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Please let me have any comments (good or bad,) relating to my Buoyancy Engine idea
(Did I get that right?)
Nice annimation! It's not clear to me what all the bits do. I understand the pontoon rising and falling in the tide, but I don't understand what the other tank thing is doing. Maybe a bit of a description might help?
BTW, assuming the energy is derived from the rise and fall of the pontoon, have you worked out a size to power ratio? Something along the lines of kilowatts per cubic meter or 1000 kg of displacement might be helpful. I think you should be able to get a good idea of it from the mass of water displaced by the pontoon, and the distance it moves in time.
Ah, but if the storage vessel is 67,000m3, the pontoon will have to displace six times that volume, or about 400,000 cubic meters, otherwise it will sink. A cubic meter of water weighs about 1t, so your pontoon displacement is about 400,000t which is about 80% of the supertanker I mentioned, and that is only capable of generating 0.5MW, so you are only going to get 0.4MW, and that's without allowing for the inevitable losses in the systemIt doesn't matter how you cut it, but ultimately, the thing that is doing the work is the tide lifting the mass of water displaced by the pontoon against gravity. If your calculation says that you are doing more work than that, you are trying to get something for nothing, which has never worked thus far.
The power generation calculation depends on the depth and the size of the pipe.
seems to me that Geezer is correct (damn) -
Quote from: Mootle on 17/10/2011 22:31:25The power generation calculation depends on the depth and the size of the pipe.Alas, it does not. To generate power you need to do work, and the only thing that's doing any work is the tide elevating the pontoon against the force exerted by the cable. It's quite simple to determine how much work the tide does, or the power, which is the rate of doing work. I calculated that in my previous posts.You can do anything you like with systems of gears and cables, but you will never be able to use them to multiply the amount of work done by the tide acting on the pontoon. The second law of thermodynamics has yet to be broken.
What is preventing horizontal and rotary motion by the storage vessel" and pontoon" due to ocean currents, causing the cables to become twisted/tangled which would prevention operation ?.
If the answer is they are enclosed in an almost watertight lift-shaft built on the seabed thats gonna cost a fortune to construct to a standard which will survive being in the ocean.
BTW I suspect it would only be a matter of time before marine fouling would clog-up the pulleys.
seems to me that Geezer is correct (damn) - I will note also that 400k metric tonnes deadweight (available displacement for cargo - or in your case provide buoyancy force) is bigger than all but a dozen or ships in the world today. Large cargo ships (no one says supertankers apart from the press) are not designed to be pulled from underneath by cables but to have cargo spread evenly over about 15000m2 of bottom. For your guidance - to construct a tanker of 400k dwt you use about us$25-30million worth of steel
OK, let's have another look at the maths."A turbine and generator with a working head of 50m and a Storage Vessel volume of 67,000m3 would provide the "In the right units, pressure times volume = energy50m of depth in water with a density of 1000 kg/m^3 will exert a pressure of (rho) g h =1000 X 10 * 50 =500,000 pascal (that's about right: it's 5 bar which is what you would expect with 10m head of water being about 1 bar)The volume is 67000 so the stored energy is 500,000*67,00033.5 GJThat sounds good, but it's only roughly the energy stored in 1000 litres of cooking oil or gasoline.That energy is available twice a day so that's once every 12 hour720 minutes43200 secondsSo the power is 33,500,000,000 /43,200 which gives you0.78MW average power. That's not a lot. To do that you would need 67000 tons moving up and down by 50 metres or roughly 500,000 tons moving up and down 8.3 metres.But it only moves by about 4 metres so the energy is only half what I calculated.So the power output is about 400KW for a roughly supertanker sized pontoon.That's the same ballpark as Geezer's figure. (Possibly the reason it's bigger is because I haven't included the energy needed to blow the tank clear each time)Do you have any real evidence that the output will be better?If not, perhaps you would do better to study some thermodynamics rather than say things like "However, strongly you assert something it means nothing without proof!"
Incidentally, you might like to answer the questions I asked earlier."Why have 6 ropes + pulleys when you can just put a gearbox on the generator shaft?"
