turbine. (See propeller on a stick - ha!) I am unaware of any site in the world that calls it's tidal stream turbines wave turbines. Sorry to put such a fine point on it. Tidalenergy 04:03, 18 September 2007 (UTC)

Manners in the debate on this page

There is very little manner on this talk page, in particulr discussion here would be much better if "Tidalenergy" restrained from personally insulting anyone who disagrees with him. 80.247.80.248 16:10, 18 September 2007 (UTC)

Sorry I will try to refrain from insults. But if you walked a mile in my shoes the last couple of months you may be a little angry too! It might be a good idea to NAME a certain other person for similar comments. Truly my patience is a little thin here as I have been wrongfully blocked (twice) and had individuals solicit others to harang me and falsify and make misleading reports and complaints on various pages including COI. All because I have tried to bring this article into the present. Seems like there are less noble agendas. Nevertheless I will take your chide and refrain from further comments of this nature. Thank you for up holding the standard. Onya !!! Tidalenergy 11:52, 19 September 2007 (UTC)

Shroud disadvantages re edited

The edit about the disadvantages of the shroud were misleading and not fully thought through so I redited them to properly reflect the ture nature of the commercial technologies out there. The same disadvantages include open or free stream so maybe they need to be included. I had a go at it but maybe someone can do better???

Shrouds are able to be yawled to work in any direction or flood and ebb tide, even open ocean. Placed on a turn table they orient up stream at all times a the balance point is in front of the meta centre. Just as a wind sock always point up stream so to a shrouded turbine can face upstream. Or it can be placed under a pontoon where in clement surface conditions do not occur. This way it can swing like a boat on a mooring in a saway and always face up stream. Of course this does not apply to run of river. As this is not a disadvantage I left any edit about run of river for another heading.

Shrouds can be raised and lowered. They have been doing so in Canada and Australia. As the overall size of the unit is smaller for the same amount of power compared to free stream open turbines it can be handled more easily. So this is not an issue so I changed it so it was not misleading. But congrat's to the editor for thinking. Shows some deep contemplation of all the issues even if the brainstorm was wrong. Keep them up.

The edit about tidal ranges was not accurate also. Tidal stream turbines whether open or shrouded are typically not placed where they would be out of the water at low tide. To do so would be commercially quite foolish. In any event the fast flowing regions where these technologies are located are usually quite deep having been jet balsted by water for millenium. They are underwater and free from and flotsam or jetsam that may damage the rurbine and or shroud. I have a recent paper (thesis) that is probably the best example of a monopile placed on the sea bed if anyone is interested. The shroud sits on turntable and monopile allowing the turbine to yawl or pivot about the central axis. It is very clever and worth viewing.

Finally the loads need to be considered and while the loads are greater spread sheets I have seen (ask your nearest commercial company if they have a prospectus) on tidal stream shrouds shows that the cost of engineering for these loads is minimal in the overall installation. Tjhis is because the turbine needs to be restrained, if the restraints are streamlined to form a shroud then there is a huge net benefit to commercial bottom line. Tidalenergy 12:08, 19 September 2007 (UTC)

The point added about pivot/turntable attachment placing limits on the size and robustness of the shroud and turbine is both fair and valid (most especially if the shroud is also able to be raised out of the water!), but you have deleted it. Please put it back in, in some form. If you cant bear to do that then I will do it. Also, it is not true that all stream designs are mono-directional - anything based on a vertical-axis turbine will be omni-directional. Please adjust that also. Fig 19:43, 20 September 2007 (UTC)

Good point -- an old saying says iron sharpens iron. I enjoy your input! I admit I did not think mabout VAWT's vertical axis wind/water turbines) and concede that they are multi directional. In my defence I was thinking about axial turbines (propeller on a stick type). I would also add several more caveats subject to your approval (here first?) I need a bit of time so if you wuldn't mind indulging me I will do both --- re edit the lines you mentioned and follow it up with some additional advantages and disadvantages as there is some exciting word coming out of Canada where they have 16 knot (8m/s) flows. Is this acceptable to you? 210.9.237.1 09:53, 22 September 2007 (UTC)

Yep, that's fine... Fig 11:22, 22 September 2007 (UTC)

Kirke Developments in Ducted Water Turbines

I changed the reference to Kirke's report that it was his thesis. It was not his thesis, it was an article he published some 10 years after his PhD thesis. Tidalenergy 08:20, 23 September 2007 (UTC)

3 commercial barrages reverted

I have reverted the discussion above on barrages as it sustains the debate that there are only 3 barrages in the world. AND they are commercially run.

There seems to be a bias away from the more common tidal stream technology and toward the less environmentally friendly, visually intrusive and extremely expensive barrages.

The saying that "barrages are obsolete" is sustained by the fact that there is little likely hood there will ever be another tidal barrage built anywhere in the world (this includes the Severn Barrage) yet the number of tidal stream technologies grows by the day.

The article page should reflect these facts and remove barrage technologies from the head of the list down the page where it belongs and move tidal stream technology up the page to more accurately represent the trend in the technology.

Otherwise it is misleading. Tidalenergy 03:17, 26 September 2007 (UTC)

Shrouded Turbine Geometry Developments

A shroud or duct housing a turbine that increases flow across the turbine roughly resembles a venturi. There is quite some material on variouis pages about venturi's and the Benoulli effect (pronounced In am reliably informed by my French friend Ben-oo-ee). Benoulli found that an increase in flow Velocity corresponded to a proportional decrease in Pressure. So a shroud or duct can operate on this principle. A suitably designed shroud causes an increas in velocity through the shroud and across the turbine by creating a low pressure in the shroud down stream-behind the turbine. As to what the the ratio of the turbine to shroud would be is best described by using the CFD graphic attached to the article on the main page here.

It is clear from this particular CFD graphic that the ratio of the shroud to turbine varies from only slightly larger up stream to almost exactly the size of the turbine at the throat to vastly wider down stream of the turbine. These have been called wide angle down stream shrouds or ducts. However not all shrouds are the same and some are more efficient then others. The one in the CFD posted on the main page looks like it is one that works particulary well. It has a 3-4 fold increase in flow velocity in the throat of the shroud where the turbine would be located (the turbine is not shown). Tidal Energy Pty Ltd claim to have eclipsed the world record if not world best result achieving 3.84 times in early development. Many companies have touted increases in power output by using a shroud. Blue Energy for example quoted 5.5 times in the early 1990's but has not Patented anything nor published any literature that I am aware of.

There is however an abundence of Patents filed with various patent offices globally. Perhaps a search of the US Patents Office might provide some answers to questions as to what these ratios might be.

At the risk of being indulgent it is fair to say in a similar way that the jet engine allowed the aerospace industry to exceed the theoritical limit of the speed of sound in the 1940's with various designs of engine, that emergence of shrouded turbines has potential to exceed the Betz Limit allowing more energy production then would otherwise be possible from a free stream turbine of similar size. Tidalenergy 21:20, 27 September 2007 (UTC)

Reorganisation and talk page archives

We were doing so well, but it would last would it. I have reverted Tidalenergy's re-organisation that he was pushing some months ago, but for which there was no consensus.

There was indeed consensus but was removed because it did not agree with your opinion For example the question about three only being thre barrages globally and all of them being commercial was removed. This proved you were mistaken.

You go on to say that there is no consensus. How can there be any consensus when large amounts of edits on tidal stream are removed. This is not consensus by censur and needs to stop.

I have also reverted all the material that he moved from the talk archive page back to this main page.

Tidalenergy, please don't move material from the talk archive (where it is safe and can still be accessed) back to the main page, this defeats the who point of archiving. Also, please don't think that just because things have been quiet for a while you can simply attempt to force through controversial edits while people aren't looking. Cheers. Fig 08:32, 1 October 2007 (UTC)

You have been asked to provide information on why barrages are not obsolete but have failed to dos so.

