Wave power feasibility check
Posted on: April 9, 2011 - 12:37am
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Wave power feasibility check
I don't really know that much about this kind of thing so I was hoping someone could tell me if this idea is feasible. It's an idea for generating electricity from waves. The reason I like this idea is because it keeps the generators outside of the water, and it could probably be made with simple mechanisms. Tell me if you think it would work, and if so weather it's worth doing. I attached a picture that explains the whole concept. Please excuse my poor drawing.
I'm getting tired, but yeah, some people have been working on this. I'm not sure what the status is on the research.
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On the discovery channel I saw someone making a tube, sticking a rotor in it, so that the waves would move the air in the tube, moving the rotor, generating a voltage.
It wasn't really efficient, since the water would only move a little bit of air per time unit. But it is reliable, since there are always waves...
The problem is the buoyancy greatly minimizes the force of the mass. The second problem is the angle differential between the mass vector and the generator input. You'd be better off with the generators horizontally at sea level, directly in line with the mass vector.
Your whole design would be better if you had a very large, 'barn door' on hinges submerged, with the cables attached midway up the free swinging end, transferring the motion of the currents into the generators submerged horizontally to the midway attachment point. The mass of the ocean would be a more efficient transfer of polar moment of inertia with the barn door type lever, than a floating 'rubber duck' type mass.
In any event, it's not nearly as efficient, or cost effective as using gravity to pull water down past an impeller, or wind past an impeller, or converting solar energy using screen printed solar panels, in terms of 'free energy'.
I keep asking myself " Are they just playin' stupid, or are they just plain stupid?..."
"To explain the unknown by the known is a logical procedure; to explain the known by the unknown is a form of theological lunacy" : David Brooks
" Only on the subject of God can smart people still imagine that they reap the fruits of human intelligence even as they plow them under." : Sam Harris
Pretty much a wind power concept if you are talking about waves pushing something up and down. The only difficulty is in designing something that wont need maintenance every other day and cost effectiveness.
edit: and it would probably not be as effective as wind. We haven't even got wind power down pat yet.
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Well, a friend's son is working on a degree in mechanical engineering and this is one of his projects. I am not really clear on the details of what he is doing (but then at his level, he probably in not all that clear either).
His system involves a long string of floats where the flex of the joints provides the motion for the system. I don't know what he is using for transducers. Even so, it seems to me that there are a couple of things to take into account.
First, the mechanical resistance in the joints has to be lower than the energy available in a single wave or the system would not flex much, if at all.
Second, the length of each floating element would have to be close to or just below the nominal wavelength for any given location in order to get the best use of the waves. That is likely to be somewhat specific to a given location.
Then too, if deep water is available, any storms could temporarily change the dominant wavelength, thus rendering the system less effective until the seas calm down again.
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Hey RatDog. The idea is theoretically sound, but it may involve too many practical considerations in order to make it work properly.
The main problem I see off the top of my head is that the up/down or left/right motion, that would be the source of energy, would be highly dependent on the frequency (like radio frequency or sound frequency) of the waves, and you would have to tune the mechanism (like tuning a radio to pick up a specific frequency/station) in order to get the energy to start being collected efficiently.
If it wasn't tuned just right (say, tuned for 1.5 waves per second instead of the local water's actual frequency of 1.3 wave per scond (or worse, 1 wave per second), then the mechanism would just flop around a bit without making the kinds of smooth, regular motions that work best with those kinds of mechanisms.
Imagine trying to pedal a bike in high-gear by tapping down on the pedals rapidly, tap-tap-tap. You wouldn't be able to get the bike going. You would need long, strong, regular pushes, not rapid taps.
Similarly, if the bike was in low-gear and you tried using strong, slow pushes, you would get moving, yes, but you would be pedalling too slow to gain any speed.
You would need the right gearing of the mechanism tuned to the right speed of waves. It is theoretically possible, yes. But probably too complicated in practice.
I think your scheme could work if it used very large weights (like the size of huge boats) and relied more on the daily tide rather than on waves. Then you'd be able to tune it once based on the tidal rhythm. However, I suspect that such huge mechanisms would introduce a whole other set of problems and inefficiencies.
If you're interested in learning about the frequency dependency of such systems, I recommend learning a little bit about capacitors and inductors in basic electric circuit physics. Although it sounds unrelated, all these periodic/cyclical physical systems share deep similarities in terms of how they actually work in physics.
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You would probably double the potential power output just by simply adding a keel to the bottom of the float, but it would still be grossly inefficient compared to existing free energy systems.
