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Solar. Wind power. Wave power. Geothermal. Tidal power. If you're a regular EcoGeek reader, you're probably pretty familiar with the different major power generating alternatives to the burning of non-renewable fossil materials. But still, osmotic power generation is likely something you haven't heard of before. Your first question is likely 'How do you use osmosis to generate electricity?'
Osmosis is a process whereby water with two different concentrations of solution (in this case, salt) is separated by a semi-permeable membrane. Fresh water is able to pass through the membrane to the salt water side, but salt water cannot cross back in the other direction. This causes an increase in pressure on the salt water side, and this pressure difference is used to run a turbine which produces electricity.
Statkraft, a Norwegian renewable power company, has begun operations to use this process to generate electric power. The test facility, opened this week in Norway, is just a small demonstration plant which will produce only a few kilowatts of power. However, by 2015, Statkraft expects to be producing 25 megawatts of electricity by osmotic power.
Since the osmotic process requires a great deal of freshwater to function, we can forsee some serious problems for this system in the many parts of the word where the availability of fresh water is limited. The osmotic process also produces waste water that is saltier than freshwater, but not as salty as seawater, and the discharge of large quantities of this brackish water could be detrimental to local aquatic ecosystems.
via: Beyond the Beyond and Slashdot
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Comments (19)
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written by camarco, November 30, 2009
The Osmotic power plants are only suitable for river deltas so I can't see the problem for the local aquatic ecosystem (the fresh water is mixed with salt water anyways in a river delta...) But the relativly high purity of fresh water needed for the process may reduce the potential in "dirty" rivers and result in fresh water use conflicts.
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written by luis, November 30, 2009
On the face of it, and forseeing freshwater shortages in the future, this sounds like a stupid idea, whereas at the same time there's ongoing intensive research in energy-economical saltwater desalination!
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written by Matt, November 30, 2009
As long as you site this where a river emptys nito the sea/ocean there isn't any issue. You just take fresh water that was about to get mixed with salt water and "mix it" in the plant instead.
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written by Ken Heslip, November 30, 2009
That's a new one. It always seems to be the Nordic countries doing this great stuff.
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written by Gianni, November 30, 2009
The caveat at the end is somewhat misdirected. This technology is ONLY applicable where freshwater meets the sea, where it is going to mingle anyway, so there is no pressure on freshwater supplies. A more serious concern is the same as any estuarine development -- estuaries are about the richest and most productive ecosystems on the planet, and so anything that encourages industrial development and interrupts the natural cycles is a concern.
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written by Gianni, November 30, 2009
The caveat at the end is somewhat misdirected. This technology is ONLY applicable where freshwater meets the sea, where it is going to mingle anyway, so there is no pressure on freshwater supplies. A more serious concern is the same as any estuarine development -- estuaries are about the richest and most productive ecosystems on the planet, and so anything that encourages industrial development and interrupts the natural cycles is a concern.
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written by Piers Headley, November 30, 2009
The power plant is intended for use in fjord and river mouths where sweet and salt water mingel anyway, so the availability of fresh water and disposal of the salt is no problem. Might be able to power a lighthouse at least!
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written by Palmer Sperry, November 30, 2009
The osmotic process also produces waste water that is saltier than freshwater, but not as salty as seawater, and the discharge of large quantities of this brackish water could be detrimental to local aquatic ecosystems.
Since the logical place to install a system like this is where a fresh water river meets the sea (ie: where you're likely to find brackish water anyway), is it really going to affect the local ecosystem that much?
I suppose you might have to divert some of the river form far enough upstream to avoid too-brackish water entering the fresh side, and the resulting low-flow between that point and the sea could change things negatively.
Since the logical place to install a system like this is where a fresh water river meets the sea (ie: where you're likely to find brackish water anyway), is it really going to affect the local ecosystem that much?
I suppose you might have to divert some of the river form far enough upstream to avoid too-brackish water entering the fresh side, and the resulting low-flow between that point and the sea could change things negatively.
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written by Richard, November 30, 2009
Again. Another step towards energy self-sufficiency. Such works and studies deserve as much funding as it should- provided- that it becomes successful in the long run- provided, furthermore- that it benefits the environment.