My point in re-editing the main page is that your opiion has not been sustained with any scientific fact. You have been proven wrong time and again and your bias for barrages with only three in the world proven.

You have penchant for the Severn Barrage that has obviously overflowed here.

You failed to respond to the edit on this page about barrages their number and their commercial nature.

By your silence you affirm that barrages are obsolete. I note that the evidence I posted here about barrages being obsolete is removed every time I place it here

• You have failed to sustain the debate over shrouded turbines not being subject to the BETZ Rule.

• You have failed to sustain debate over tidal stream being the dominant technology.

• You failed to sustain the debate over a 3 fold augmentation using a shroud or duct.

• You have removed large amounts of relevent data on cost and commercial returns.

• You have not been able to provide the citations for the barrage section.

• Finally you have taken valuable information off the main page in a wholesale attack on the dissemination of facts.

What exactly are you objecting to??? Tidalenergy 09:51, 1 October 2007 (UTC)

Barrages and "unverified material should be removed?".

The vast amount on barrages as a dominant technology worthy of top billing on the main page needs to be addressed. So far no one has provided any evidence as requested. Material on tidal stream placed here on this page has been deleted time and again in order to prevent any debate. When to main page was redited to properly reflect the true nature of the technologies and their importance the FIG reverted the edits. FIG's anarchy has over ridden debate and discussion here. When questions have been answered proving FIG wrong they mysteriously disappear.

This is censur of the debate and must stop.

I would urge those with the power to remonstrate with FIG so that his bias for barrages does not over ride the full and frank discussion and dissemenation of facts. Tidalenergy 09:36, 1 October 2007 (UTC)

Three new headings deleted by FIG - WHY?

The following was palced on the main page and removed by FIG. It is important information about the commercial nature and revenues from tidal stream technology that is important to an informed and factual main page.

I would like to know what exactly is being objected to and worthy to be deleted by FIG.

You know full well that they were deleted because you deliberately put them into a huge sequence of edits that re-organised the page in a way that you KNEW was controversial and that you KNEW there was no consensus for. Fig 08:42, 2 October 2007 (UTC)

Gee I would love to have your crystal ball. In point of actual fact I did not place it there to cause controversy. These are relevant to the technology and to the industry. On your Severn Barrage page you discuss prices and the various twists and turns of the game. Here I have put the facts out there. In one easy to follow calculator students, the family man or an investor can do the sums for themsevles. Perhaps you should take a leaf from this page and present the evidence about the Severn Barrage for scrutiny that you claim to have but because of some technical reason are unable to lift. Seems like you want to have everyone believe you because of 1,000's of edits whereas the next guy is supposed to provide all the facts. A double standard exists here. To sustain a point in the debate you must produce the evidence not throw stones from the side lines. Please if you feel aggrieved produce the evidence to gain say what is being put up -- put up or shut up as the syaing goes. Sorry but it needed to be said.

In any event who made you god over the page to take hours of very precise hard work and to trash it without so much as a by your leave. Where is the consenus in that? Did you ask? Did you seek any debate. Really now, a case of the pot calling the kettle balck. Just because the farmer had never seen a giraffe doesn't mean they don't exist. So too, just because YOU have never seen this. The math is correct isn't it? The explainations are relevent arn't they? Just what exactly is so objectional? Or is it a case that you would prefer no one knows? Just what exactly is so objectional, please say it here for all to see and be enlightened?

I note that you love to pull down, detract and demolish (which is always easier). You claim to have 1000's of edit under your belt. Why not offer something constructive here instead of pointing the finger? I also note that your style is to avoid a debate (see below) when you have been exposed for bias. My comments below remain unanswered by you, just like the ones on the 3 barrages globally. How about making an answer instead of whining about it? You can not have it both ways. Either your barrages are oboslete or they are not -- either tidal stream is the dominant technology or it is not, that is the question. Tidalenergy 21:14, 3 October 2007 (UTC)

Commercial Calculator

Prices paid for electricity varies around the globe. The kilowatt price can vary from 10-15 British Pence in the UK to 30-40 US cents to 50-60 US cents or more if the area is remote and electricity supplies come from diesel generators.

The following equation can be used to calculate the revenue from a tidal stream turbine. By substituting variables such as size of the turbine, flow velocity and price into the equation it is possible to accurately predict an annual return.

Keeping in mind this equation does not include the cost of civil infrastructure which would vary with manufacturer and from site to site.

In order to calculate the revenue that a tidal stream generator would return the following equation can be used as a guide. Assuming 1000 meters of cabling then the following would be a close approximation.

Annual Revenue = Cp x 0.5 x ρ x A x V³ x Hr x LL x GGL x $ x Y (x 3 for shrouded turbines)

Where: Cp = the turbine coefficient of performance (say 20% for free stream or 60% for shrouded) ρ = the density of the water (seawater is 1025 kg/m³ or 998 kg/m³ for fresh water) A = the sweep area of the turbine (in m²) V³ = the velocity of the flow cubed (i.e. V x V x V) Hr = the number of hours per day that the turbine would operate at maximum efficiency (12-22 hours for tidal and 24 for run of river) LL* = x .95 line losses (multiply by .95 )assuming a 5% loss in a cable run of 1000 meters Gearbox and Generator Losses* = x .95 (multiply by .95) assuming 5% for gearbox and generator losses $ = insert the price per kilowatt that would be paid (prices vary with location) Year = 350 days (allowing 15 days per year for servicing cleaning etc if necessary) Shrouded turbine = 3 times (augementation factor of the shroud)

May vary from manufacturers. For example a tidal stream turbine with a sweep area of 1m² at a site with a 3m/s flow velocity operating at peak/maximum for 12 hours earning 10 cents per kilowatt would be,

Annual Revenue = Cp x 0.5 x ρ x A x V³ x Hr x LL x GGL x $ x Y(x 3 for shrouded turbines)

Annual Revenue = 0.20 x 0.5 x 1025 x V³ x 12 x 0.95 x 0.95 x 0.10 x 350 (x 3 for shrouded turbines)

Revenue Revenue = $10,490.20 ($31,470.62 for shrouded turbines)

Keeping in mind this is only a 1m² sized turbine in 3m/s flow velocity for only 12 hours per day. Many commercial turbines are 20-30 times or greater in size in faster flow velocity at 20 or more hours per day. Run of river turbine would operate for 24 hours per day.

From the above equation it can be demonstrated that the predictability of tidal power holds very great potential and interest for renewable investment dollars. Wind and solar are unpredictable by nature but tidal stream can be predicted years in advance allowing businesses to plan years in advance.

As the flow velocity doubles the the Velocity term in the equations causes the increase 8 times.

i.e. 2 x 2 x 2 = 8 and 4 x 4 x 4 = 64.

So to the revenue from the turbine increases 8 fold when the flow velocity doubles. The same turbine given in the example above if installed in a 6m/s velocity would return 8 times or $83,920 (or $251,760 for a shrouded turbine) from every square meter of sweep area of the turbine.

This becomes a compelling argument for the commercialisation of tidal stream technologies.

High Velocity Sites a Commodity

As mentioned above, "a factor in human settlement geography is water. Human settlements have often started around bays rivers and lakes. Future settlement may one day be concentrated around moving water, allowing communities to power themselves with non-polluting energy from moving water".

Sites with high tidal stream velocities are becoming a highly sought after commodity when selcetion of a tidal stream site is under consideration. In some instances Government Entities in North America [citation needed] have begun legislating to prevent a gold rush mentality with unscrupulous entrepreneurs with no access to technology speculating and claim jumping sites.

Variable Output and Value Adding of Energy

Tidal power schemes do not produce energy all day. A conventional design, in any mode of operation, would produce power for 6 to 10 hours per flood and ebb tide or 12-20 hours in every 24 hour period depending on the site.

As the tidal cycle is based on the rotation of the Earth with respect to the moon (24.8 hours), and and an 18.6 year epoch cycle, electricity demand would not always coincide with supply. However, the tides are relatively reliable and more predictable than other alternative energy sources, such as wind.