Quote from: Geezer on 18/10/2011 03:29:55Quote from: Mootle on 17/10/2011 22:31:25The power generation calculation depends on the depth and the size of the pipe.Alas, it does not. To generate power you need to do work, and the only thing that's doing any work is the tide elevating the pontoon against the force exerted by the cable. It's quite simple to determine how much work the tide does, or the power, which is the rate of doing work. I calculated that in my previous posts.You can do anything you like with systems of gears and cables, but you will never be able to use them to multiply the amount of work done by the tide acting on the pontoon. The second law of thermodynamics has yet to be broken.I offered to review your calculations or show you the calculations I've used. You've chosen a third option. Unfortunately, your way takes the debate no further forward and denies us a learning opportunity, where either you learn something new or I do. However, strongly you assert something it means nothing without proof!
Apparently you didn't like my calculations OK, here we go again, from the top!
Mootle,I looked your idea and wondered if you have thought of using another method that might use compressed air instead of the cables and pontoons.
btw please confirm if you now concede the point on capacity?
We done dis idea before dint we Here:How much work in the form of pressure is there at the bottom of the deep ocean?... oh, and here:Does deep ocean have potential energy due to pressure? 
The patent office are quite happy to take your money without checking (or caring) if the idea works.
The patent office are quite happy to take your money without checking (or caring) if the idea works.I still think this idea is pointless. It needs a really big construction project to make relatively little power.Fundamentally it can not extract more energy from the tide than my suggestion of a big box on a rope. The only aspect of it that might be novel enough to get a patent is the use of the rope and pulleys to convert a small movement with a large force into a larger movement with a smaller force. Obviously, that's been done before but probably not in this context because it doesn't offer any great advantage.
Quote from: Mootle on 20/10/2011 10:19:08btw please confirm if you now concede the point on capacity?What point? Are you saying your system will be able to produce more than 4.36 MWh per day?If you believe that is the case, please take a look at this informative video ...sorry, you cannot view external links. To see them, please
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fyi, each of the buoyancy engines would provide ca. 12MWh/day,
Then you are trying to violate the second law of thermodynamics. It's not up for "debate". It's really quite simple. You cannot extract more work from a system than the work that was put into the system. The tide is the thing that is putting in the work, but you seem determined to ignore that inconvenient fact.
My calculation clearly shows each generator can't possibly produce more than 4.36MWh per day (and it will actually be a lot less due to parasitic losses.) If there is a flaw in my calculation, you should be able point it out, quite easily. Either you don't understand basic science, or you didn't make any attempt to understand what I posted.
I'm not going to waste any more time trying to help you understand where you are going wrong, and please don't blame me if you are chased out of town by an angry mob of investors who want their money back. (You won't be able to blame the patent office either.)
Quote from: Bored chemist on 20/10/2011 19:10:14The patent office are quite happy to take your money without checking (or caring) if the idea works.I still think this idea is pointless. It needs a really big construction project to make relatively little power.Fundamentally it can not extract more energy from the tide than my suggestion of a big box on a rope. The only aspect of it that might be novel enough to get a patent is the use of the rope and pulleys to convert a small movement with a large force into a larger movement with a smaller force. Obviously, that's been done before but probably not in this context because it doesn't offer any great advantage.I'm not sure I agree with your comments regarding the IPO, at least this hasn't been my experience.
I only made one comment about the patent office. That comment is that they do not check if things work.Do you think they have the time or facilities to test all the inventions they are asked about?
Also, in your debate with Geezer you seem not to have understood where the discrepancy is.The fundamental difference is between what you are claiming and what the laws of physics will allow.If your ideas do not tally with reality then it is not reality that has got it wrong.
Incidentally, there is one aspect of inventions that the PO looks at before awarding a patent. They don't patent perpetual motion machines.If you were to connect the output of your system to a pump to make an "artificial tide" then you would have made a perpetual motion machine. They certainly wouldn't patent that.
Your system might provide a possible benefit in places where the tidal range is too small to use conventionally, but even there it would be pointless because there simply would not be enough energy available to make it worth while.
I asserted a nett energy of 12MWh/day.
Quote from: Mootle on 22/10/2011 17:43:37I asserted a nett energy of 12MWh/day. You can assert as often or as loudly as you care to, but according to the data you provided, it remains impossible to exceed 4.36mWh per day If it's so obvious to you that I mucked up the calculation I used to determine that figure, you might want to point out where I went wrong.