I keep asking myself " Are they just playin' stupid, or are they just plain stupid?..."
"To explain the unknown by the known is a logical procedure; to explain the known by the unknown is a form of theological lunacy" : David Brooks
" Only on the subject of God can smart people still imagine that they reap the fruits of human intelligence even as they plow them under." : Sam Harris
Thanks for the comments every. I really appreciate every ones honest opinions.
Oscillating water column: Air enters a chamber through a hole and is compressed and decompressed by wave movement. A high-powered turbine catches the air as it’s decompressed.
“Over topping device”: A large structure, shore-based or in the ocean, that channels waves into a basin. When the basin’s water level becomes higher than the ocean’s, the basin is drained. The technology is similar to a hydropower system, in which draining water runs a turbine. http://www.smartplanet.com/people/blog/pure-genius/how-it-works-wave-power/3769/
You couldn't get a more stable (24/7) output than a hydroelectric dam, and the higher the dam, the more energy the water has due to gravitational force.
Due to gravity, it takes just under 28 square inches of water (at rest) to equal 1 PSI of downward force.
Factor in the leverage ratio of your impeller geometry, it's reciprocating mass, and efficiency of your generator, and you can calculate the amount of watts you can generate from the mass of the water acting upon the lever.
The beauty of windmills is their low initial cost, and the maintenance costs vs power output. Same with screen printed solar cells. If you could automate and scale up production, the unit costs of both of these systems would drop exponentially.
As far as your design, the 2 major flaws are the angle differential between the force acting upon your float, and the generator. A very simply way to model it in your mind, is to think of it in reverse.
Imagine if you were in a boat trying to pull your barge (float) along the water. Would you attach the line to the transom, in line with the barge, or would you tie the line to the top of a 40' mast?
The second thing you have to take into account is how little force it takes to move a large mass floating on water, due to the low coefficient of drag between the vessel and the fluid. This is why large ocean liners can by 'tugged' by little boats, with a few hundred horsepower with props that are only a handful of inches in diameter.
I keep asking myself " Are they just playin' stupid, or are they just plain stupid?..."
"To explain the unknown by the known is a logical procedure; to explain the known by the unknown is a form of theological lunacy" : David Brooks
" Only on the subject of God can smart people still imagine that they reap the fruits of human intelligence even as they plow them under." : Sam Harris
Hydro is great. I wish we had more of it. I suppose the main drawbacks are environmental and land usage, but personal I think the benefits out way the cost. The best thing about it is that it's dispatchable so it can help with the variability of solar and wind.
I'm not to sure about the first flaw. Would it help if compressed air was used instead. Maybe you could have a bunch of these units lined up parallel to the beach, and all of them could feed compressed air to a single electric generator on shore.
Nearly a concept wind waves grow if you talk something up and down. The only problem is to design something that will not require maintenance every two days and profitability.
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Hydro plants can help smooth the variability of other sources, via pumped storage.
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That's true it can. It's also possible to use other forms of energy storage for the same thing, but pump storage combined with existing hydro plants is probably the most cost effective methods.
I've been doing a lot of reading about renewable energy lately. It seems that if we are going to have any kind of bright future renewable energy is needed. Based on what I read there seems to be four different ways to integrate variable energy sources into the grid.
Demand side management: This includes things like smart girds, price incentives and any other ways to directly or indirectly control how customers use power.
Supply side management: This included all kinds of dispatchable generation. Some examples of which include hydro plants, gas turbines, and spinning reserve.
Improved grids and electricity markets: This includes things like uniform grid protocols, energy trading between countries, and supper grids. The idea behind these being that if you can connect a lot of variable sources with a lot of variable demand that it will average out somehow. Actually I'm not to sure about the whole supper grid idea. I was wondering if you could give me your opinion on it. You know a lot more about electronics then I do.
Energy storage: This includes a number of different technologies. I found a fairly good table on line.
"The two main applications of energy storage technologies are for power – driven by the needs for power quality and bridging power – and for energy management. In power applications, stored energy is only applied for seconds or less to assure continuity of quality power, or it might be used for slightly longer (a few minutes) to assure continuity of service when switching from one source of energy generation to another. For energy management applications, storage media is used to decouple the timing of generation and consumption of electric energy, as previously described. A typical application is load leveling, which involves the charging of storage when energy cost is low and utilization as needed. "
http://energystoragetrends.blogspot.com/2010/11/energy-storage-basics.html
Over all I think integrating variable power is possible, but difficult. Given thing like global warming and peek oil it is also probably necessary.