Tidal stream turbines deployed in run of rivers location are not subject to tidal cycles and can produce energy 24 hour a day. Deployed from the banks of rivers close to the end user/s they avoid many complex issues of a salt water marine environment.

Value adding the electricity produced is one method of using energy produced without the limitations. For example high quality potable water can be produced from using energy to power reverse osmosis plant. As water is easily stored it matters little if a the tide is flowing at 3 am when a load on a grid is less.

Water is a high value commodity that can exceed that of fossil fuels. In Australia the petroleum industry is worth AU$250 million annually where as the bottled water market is AU$350 and growing rapidly.

Hydrogen can also be produced from the electrolysis of water and electricity from tidal stream generators. Hydrogen has been used to supply the buses in German cities for 30 or more years and is perdicted to become the replacement to fossil fuels as hydrogen is virtually unpolluting.

I have had enough...

OK guys, this is it. In the several years that I have been editing Wikipedia to rack up nearly 1000 edits I have never been chased from a page, but Tidalenergy has managed it. I am absolutely sick to death of the endless abuse and rudeness; I am tired of endlessly trying to maintain sanity and partiality on a page against someone who is clearly on an obsessive mission to promote his former company's commercial products. I have had enough of wading through pages and pages of spurious rantings and verbiage on talk pages.

Tidalenergy, as you well know, there was no consensus for your re-ordering of the article a couple of months ago, nor was there agreement with your OPINION that barrages are obsolete. The UK government clearly doesn't agree with you, because it is about to spend many millions of pounds investigating the Severn barrage [1] - much more money than your company Tidal Energy Inc [2] managed to secure while you were working for it. (I note your Wikipedia advert page at Editing Tidal Energy Pty Ltd was recently deleted, even though I didn't know about it no doubt you will hound me for "victimising you"). Nor does the UK's Sustainable Development Commission agree with you, because yesterday it backed the proposal [3]. Tidal stream is simply NOT the dominant technology at the moment, and most certainly not the "shrouded turbine" variety which are hardly known, despite your commercial interest in wanting to promote it as such.

However, I no longer care. Unlike you I don't have a business interest or an ideological mission regarding the information on this page. I just wanted the world to know what the actual situation was. I will continue to edit other pages where, hopefully, there aren't people like you.

Good luck to the other editors here who have to try an keep this page NPOV - you have your work cut out for you. Signing off from this area... Fig 09:03, 2 October 2007 (UTC)

Sounds like sour grapes to me.

But then I asked why so I guess I had it coming. However you are all over the shop with your comments above.

Taking your point one at a time --- with over 1000 edits you have it over me. You have misused your vast experience to dominate this page with your penchant for a technology that has three barrages globally. IF the UK Government ever finds the 15 billion pounds to build the Severn Barrage, AND, the EPA ever lets the project go ahead then there will still be four; F-O-U-R in the entire world whereas the are dozens of tidal stream technologies commercially deployed globally, AND, their number grows every day due to their cost efficiency and low impact on the marine and built environment. Get a grip man you have thrown your weight behind a technology that is obsolete and you refuse to admit it. Being blind you refuse to see. That's the facts proven here before all.

You seem unable to make up your mind. On this page you say the Government will fund a project investigation yet your comments on the Severn Barrage discussion state "Ullman is also in error to claim that the barrage would be taxpayer funded. It would be funded privately in exactly the same way as lagoons would be". Hmmmmm. Which are we to believe? Exactly who is this? Don't you think any credibility you have flies out the window when you make comments like this taht are all over the shop? —Preceding unsigned comment added by Tidalenergy (talk • contribs) 05:38, 3 October 2007 (UTC)

As far the abuse and rudeness I would say you give at least as well as you got. Who reported me to COI and tried without success to solicit others to harangue me off Wiki? Who had me blocked? This behaviour is nothing short of anarchy by you. Why!? All because someone has proven a contrary view and has sustained the debate against your misguided opinion. Sorry old man but it needs to be said you are out of step with both the science and the technology. So we would be even on that score. I don't hold a grudge for you blocking me so I would expect the same from you. How about it?

As far as your sanity I am no expert. But I took a break and came back fresh after you had me blocked. It gave me new vigour and allowed me to re enter the debate. Maybe you should do the same!

On obsessive; that is your opinion. I would say passionate is a better description.

Your allegations of my commercial interests I have answered on every occasion. Sorry but you are mistaken. Believe it or not? In any event you squeal about commercial technology on Wiki yet turn a blind eye to your pet barrages being commercial. Seems like hypocrisy to me. How can references to commercially run barrages be allowed while commercially run tidal stream technology is deleted. This is pure biased censure.

Deleteing of the Tidal Energy Pty Ltd page is again a double standard and one that needs to be looked at. How come similar tidal stream companies like the UK's MCT and others can have their own page while others such as Tidal Energy Pty Ltd in Australia can not??? Seems to me like there is a double standard. Look down the list of companies on the main page and see for yourself how many have their own main page.

As for the UK government we will have to wait and see if the environmental reports come back with a thumbs up. From looking at other similar proposals around the world they have all failed on environmental grounds due to massive alterations to the eco system affecting fish and marine birds etc etc. One thing the UK doesn’t need is their already dwindling fish reserves to take another body blow. Then there is transport. Who in their right mind would cut arguably one of the busiest waterways in the world and block sea traffic with locks and weirs? Finally the cost of 15 billion dollars is an outrage when it can be done cheaper with MCT turbines or better still, shrouded turbines. You are hell bent on pushing a technology that any government investor in their right mind would never support. But you don't care you will keep putting down anyone who disagrees. You can take a horse to water but can't make it drink seems to ring true here. You have made up your mind and refuse to let the facts convince you otherwise.

Tidal stream IS dominant with many more installations globally then the 3 barrages you love. You refuse to receive the conviction and continue to harrass me over this point. When you said the 3 barrages were not commercial I posted the names of the commercial entities here and you deleted it as it shamed you in the debate. You then went about smearing me over shrouded turbines. The fact remains that they are the next generation of tidal stream not unlike the jet engine and the propeller. If there are more tidal stream technologies in use then logic would suggest that they are the dominant technology and receive top billing.

What nark's me is that I have tried to debate this with you based on the facts and the evidence I produced here everytime you asked it to be proven. However you have never answer my questions, you instead run for cover. This is not debating this is sniping. For this reason maybe you are better off leaving and not returning , who knows?

What your really are doing here is complaining that you have lost a debate and are bitter and twisted out of shape because of it. For this I am sorry as I would like to have kept your input on this page, perhaps even become friends (I did extend to you several times the hand of friendship but you never took it) as your are a fine editor and one I have grown to respect even though I did not always like you or agree with you. I would urge you to please, as a gentleman, take a break and come back fresh and ready to keep up the debate and the main page true to the principles of Wiki. Iron sharpens iron --- butter does not sharpen iron as the saying goes. Think about it. In any event go in peace, I respect your decision either way.Tidalenergy 00:54, 3 October 2007 (UTC)

Grammatical changes

I made changes to the grammar to the lead in statements as the grammar was poor. If anyone can improve on the existing edits please do so. Tidalenergy 23:02, 8 October 2007 (UTC)

Citations needed

I have no knowledge of tidal power, but frankly, this article is a mess. Aside from formatting issues, it's severely lacking in citations, and has quit a bit of unencyclopedic content. I don't intend to get pulled in to the arguments going on here, but just want to remind everyone that information on Wikipedia needs to have verifiable sources, regardless of what any editor knows to be true. That means that someone reading the article who has no clue about tidal power (like me) should be able to see where the information came from.