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written by darius, November 30, 2009
Here is some interesting and much more technical discussion of this Osmosis process. Also pointing out that this could be a better use as energy storage solution.
http://www.talk-polywell.org/b...php?t=1430
http://www.talk-polywell.org/b...php?t=1430
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written by Dark Angel, November 30, 2009
I don't suppose anyone would consider directing the "waste" water from a plant like this into a de-sal plant? Since the waste has a lower salt concentration than the seawater normally used, wouldn't it reduce the energy requirements of making potable water? Also (having not read the full details) since the process relies on salt concentrations and not potability, couldn't otherwise undrinkable water that was otherwise low in salt be used instead of drinking quality water?
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written by driver8, December 01, 2009
This is a great idea but it is not new.They taught this in my oceanography class in high school back in 93.The fresh water can be used for drinking,wow no even mentioned that idea.The salt water goes back to were it came from,the ocean.If the power plant just uses the salt water for electricity,then dumps it back in the ocean how is it less salty if fresh water is removed from the salt water?If they are mixing the waters back together at discharge they really haven't changed the salinity,or could be matched to the waters source location for salinity.There is a lot of information lost in translation from the Norwegians to English and it shows in the article.I could go on for pages.
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written by Richard, December 01, 2009
I can't help but notice the highly-technical terminologies of the comments, but science is science. Nothing better than getting to the knitty-gritty of stuff. After all, the world depends on it.
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written by Vance Nepomuceno, December 07, 2009
This solution to our energy problems seems to be going the wrong direction. The world population is already facing a shortage of fresh water. One of the solutions for acquiring more fresh water is desalinization of ocean water. The problem with this is it costs too much energy and money for us to effectively do this. Creating energy with a by-product of saltwater maybe a step forward on the energy front but a couple steps back in the battle over a sustainable Earth.
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written by kurt klingbeil, December 09, 2009
Cool idea.
But... as with many "cool ideas", just because something CAN be done, doesn't mean it OUGHT to be done.
Fundamental principle which should always be applied is to evaluate:
** the TOTAL input of resources including brainpower, energy, materials (including their embodied energy), labour, that are expended
** the TOTAL return of energy and other perceived benefits
** the NET results accounting for startup, operating, cleanup, and resolution of collateral damage
** the LEVERAGE of development resources in broad duplication of the technology in other settings
** the RELATIVE value compared to other technologies one could choose to implement.
I usually advocate innovation but recognize that often incremental improvements to the "boring old way" turn out to yield a greater net benefit than latching onto the micro-benefits of some new sexy idea.
But... as with many "cool ideas", just because something CAN be done, doesn't mean it OUGHT to be done.
Fundamental principle which should always be applied is to evaluate:
** the TOTAL input of resources including brainpower, energy, materials (including their embodied energy), labour, that are expended
** the TOTAL return of energy and other perceived benefits
** the NET results accounting for startup, operating, cleanup, and resolution of collateral damage
** the LEVERAGE of development resources in broad duplication of the technology in other settings
** the RELATIVE value compared to other technologies one could choose to implement.
I usually advocate innovation but recognize that often incremental improvements to the "boring old way" turn out to yield a greater net benefit than latching onto the micro-benefits of some new sexy idea.
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written by Adam St. John, December 09, 2009
Bad Idea
written by luis, November 30, 2009
On the face of it, and forseeing freshwater shortages in the future, this sounds like a stupid idea, whereas at the same time there's ongoing intensive research in energy-economical saltwater desalination!
I agree. At the rate our freshwater sources are decreasing... this does not seem like a good idea at all. We need a more efficient desalination process. Why waste our drinking water for an relatively inefficient source of energy?
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written by Marcel Geers, December 10, 2009
Several comments have pointed out that drinking water shortages makes this a stupid technology. As other pointed out quite well, you will only use fresh water that would have mixed naturally otherwise. If you have a lack of fresh water, you surely will not be using the water to generate electricity.
Another place where salinity gradient power is researched is here in the Netherlands. We have several fresh water "reservoirs" where fresh water is released en mass at low tide. This causes sudden osmotic shocks for the sea life. This technology would actually IMPROVE the quality of the environment while maintaining the status quo in terms of water management.
Another place where salinity gradient power is researched is here in the Netherlands. We have several fresh water "reservoirs" where fresh water is released en mass at low tide. This causes sudden osmotic shocks for the sea life. This technology would actually IMPROVE the quality of the environment while maintaining the status quo in terms of water management.
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written by jagatveer singh brar, May 26, 2010
this method is good because electricity is generated and the salt contents are purified by several chemical or physical processes.
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I just feel I need to add that I used to work close to this plant. And also think it is interesting that the plant is located in a fjord that is quite low in salt to begin with.