Quote from: Geezer on 22/10/2011 21:15:07Quote from: Mootle on 22/10/2011 17:43:37I asserted a nett energy of 12MWh/day. You can assert as often or as loudly as you care to, but according to the data you provided, it remains impossible to exceed 4.36mWh per day If it's so obvious to you that I mucked up the calculation I used to determine that figure, you might want to point out where I went wrong.I have, more than once, but to my frustration you've not conceded the point on rating nor have you followed the instruction and input the correct Pontoon volume into your energy calculation based on the 25:1 (rather than the 6:1, used for demonstration purpose of the ratchet pulley system in the schematic animation) gearing ratio. Further, I've modified Bored chemist's calculation as a check to take into account the twice daily operation and this verifies that my asserted energy balance is ok.From your comments, I can see where you've got the wrong end of the stick so in this regard I'm afraid that I've failed to properly convey the full operation of the system but this is something I plan to put right with the scaled animation.Once again, thank you for your input.
No wonder you keep getting the wrong answer.I already allowed for the fact that the tide rises twice a day. that's why my post includes this "That energy is available twice a day so that's once every 12 hour"So, if you don't change my maths to make it wrong, it pretty much tallies with Geezer's.
Rather than repeatedly saying that you have pointed out his error (which, as far as I can see, you have not) could you please point it out now?If it doesn't work with a 6 to one ratio, it also won't work with 25 to one. You don't get more energy out than the tide puts in, no matter how much rope you use.
I ask you to calculate how much energy you would need to use (with an idealised, perfect crane) to raise the pontoon, rather than using the tide.If it turns out to be less than 12MW Hr a day then you don't need the tide at all.You have then made a perpetual motion machine that doesn't rely on the moon.Your proposal breaches that principle of conservation of energy.It's that sort of perpetual motion machine, and the PO won't patent it. (And if they cared they would check- they don't have time or kit to do either)
When it comes down to it, for the cost of a supertanker sized building project (and then some for the other structures) you can get a bit less than 0.4MW
You say that electricity is £100 per MW Hr, fair enough.
0.4MW for 24Hr gives £960 per day in revenue. Call it £1000 to make the maths easyThe money markets are screwed at the moment so let's assume you can borrow money at 2% (which is ridiculously cheap)1000 a day is £365000 per year which will cover a debt (interest only without paying capital) of £18MBut the steel alone will cost you £15MThat leaves no room for any of the generator, the concrete to hold it in pace, paying off the capital, designing, building and so on.
Your idea doesn't make sense.With a more realistic interest rate, like 5%, it still makes no sense, even if we ignore the laws of physics and let you get out twice as much energy as the ocean puts in.
I understand perfectly well how it works, and I also understand that you have magically made the pontoon more than four time larger to let you reverse into your original, incorrect, power calculation.The pontoon is now 3.5 times larger than the World's biggest supertanker (er, or whatever Matt wants us to call it.)This isn't the Tommmy Cooper Show ewe know "The 'reality' is that Mootle put the wrong figures into the calculation - a point that I've made several times. If anything, I find it amusing that people who obviously have an understanding of the principles cannot concede a point when the error has been clearly identified."
What I agree is that you never even bothered to look at what BC and I posted (despite repeated requests), because, if you had, you would have had ample opportunity to object to the numbers we were using.If you were proposing a displacement of 1.7Gt, why didn't you simply point that out five or more days ago? Did I hide that information in my calculation? Was the pontoon displacement never discussed? In fact, up until now, you have not provided ANY value for the displacement of the pontoon, despite the fact that it is critical in determining the amount of work done. I don't suppose that's because you only just worked it out based on the information we gave you?EDIT: Correction - that should be 1.7Mt (not 1.7Gt)
Mootle, old bean, if you look back down the thread you will see I said this;"If the pontoon displaces 400,000t or 400,000,000kg (which it must in order to submerge a 67,000 cubic meter storage vessel with a 6:1 mechanical ratio) the force in the cable is 9.81 times 400,000,000 = 3,924,000,000N."I also asked you several times to point out any errors in my calculation.Now you are saying you knew all along that I should have been using a displacement of more than four times that amount and a ratio of 25:1?I really hope you didn't know that all along, because if you did, and you didn't bring it up, you were simply being a troll. I will give you the benefit of the doubt and assume that you had no idea what the displacement was until you recently figured it out.
Mootle,What's the reason for not building a scale model?