Anyway, while I can't help much on the information side, I'll see what I can do to bring the formatting up to Wikipedia standards. --NormalAsylum (t) 20:59, 24 October 2007 (UTC)

I'll put my hand up - I am relatively new and need help. I have asked several times to no avail. In regard to the citations, I also provide much information here but a dispute with another editor soured my passion after much was remove due to an allegation of COI. It seemd like a no win situation so I threw my hands in the air and walked. I am open for any offers of assistance re the citations. 210.9.237.1 07:20, 4 November 2007 (UTC)

CFD removed

I have been asked to remove the CFD. I had access to it to help resolve an issue/dispute here - now that that has been achieved it is no longer available to Wiki. 210.9.237.1 07:21, 4 November 2007 (UTC)

Citations needed

With one exception the citations requested for the price calculations have already been provided, i.e. the price paid for renewable energy in remote areas can cost US$0.50-60 cents per kilo watt as turbines are run on diesel power that is transported long distances to the remote locations. This is common knoweledge in the industry. The dilemna arises as to which remote location to choose. Does ones choose a location in remote Canada or Australia? As for the other citations they have already been provided in the text of the main page i.e the citation requested for price calculations is developed from the power equation above on the main page, so therefore the evidence has already been provided, the citation for the shrouded turbine has been provided many many times here on this discussion page and has caused a mini war between some editors - please read the "Developments in Ducted Turbines" by Kirke, the run of river citation seems to indicate a lack of understanding of tidal stream and run of river as tidal stream is exactly that, tidal stream, harnessing the flow of the flood and ebb tide, however, a run of river is a system that uses the natural flow of a river which flows constantly in one direction 24 hours a day - run of river is therefore self explainatory, the citation requested for the revenue increasing 8 times when the velocity doubles arise from the power calculation already provided above on the main page - as velocity doubles the power output increases 8 times due to the velocity cubed element in the equation for example 2 x 2 x 2 = 8 but 4 x 4 x 4 = 64 ..... simple maths - therefore the revenue which is directly proportional to the power, will increase 8 fold for every doubling of the velocity - all these have been provided.Tidalenergy 08:52, 15 November 2007 (UTC)

Source of Tidal Energy

I note that the opening paragraph currently states that the source of tidal energy is the Moon. This is not quite correct. The source of tidal energy is actually the rotational energy of the Earth. If the Earth did not rotate with respect to the Moon, lunar tides would still exist but they would be static and thus it would be impossible to extract energy from them. On the other hand if the Earth rotated but the Moon did not exist, there would still be (much smaller) solar tides from which energy could be extracted. Thus there is a very definite limit to the amount of energy that can be extracted from tides. While that limit is large, it is quantifiable. The supply is definitely not inexhaustible and extracting too much of it will, sooner or later, lead to undesirable side effects such as 25 hour days (or even longer). Of course this is also happening naturally as our tidal acceleration article explains. -- Derek Ross | Talk 05:42, 5 December 2007 (UTC)

This is an important point. Not that harnessing tidal power will have a noticeable effect on the length of the day (it won't within the next few million years), but that the tidal energy source is very limited in practice, not just in principle as for solar/wind/nuclear. Whereas the world's electricity production is, apparently, currently ~5TW, the tidal energy source is about 3.7 TW, only a small fraction of which will ever realistically be converted to electricity. (Increasing drag using turbines will probably not significantly affect the total source, but, counterintuitively, it's at least as likely to reduce it as increase it.) I would have thought a more accurate description of the energy source, together with a note about the potential contribution to global energy needs, should feature prominently. -- Kicocolm (talk) 11:28, 10 December 2007 (UTC)

Check through the history of discussion on this page. It was mentioned a few times but due to war between editors it was deleted by a person who believed their opinion on tidal barrages was pre-eminent. Please feel free to try again. 210.9.237.1 (talk) 05:19, 16 December 2007 (UTC)

There seems to be a misinterpretation, here and elsewhere at WikiPedia, on the consequences of 3.7 TW tidal dissipation (see the link above to Munk & Wunsch, 1999), which is mixed up with a 3.7 TW tidal energy source. This would only be true in case of an equilibrium between dissipation and propulsion, e.g. a car driving at constant speed with a motor compensating for the energy dissipation. Since the Earth's rotational energy is the source of the fluctuating tides, there is no equilibrium (other than the case when one Earth day has lengthened to 28 days). There is only a tiny tidal dissipation which "will have a noticeable effect in millions of years". So, it is clear that the mentioned 3.7 TW is only a fraction of the available amount of tidal energy (in the order of EW, 10¹⁸ Watt). Kraaiennest (talk) 23:45, 12 February 2008 (UTC)

I agree that the source of tidal energy is not the moon but the earth's rotation. Tides involve no transfer of energy, kinetic, potential, or otherwise, from the moon to the earth. The moon, through its gravity, simply provides a mechanism for this rotational energy to be used at the earth's surface. This section should be changed unless there is an objection. Rudkins 17:05, 12 February 2008 (UTC) —Preceding unsigned comment added by Rudkins (talk • contribs)

Lots of tidal stream designs appearing

Just a quick note to the FIG to say your prejudiced opinion about tidal stream not being as common as you claimed can be checked on the Tidal Power page. Seems like your Severn Barrage will never see the light of day given all the money being invested in tidal stream technologies around the globe. See for yourself how many are being commercialised AND see the shrouded designs that you claimed didn't work. Sorry to say I was right about that old man. Tidalenergy (talk) 04:17, 22 March 2008 (UTC)

Types of Tidal turbines reverted

There are a number of shrouded turbines emergeing that may or may not have significance in the industry that need to find a place on the main page. Removal of the comparisons and contrasts make the page poorer for the exercise and limits the value of information. 210.9.237.1 (talk) 00:44, 24 March 2008 (UTC)Ю

Talk Page Archive

Archive 2 has been created with a link at above right. It is an exact copy of the talk page as it was before this edit. Archive 3, when needed in the future, should be a new subpage (same as creating an article) titled "Talk:Tidal power/Archive3" and the link added to the template on this page's code. For further information on archiving see Wikipedia:How to archive a talk page. See also User:5Q5 for the used archiving procedure. Thank you. Crowsnest (talk) 11:41, 28 March 2008 (UTC)

Citations needed

With one exception the citations requested for the price calculations have already been provided, i.e. the price paid for renewable energy in remote areas can cost US$0.50-60 cents per kilo watt as turbines are run on diesel power that is transported long distances to the remote locations. This is common knoweledge in the industry. The dilemna arises as to which remote location to choose. Does ones choose a location in remote Canada or Australia? As for the other citations they have already been provided in the text of the main page i.e the citation requested for price calculations is developed from the power equation above on the main page, so therefore the evidence has already been provided, the citation for the shrouded turbine has been provided many many times here on this discussion page and has caused a mini war between some editors - please read the "Developments in Ducted Turbines" by Kirke, the run of river citation seems to indicate a lack of understanding of tidal stream and run of river as tidal stream is exactly that, tidal stream, harnessing the flow of the flood and ebb tide, however, a run of river is a system that uses the natural flow of a river which flows constantly in one direction 24 hours a day - run of river is therefore self explainatory, the citation requested for the revenue increasing 8 times when the velocity doubles arise from the power calculation already provided above on the main page - as velocity doubles the power output increases 8 times due to the velocity cubed element in the equation for example 2 x 2 x 2 = 8 but 4 x 4 x 4 = 64 ..... simple maths - therefore the revenue which is directly proportional to the power, will increase 8 fold for every doubling of the velocity - all these have been provided.Tidalenergy 08:52, 15 November 2007 (UTC)

Source of Tidal Energy

I note that the opening paragraph currently states that the source of tidal energy is the Moon. This is not quite correct. The source of tidal energy is actually the rotational energy of the Earth. If the Earth did not rotate with respect to the Moon, lunar tides would still exist but they would be static and thus it would be impossible to extract energy from them. On the other hand if the Earth rotated but the Moon did not exist, there would still be (much smaller) solar tides from which energy could be extracted. Thus there is a very definite limit to the amount of energy that can be extracted from tides. While that limit is large, it is quantifiable. The supply is definitely not inexhaustible and extracting too much of it will, sooner or later, lead to undesirable side effects such as 25 hour days (or even longer). Of course this is also happening naturally as our tidal acceleration article explains. -- Derek Ross | Talk 05:42, 5 December 2007 (UTC)

This is an important point. Not that harnessing tidal power will have a noticeable effect on the length of the day (it won't within the next few million years), but that the tidal energy source is very limited in practice, not just in principle as for solar/wind/nuclear. Whereas the world's electricity production is, apparently, currently ~5TW, the tidal energy source is about 3.7 TW, only a small fraction of which will ever realistically be converted to electricity. (Increasing drag using turbines will probably not significantly affect the total source, but, counterintuitively, it's at least as likely to reduce it as increase it.) I would have thought a more accurate description of the energy source, together with a note about the potential contribution to global energy needs, should feature prominently. -- Kicocolm (talk) 11:28, 10 December 2007 (UTC)

Check through the history of discussion on this page. It was mentioned a few times but due to war between editors it was deleted by a person who believed their opinion on tidal barrages was pre-eminent. Please feel free to try again. 210.9.237.1 (talk) 05:19, 16 December 2007 (UTC)

There seems to be a misinterpretation, here and elsewhere at WikiPedia, on the consequences of 3.7 TW tidal dissipation (see the link above to Munk & Wunsch, 1999), which is mixed up with a 3.7 TW tidal energy source. This would only be true in case of an equilibrium between dissipation and propulsion, e.g. a car driving at constant speed with a motor compensating for the energy dissipation. Since the Earth's rotational energy is the source of the fluctuating tides, there is no equilibrium (other than the case when one Earth day has lengthened to 28 days). There is only a tiny tidal dissipation which "will have a noticeable effect in millions of years". So, it is clear that the mentioned 3.7 TW is only a fraction of the available amount of tidal energy (in the order of EW, 10¹⁸ Watt). Kraaiennest (talk) 23:45, 12 February 2008 (UTC)

I agree that the source of tidal energy is not the moon but the earth's rotation. Tides involve no transfer of energy, kinetic, potential, or otherwise, from the moon to the earth. The moon, through its gravity, simply provides a mechanism for this rotational energy to be used at the earth's surface. This section should be changed unless there is an objection. Rudkins 17:05, 12 February 2008 (UTC) —Preceding unsigned comment added by Rudkins (talk • contribs)

Did anyone else object to the statement that nuclear energy is described only as fission ignoring fusion? 210.18.195.66 (talk) 03:54, 21 January 2009 (UTC)

Lots of tidal stream designs appearing

Just a quick note to the FIG to say your prejudiced opinion about tidal stream not being as common as you claimed can be checked on the Tidal Power page. Seems like your Severn Barrage will never see the light of day given all the money being invested in tidal stream technologies around the globe. See for yourself how many are being commercialised AND see the shrouded designs that you claimed didn't work. Sorry to say I was right about that old man. Tidalenergy (talk) 04:17, 22 March 2008 (UTC)

Types of Tidal turbines reverted

There are a number of shrouded turbines emergeing that may or may not have significance in the industry that need to find a place on the main page. Removal of the comparisons and contrasts make the page poorer for the exercise and limits the value of information. 210.9.237.1 (talk) 00:44, 24 March 2008 (UTC)Ю

Advantage and disadvantages of shrouded turbines

This section is very unclear to me and lacks citations.

Advantages

"• A shroud of suitable geometry can increase the flow velocity across the turbine by 3 to 4 times the open or free stream velocity allowing the turbine to produce 3 to 4 times the power than the same turbine without the shroud."

What would be a more helpful comparison is between the amount of energy produced from the swept area of the free stream turbine compared with the diameter of the mouth of the shroud.

• More power generated means greater returns on investment.

No it doesn't. And it only results in greater returns if it is at the same cost, including not only the cost of manufacture and installation, but also the opportunity cost - i.e. does it deplete the available resource by the same amount? These are big questions that are not answered in this article.

• The number of suitable sites is increased as sites formerly too slow for commercial development become viable.

This is a valid point, but it illustrates how the first point is misleading, as the shroud reduces the size of the turbine needed to generate the same power, but only by taking a large cross section of slow moving water and forcing it through a narrow gap, thus increasing the speed of the flow. (N.B. It is true that venturi shrouds drag water in from beyond the edges of the mouth of the duct, but it is important to note that free stream turbines actually have the same effect and also suck water in from outside the swept area of the rotors.)

• Where large cumbersome turbines are not suitable, smaller shrouded turbines can be sea-bed-mounted in shallow rivers and estuaries allowing safe navigation of the water ways. [19]

It is not clear here whether it is the whole structure that is smaller or just the rotors.

• Hidden in a shroud, a turbine is less likely to be damaged by floating debris.

Why would debris not be sucked into the shroud? And if it was, the rotors would be turning much faster, and wouldn’t they therefore be more likely to be damaged?

• Bio-fouling is also reduced as the turbine is shaded from natural light in shallow water.

This needs a reference. I don’t believe biofouling has been a problem in fast moving waters. Particularly when sacrificial anodes are used.

• The increased velocities through the turbine effectively water-blast the shroud throat and turbine clean as organisms are unable to attached at increased velocities. [24]

• Described as 'eco-benign', the slow r.p.m. of tidal stream turbines does not interfere with marine life or the environment and has little or no visual amenity impact.

This is not an advantage of a shroud, and indeed shrouded turbines have a higher r.p.m.

Disadvantages

• Most shrouded turbines are directional, although one exception is the version[25] off Southern Vancouver Island in British Columbia. One-direction fixed shrouds may not capture flow efficiently - in order for the shroud to produce maximum efficiency to use both flood and ebb tide they need to be yawed like a windmill on a pivot or turntable, or suspended under a pontoon on a marine swing mooring allowing the turbine to always face upstream like a wind sock.

Why can’t you just have rotor blades that pitch to face in the opposite direction?

217.155.47.110 (talk) 15:24, 20 August 2008 (UTC)newscotland

Tidal stream or barrages layout corrected

If the Tidal Stream is the first heading then the fist dot point should be Tidal Stream not the other way round. 210.9.237.1 (talk) 04:46, 28 March 2008 (UTC)

Extravagent Claims Misleading

SeaGen make the claim of the first commercial tidal stream turbine. This is far from the turth. There have been a number of grid connected tidal stream turbines long before SeaGen. Blue Energy for example did it way back when. Here attached is a quote an the link. Read the following for yourself and decide if the SeaGen article on the main page should be deleted as wrong and misleading!!!!

A contract was awarded to build a 20 kW Vertical Axis Hydro Turbine in early 1983 for installation in the Seaway of Cornwall in Ontario and to connect it to the Niagara Power Corporation grid. The site was not very suitable, as it was too shallow and had currents of insufficient velocity. Nevertheless, the unit performed quite well, producing up to 20 kW on the grid.

Here's the link to the entire article. http://www.bluenergy.com/davisTurbinesptypes.html

Seems to me like these guys are running amok here. Tidalenergy (talk) 22:34, 25 June 2008 (UTC)

Are you aware of independent reliable sources, see WP:SOURCES? Seagen is off course also missing reliable references, so the article has to be altered anyway with respect to this claim. — Crowsnest (talk) 11:35, 30 June 2008 (UTC)

WP:SOURCES states,

If no reliable, third-party sources can be found for an article topic, Wikipedia should not have an article on it.

Who then is authorised to amend the claim? Tidalenergy (talk) 22:39, 30 June 2008 (UTC)

The claim was already removed, see here. -- Crowsnest (talk) 09:40, 1 July 2008 (UTC)

Being grid connected is not the same as being commercial. A 20kw generator can only be commercial if it can be built and installed at a price that can be covered by the revenue from the electricity. SeaGen at 1.2MW is four times more powerful as any other tidal stream turbine in the world, and is the first model of a design that will be manufactured for large scale farms of up to a hundred turbines. A journal reference has been added to the claim. —Preceding unsigned comment added by Fundy (talk • contribs) 12:06, 9 July 2008 (UTC)

Since when does Wikipedia offer journalism in place of peer review? In any event seems like you are arguing semantics. Segen were not the first but would have people believe there are. And what difference does it make whether it is 20kW or 20MW as long as it is commercial. Seems like Segen would rewrite history if given half a chance. 202.169.182.10 (talk) 00:05, 14 July 2008 (UTC)

what journalism? - the reference is to a peer reviewed journal. As clearly explained by fundy above, it doesn't make any difference what the scale is, it is a question of whether it is commercially viable. As far as I am aware, all other tidal stream generators are prototypes, as in they are not the finished model that the company expects to market. As I understand it, SeagGen is. —Preceding unsigned comment added by 83.105.57.47 (talk • contribs) 13:26, 18 July 2008

The extravagent claim about the world first commercial tidal plant is on the photo of the SeaGen caption. The caption is misleading and needs to be changed. Tidalenergy (talk) 22:56, 27 July 2008 (UTC)

The caption is not misleading, and it includes a citation referencing a peer reviewed academic journal. —Preceding unsigned comment added by 84.235.129.94 (talk) 15:09, 30 July 2008 (UTC)

The Blue Concept

I don't have the time now for any serious editing, so I'll just drop this here: The Blue Concept (Google search). That's windmills under water, developed by the Norse enterprise Hammerfest Strøm. A huge advantage over real windmills is that the power suply is very predictable, which also means simpler designs with less maintenanace. And my gut feeling tells me that a denser material like water will have such a higher concentration of energy that that will more than compensate for the slower flow. So it seems there is no point in building windmills above water in coastal areas. In 2003, Hammerfest Strøm built a prototype with a capacity of 300 kW in a sea strait near Kvalsundet. That's one mill, I understand. This will be expanded to 20 mills. These Tidal Stream Turbines are weighted down with 200,000 kg. Repairs are done with a floating dock that can lift the whole thing (excluding the weights, I presume). Hammerfest Strøm researches the effect on marine life in conjunction with Akvaplan NIVA and the Norse Institute for Nature Research. I got this info from a Dutch popular science book (2004), not from the Google search above. So there should be more info there. Might even be enough for a separate article. DirkvdM (talk) 08:14, 3 July 2008 (UTC)

Correct me if I am wrong, but I heard the project folded. 202.169.182.10 (talk) 23:59, 13 July 2008 (UTC)

Tidal Swell Generator ?

There's another type of generator similar to a wave generator. It gets its power by bobbing up and down on the surface, with an anchor at the ocean floor. I hope you nice wikipedia super-sleuths find time to add it. - Kristan Wifler

Swells are not tides: swells find their origin in wind, not gravity. You can find some of these devices at Wave power, e.g. the AWS (Archimedes Wave Swing). -- Crowsnest (talk) 18:02, 12 July 2008 (UTC)

open center turbine

is the open center turbine[4] (ref) a type of shrouded turbine ? Mion (talk) 09:25, 23 September 2008 (UTC)

Cleanup

I've started on a cleanup of this article, which I'm sure will be contentious. There has been too much emphasis on one particular technology in the tidal streams section and I've put that in a separate article. Please consider the balance carefully before reverting that. At the moment it's far from clear which will win and a Wiki article needs to be more balanced. We do need at least a more encompassing environmental impacts section which I will try and provide shortly. There's quite a bit more needs doing. Chris55 (talk) 17:47, 5 October 2008 (UTC)

Chapter removed

I removed this small chapter:

Energy efficiency

Tidal energy has an efficiency of 80% in converting the potential energy of the water into electricity,[5] which is efficient compared to other energy resources such as solar power or fossil fuel power plants.

Which seems to me fundamentally misguided: according to the (very poor) source cited, the 80% would be the fraction of potential energy available for electricity generation, to which one should add generator inefficiencies, etc. Alfio (talk) 12:06, 7 October 2008 (UTC)

Merger Proposal

The Marine current power article should be merged into this one, as it deals with a very similar method of power generation using oceans.

Dialectric (talk) 10:49, 8 October 2008 (UTC)

I support the merge. Marine current power is just a stub which can easily be incorporated. The alternative would be to split this article into three, i.e. tidal stream generators (including Marine current power) and tidal barrage systems as separate articles, with this article as a disambiguation or small overview article. But at the moment I think it is still manageable and overviewable, so a split is not direct necessary. -- Crowsnest (talk) 10:55, 8 October 2008 (UTC)

I agree, particularly as there is already a Marine Current Turbines article which gives much greater detail on that company's activities. Googling "Marine current power" gets 1,550 hits compared with 5,370 for "Tidal Stream energy" so both terms are in use, and I think an "also called" reference is suitable. There's already a redirection from Tidal stream energy and Tidal stream power (3,760 hits) to the section and my feeling is it's best to keep this as one article for the time being. (Only 753 hits for Marine current energy.) I don't think non-tidal marine currents are a significant factor yet though they may be in the future. Clearly the table at the end of the barrage section needs sorting out as a number of its references are to tidal stream projects and "basin area" is irrelevant for them. Chris55 (talk) 10:19, 9 October 2008 (UTC)

I'm having second thoughts. Marine current is not only a more general term than tidal but the energy potentials are much higher. Take this quote from an official US agency: "It has been estimated that capturing just 1/1,000th of the available energy from the Gulf Stream, which has 21,000 times more energy than Niagara Falls in a flow of water that is 50 times the total flow of all the world’s freshwater rivers, would supply Florida with 35% of its electrical needs."[6] Look by contrast at the discussion of the relatively limited yield of tidal power earlier on this page. The technology may not yet be there but we shouldn't confuse the two. I'm beginning to think a small MCP article that references a bigger TSE article (and vice-versa) is a better option. Chris55 (talk) 11:19, 9 October 2008 (UTC)

You are right, not all marine currents are tidal. So they should be distinguished, although there is not yet technology to harvest energy from these ocean currents. So, as far as I am concerned: Go ahead! -- Crowsnest (talk) 17:46, 9 October 2008 (UTC)

Ok, I've made a start. A lot more needs to be added, but does this make a viable structure? Chris55 (talk) 20:30, 11 October 2008 (UTC)

Given the absence of other comments on this, I declare the proposal defeated and will remove the merge proposals Chris55 (talk) 15:54, 18 October 2008 (UTC)

Gorlov is not an improved version of the Darrieus

Gorlov has claimed efficiencies in water of up to 38% compared with the existing Darrieus turbine. However this has been disputed by both Professor Memo Corio from Naples University and Dr Brian Kirke for South Australia's University among many others. In recent trials off the coast of Vancouver the Gorlov turbine was tested by independent experts and found to be almost identicle to the Darrieus in performance producing nowhere near 35% - 38% in efficiency As claimed by Gorlov. The reference to the Gorlov being an improved version of the Darrieus is erroneous and misleading and should be changed.202.169.176.97 (talk) 22:43, 25 October 2008 (UTC)

Tidal lagoons

this news item may intrest the editors of this article.Engineman (talk) 16:43, 16 December 2008 (UTC) http://www.claverton-energy.com/parsons-brinckerhoff-has-made-huge-miscalculations-on-severn-estuary-tidal-lagoons%e2%80%99-costs.html

Total tidal power potential

I removed:

"The total potential tidal power of the world has been estimated to be about 64 GW." (Modern Electric Vehicle Technology C. C. Chan and K. T. Chau.). For comparison, as of 2002 Canada had 67 GW of installed hydroelectric capacity (Natural Resources Canada -- About Hydroelectric Energy).

With only already a dissipation rate of tidal energy of 3.7 Terawatt — see e.g. Munk, W. (1998), "Abyssal recipes II: energetics of tidal and wind mixing", Deep Sea Research Part I Oceanographic Research Papers, 45: 1977, doi:10.1016/S0967-0637(98)00070-3, which for a substantial amount is due to bottom friction in shallow seas — a maximum of 64 GW tidal power potential seems low. Also, the given reference, a book on "Modern Electric Vehicle Technology", is quite off-topic and only gives this number without reference or calculation. Unfortunately, I am not aware of better founded estimates, with reliable references, which are welcome. -- Crowsnest (talk) 15:35, 29 July 2008 (UTC)

I appreciate the feedback and I too would like some better estimates. Some quick math suggests some bounds: If we could directly use earth's rotational kinetic energy, we could do so for 3.87×10⁸ years (at 2005 total worldwide energy consumption rates). This would consume 75% of the earth's rotational kinetic energy and have the effect of adding 0.22ms / year to the length of earth's day over that time. Earth's day currently lengthens by about 0.023ms / year, so this seems like a significant impact. Those numbers assume 100% efficient conversion so the reality would be an even greater impact. Dee Jay Randall (talk) 14:50, 30 July 2008 (UTC)

An intriguing calculation but I fail to see its relevance. Most climate change scientists are criticized for making 100 year calculations, but you are extending this a million times! Chris55 (talk) 21:19, 15 September 2008 (UTC)

With reference to the 64GW estimate, there is a detailed estimate here of the potential to the UK of 60TWh which corresponds to an average of about 7GW. That suggests that 64GW is almost certainly too low but is within an order of magnitude of being right, at least using nearly available technology. It would seem likely the Chan & Chau book is referring only to barrage-type tidal schemes. Chris55 (talk) 21:58, 15 September 2008 (UTC)

On a world with sea & no land, there would be tides in the open sea, over an enormous area, but of low amplitude. In the absence of land, there would be no way to harness the rise & fall of water. On Earth, potential global tidal power depends on the disposition of the continents, & those sites that by chance allow funnelling of the tidal bulge as it passes round the Earth. The land also has tides, & rise & fall, but much less than water. Estimates of potential global tidal power need a site by site analysis. --DavidJErskine (talk) 07:42, 4 April 2009 (UTC)

New idea

Would it be possible to add a section about potential new ideas for generating electricity from the tides . I've come up with a new idea ( somebody else may have had the idea already ) for a tidal range power generator . It basically consists of a deep pool of seawater ( 5m- 40m , depending on the tidal range and the use to which to pool is being put ) contained in a large flat bottomed vessel , perhaps 100m-500m across . The vessel is floating on the sea , not sat on the seabed as in the case of a tidal lagoon , with a bubble of trapped air underneath for buoyancy . The vessel is supported and held in place on hydraulically powered columns . As the tide rises , the vessel floats up till it reaches the highest point . Then the hydraulic columns lock in place , supporting the vessel as the tide drops . When the tide nears is low point , the vessel is allowed to descend slowly . As it does so , it's weight forces hydraulic fluid in the columns through turbines at very high pressure to generate electricity . Because the fluid is forced at high pressure , it means much smaller , more efficient and cheaper turbines can be used . It also means that no marine life is injured or killed in the turbine , and the turbine is not corroded by the seawater or by debris . A design like this would use far less construction material than a tidal lagoon structure , since the vessel containing the the water does not need to extend down to the seabed , only slightly deeper than the tidal range . It can also be used in water considered too deep for a tidal lagoon or barrage . The pool of water contained in the vessel is intended to be used either for growing algae , fish farming , as a solar thermal storage system , or the entire vessel simply acting as a platform for supporting other renewables such as a solar power array or wind turbines . No doubt many other uses can be found . If you are interested in this idea please contact me at kiddich@hotmail.com . Flumstead (talk • contribs) 13:29, 19 March 2009 (UTC)

Inclusion of your idea in the article requires verifiability by reliable sources, e.g. by mainstream news organisations, or a publication in a peer-reviewed scientific journal. Otherwise, it would be considered original research and not be publishable on Wikipedia: this is an online encyclopedia, so it includes condensed information on what has been published before in other, reliable, sources. To me it sounds like original research, although you mentioned that others may have had the same idea (and may have published on it in reliable sources). If it is original research, and you think it is important and want to promote it somehow, I would advise not to try to insert it on Wikipedia now: there is a large chance it will be removed, so a spill of your efforts. But to concentrate on working your idea out. After being published in what Wikipedia considers to be reliable sources — perhaps, if others had the same idea, these references already exist — it can of course be included. -- Crowsnest (talk) 17:14, 19 March 2009 (UTC)

Conventional tidal power holds seawater in a natural enclosure such as a cove. Your design contains the water in a manufactured product, so is vastly more expensive. ---DavidJErskine (talk) 06:42, 4 April 2009 (UTC)

If there are reliable sources confirming this scheme is too expensive, that also may be included in the article (if not given overdue weight). -- Crowsnest (talk) 20:09, 10 April 2009 (UTC)

Tidal power schemes being considered

The section entitled "Tidal power schemes being considered" mentions a project in Argentina whose location is described as "San Jose". I think that the source of this information should be checked to make sure that the location in question is not "Golfo San Jose", which is a large gulf/bay/lagoon on the north side of the Valdes Peninsula, rather than the city of San Jose. The Golfo San Jose presents quite unusual geographic features, and has been under consideration as a location for a tidal power project since at least 1930. Thomas.Hedden (talk) 04:14, 19 February 2009 (UTC)

I added a {{refimprove}} template to this section, since reliable sources for most entries in the table are missing. If no references are provided in due time, unsourced material may be removed. -- Crowsnest (talk) 10:28, 1 March 2009 (UTC)

On short term, I will start removing entries not verifiable through reliable secondary sources. -- Crowsnest (talk) 22:41, 9 April 2009 (UTC)

I removed unsourced material. But several of the remaining ones are still badly sourced: Penzhinskaya Bay (Russia), and Yalu river (China). As well as some in Tidal power#Potential sites, e.g. Alderney. -- Crowsnest (talk) 22:54, 19 April 2009 (UTC)

Clarification of the equation for calculating energy at a tidal power site

The equation has a term h, for tidal range, the height of the tide. The term is squared, & this may puzzle some readers. If a mass of fixed magnitude is raised above the ground, its potential energy increases linearly with height. In the case of a tidal power site, as the tide rises in a basin, the mass of water rises as its height increases, so the term h is used twice. Double the tidal range, & there is double the height, & also double the mass of water. --DavidJErskine (talk) 09:28, 4 April 2009 (UTC)

I saw this too. There was other flakey physics in the section "Pumping" too. It needed to be fixed or deleted right away because it was just so wrong. I didn't have time to fix it so I deleted it. I would have needed to try to figure out what the writer really wanted to say and I didn't have the time. If there is a kernel of truth somewhere, maybe someone can find it and fix it. Maybe it has something to do with the volume increasing more rapidly per foot of height because the "walls" of the bay are not vertical? Who knows? The error jumped at me and I had to fix it. I'm glad to see I'm not the only one to see it! 72.93.171.64 (talk) 01:28, 14 April 2009 (UTC)

Sorry to disappoint you, but it is correct, see Tidal power#Energy calculations 2 and given reference. The potential energy of a fluid particle with volume dV with respect to a reference level, say z=0 is ρgz dV. For a vertical-walled basin with horizontal area A and filled up to z=h, the potential energy is the integral of ρgz over the volume, so PE = ½ρgAh². -- Crowsnest (talk) 01:38, 14 April 2009 (UTC)

Surprising. I know I jumped fast. Incorrect physics is so common in Wikipedia I expect it first. The paragraph "smelled" a little like energy imbalance, I expected it and acted too fast. It's still hard to see where the extra energy comes from...okay, now I see it...but it's still bizarre! 72.93.171.64 (talk) 03:13, 14 April 2009 (UTC)

There is nothing bizarre. It is because you try to compare a solid mechanics formula with a fluid mechanics formula. If you consider a barrage with the shape of a cube with a lentgh "a". In solid mechanics Ep = m * g * h = (ρ*a³) * g * a/2. In fluid mechanics Ep = 1/2 * A * ρ * g * a² = 1/2 * a² * ρ * g * a². Fortunately, it is exactly the same result when u take a fluid mechanics formula and u extend it to a macro object. So if you had a new cube of water above the former one, the weight is multiplied by two and the height of the gravity point is multiplied by two too so the total energy is multiplied by 4.Couposanto (talk) 14:12, 14 April 2009 (UTC)

Tidal Power in remote areas

It should be mentioned that in the case of a site for tidal power which is attractive but remote, there is the option of using the power to smelt aluminium on a large scale at the site. Such a scheme would need a good port for shipping aluminium ore in and aluminium metal out. --DavidJErskine (talk) 09:37, 4 April 2009 (UTC)

Timor Sea

There is large potential for tidal power along the Kimberley coast of North West Australia, an indented coastline with a tidal range of 7m, extending roughly EW for 500 km. I have added a reference for this site. In Australia we are aware of the Kimberley region as having impressive potenbtial for tidal power, but we have not heard of other sites in the north of Australia. --DavidJErskine (talk) 09:55, 4 April 2009 (UTC)

The Kimberley Coast is 3 thousand miles from the Torres Strait. Check Wikipedia geography. —Preceding unsigned comment added by 59.86.173.105 (talk) 21:47, 23 November 2009 (UTC)

Thankyou anon. I have corrected the title from Torres Strait to Timor Sea. --DavidJErskine (talk) 06:35, 16 March 2010 (UTC)

Canals

The Cape Cod Canal in Massachussetes has ocean on both sides and thus has tides that go through it both ways. There is a significant height difference between both sides due to tidal effects of the moon over long distances. Also it is quite deep and narrow. There are some other sites but this is probably the one nearest to a large population center. Also the canal is an artificial construct so damage to the environment would be negligible compared to damming an estuary. .--Zer0Cool (talk) 12:07, 01 September 2010 (UTC)

Edits

I have make an unified edit with all the links to internal Wikipedia links. I have to do a lot of editions before, because Wikipedia is not ready to edit with mobile devices, some text can be cut, edition is slow (you have to edit section by section) and so on. Regards.--Nopetro (talk) 13:19, 14 July 2009 (UTC)

New Ideas Tidal power

I have had an idea for many years to exploit tidal power and have done nothing about it...life has got in the way...my idea does not exploit the passage or velocity of the tide and there are no turbines. I have had a look at the current ideas available and no one is using my concept. I am not an engineer, my background is in building and consturction and so have limitied knowledge as to how to proceed with my idea. Interested please feel free to contact me by email ^{[email address removed]} or post on here...thanks Les 06/03/2010 —Preceding unsigned comment added by 77.194.40.180 (talk) 10:24, 6 March 2010 (UTC)

Cleanup

Hi. I plan of cutting down a big chunks of this article and remove duplicates. I also plan on moving the three main types of tidal power generation to its corrosponding main articles: tidal barrage, tidal stream generator, and dynamic tidal power, leaving behind just a summary with a "main article" link in its sections. I intend to do this by a week or two if no one objects. Kind regards. Rehman 13:53, 3 November 2010 (UTC)

Well done, Rehman, I think this is an improvement. Many thanks. UNguyinChina —Preceding undated comment added 06:30, 11 November 2010 (UTC).

You're welcome ;) Rehman 06:48, 11 November 2010 (UTC)

Seems you're an experienced editor. Do you have any tips on how to further improve the 'dynamic tidal power' page? I'd like to make the page more complete and I've got quite a lot of materials here, such as academic research, graphics, recent developments, and links to recent publications. What do you think it could use? UNguyinChina —Preceding undated comment added 07:11, 11 November 2010 (UTC).

Sorry for the late reply. My main concern was that the article needs further diagrams to explain, and a little re-wording here and there. But I see you have already taken care of those; nice work ;). Any further improvements would eventually flow in when needed, as with the rest of the Wikipedia articles. Rehman 09:34, 11 November 2010 (UTC)

Thank you, Rehman. Please let me know if you have any further ideas for the page. UNguyinChina —Preceding unsigned comment added by 123.113.152.177 (talk) 10:08, 11 November 2010 (UTC)

You're welcome. Just a side not, after you finished typing a reply (and before you hit "save page"), type four tildes (~~~~) at the end of your message to sign it, so that others may know who posted the comment, and when. Kind regards. Rehman 10:15, 11 November 2010 (UTC)

Rehman: Many thanks for the pointers. This is very helpful. (114.248.126.243 (talk) 13:21, 11 November 2010 (UTC))

Rehman - you are a great editor but have little understanding of the importance of some of the material you have removed. Industry technology could be astrongly argued by many to be highly relevent to the this page as well as independent third party expert comments - all gone - ALL GONE. You have no idea how impoertant this material was to both the researchers and the industry as a whole. Who's going to fix this ????? —Preceding unsigned comment added by 202.169.177.131 (talk) 02:30, 24 December 2010 (UTC)

Thank you, but I think you misunderstood; I did not remove anything, just merely moved it to sub-articles: tidal barrage, tidal stream generator, and dynamic tidal power. This page is too large to hold all of them. Rehman 02:57, 24 December 2010 (UTC)

Maybe I mis-understood but what happened to the rest of the subject matter like venturis (arguably the jet engine of turbien design) and the formulas for power and the peer reviews that students come here to cite for their research ??? As a retired engineer with a background in hydrology I have never heard or come across "dynamic tidal power" - there are no proof of concept reports no commercial prototypes and no peer reviews yet they are cited here as fact - who is responsible for this fanciful fairly tale ! - who on this earth authorised this rot ??? Return the site to it's former state and do not fiddle with subject matter unless it is to do with spelling or grammar. —Preceding unsigned comment added by 202.169.177.131 (talk) 11:13, 25 December 2010 (UTC)

Just to clarify, I did not remove any content directly from this page; just merely separated across four pages (including this). If you have any concerns regarding content, please use the relevant article's talkpage, so that the related editors could see into (i.e. for dynamic tidal power, please use its talkpage). Content on those pages may be altered/removed depending on the situation there; nothing to do with my splitting of the page. Rehman 00:31, 26 December 2010 (UTC)

You stated above that you removed large chunks of material - this is nothing short of vandalism - who gave you the right to do throw away years of hard work and editing by dedicated researchers and peers who toiled to place here information that has been of in valuable service to all - "I did not remove any contant from this page" !? Sure. — Preceding unsigned comment added by 59.86.171.114 (talk • contribs) 06:49, 27 December 2010 (UTC)

"Removing (i.e. deleting for good)", and "moving (to another page)", are two different things... Read again, what I mean by cutting down this article was that I plan on cutting down the length of this page, by splitting content to separate pages. Rehman 07:17, 27 December 2010 (UTC)

Nothing has been "thrown away", material has just been moved (reshuffled) to articles pointed to in this article. -- Crowsnest (talk) 08:38, 27 December 2010 (UTC)

"if no one objects" - I object in the strongest possible way at how this editor has changed this site to suit his personal whim. Many editors laboured many years over this site as a "one stop shop" for information nat a site where information has been scattered to the wind on one persons brain explosion. The site has been butchered and it remains to be seen whether it will ever be returned to it origional state. I strogly believe people with little or no understanding of the subject matter - the Dynamic Tidal Power editing a point in question - be allowed to make wholesale editorial changes. I will repeat it again - formulas are missing, peer reviews are missing, vital information on advances in technology have all been moved making research and assessment all that much harder. Is this what Wikipedia has come! A site where anarchy has become the standard ???? —Preceding unsigned comment added by 59.86.171.114 (talk) 22:24, 27 December 2010 (UTC)