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Electricity From Salty Water
BuzzSkyline writes "It's possible to produce energy by simply mixing fresh and salty water. Although chemists and physicists have long known about the untapped energy available where fresh water rivers pour into salty oceans — it's equivalent to 'each river in the world ending at its mouth in a waterfall 225 meters [739 feet] high' — the technology for exploiting the effect has been lacking. An Italian physicist seems to have solved the problem with the experimental demonstration of a 'salination cell' that creates power given nothing more than input sources of salty and fresh water. The researcher believes that this renewable, environmentally friendly energy source could be deployed in coastal areas and could provide another addition to the green-tech roster. A paper describing the technology is due to be published in an upcoming issue of the journal Physical Review Letters."
Quick! Grab all your salt shakers and run to the bathtub!
leather-dog muksihs
Blog: @muksihs
he key ingredient in a salt-water capacitor is "activated carbon," extremely porous carbon made from wood, coal, or coconut shells.
Gilligan could have lived well on that island.
So can we expect this to work in parallel with existing hydro power generation techniques?
I hope the Energizer Bunny owns water fins and a snorkel!
A device that gleans usable energy from the mixing of salty and fresh waters has been developed by University of Milan-Bicocca physicist Doriano Brogioli. If scaled up, the technology could potentially power coastal homes, though some scientists caution that such an idea might not be realistic.
Forget scaling it up. Put one such device in every fresh water toilet bowl.
Keep in mind desalination is
salt_water -> salt + water
whereas this reaction is
water + salt_water -> less_salty_water
You'll note that they're not exactly inverses of each other.
Don't bother. PETA and Greenpeace both called and said it'll kill too many endagered fish species.
While PETA and Greenpeace may have different definitions of "too many" than you do, balancing concern about impacts on fish stocks with concerns about energy is a perfectly reasonable thing to do, given that fish are part of our food supply (and food chain).
There's also issues like whether or not a given fresh water supply might have better uses.
Tweet, tweet.
It produces less (laws of thermodynamics are a bitch). But you point out an interesting way to describe it to people. i.e. It takes energy to desalinate sea water, this process is sort of like running desalination in reverse to generate energy.
The world is made by those who show up for the job.
Actually the technology was already available, and is to be used to power most the majority of homes in the Netherlands, including mine, if the proposal is approved:
http://ecoworldly.com/2009/03/08/saltwater-power-could-supply-energy-for-most-dutch-homes/
Or the original publication:
http://pubs.acs.org/doi/full/10.1021/es9004224?cookieSet=1
Too late, Exxon already bought the patent.
There are serious transportation issues with piping potable water from places where it is plentiful to places where it is needed. That's WHY we have a potable water crisis in some areas (especially the American Southwest) while we have no problem whatsoever in others (like the Northeast or the mouth of the Missisippi). In those places there's already huge amounts of water flowing into the ocean. This technology would allow that water that is already being mixed with ocean water to generate electricity in the process.
Also there are situations where water is not potable due to issues other than salinity, and for the purposes of this process might be considered "fresh" compared to saline water.
An interesting thing would be if this could be used to provide for cheap solar power - Some of the largest "solar power" we use today are salt concentration ponds - they don't provide electrical power BUT they do provide the function of separating salt from water in large solar ponds. It would be horrendously inefficient per unit of surface area, but the cost is so low that large surface areas could be achieved.
retrorocket.o not found, launch anyway?
PETA and Greenpeace both called and said it'll kill too many endagered fish species.
Dang it! I warned these people. Last month I sent them a letter:
Dear PETA,
While I love animals as much as the next guy, I'm sick and tired of your stupid press releases. You do more harm than good by making animal lovers seem rediculous to the general public.
Therefore, I have no choice but to make you reconsider your PR tactics. Starting next week, any time you issue a press release that does animals more harm than good, I'm going to the pet store, and buying a hampster. Then I'm going to take it out in the parking lot and hit it with a shovel.
Sincerely,
LocalMan57
If you RTFA (pardon me, I forgot this is SlashDot) the same effect can be gotten by mixing salt water with more highly salinated water (made by evaporating sea water - say, using a solar evaporation pool) or lightly polluted water (non-potable).
I could also venture a guess, based on the fact this is a solution postulated for coastal locations, that the process could also be sited at or near the mouth of a river - say one the empties into the sea or ocean? In that case only fresh water that was destined to end up mixed into salt water would be used.
...carrier dead.....
"Brogioli maintains that his salinity cell could be ramped up faster than other salination approaches and could be made as affordable as solar power in a decade or so."
As affordable as Solar in a decade? Solar's main problem now is it's cost!
One of the best places (potentially) to grow algae for biofuels is in the desert. You could pump seawater inland, and circulate it in pools. If you covered those pools with greenhouses (which could just be big clear balloons... or not-so-big ones, if you use arrays of small pools) and collected water they'd make you some fresh water, which could then be combined with incoming salt water to produce energy to help run the system, whether that would be the pumps, mixing devices which keep the pools circulating, or what ever else have you.
Another idea for the waste water produced from this process is to pump it inland and use it in the algae pools... so you can have coastal plants whose effluent is used to grow algae for carbon-neutral biofuels, and [optionally] to raise the water table in the desert.
"You're right," Fisheye says. "I should have set it on 'whip' or 'chop.'"
This would be a great way to power all those desalinization plants on the coast!
æeee!
Keep in mind desalination is
salt_water -> salt + water
Show me a single commercial example where this is the case.
Desalination is:
lots of salt_water -> lots of slightly_saliter_water + a little fresh_water
High rejection ratios help reduce the energy requirements as greater temperatures or pressures (depending on the method) are required for greater salt concentrations.
There have been other ways to extract salinization energy: http://en.wikipedia.org/wiki/Reverse_electrodialysis
These methods are even being used in test sites to generate power. Main problems are that there's a lot of crap in rivers that you need to filter out to get high efficiencies.
- Give a man a fire and he's warm for a day, but set him on fire and he's warm for the rest of his life.
It's osmotic pressure. You have salty water and pure water, and there's a force produced when they contact, because the ions in the saltier water are driven by entropy into the less-salty water.
The energy you're stealing is solar power: the sun heats the salty water, evaporating out pure water, that goes up into the clouds and then rains, forming the rivers of pure water.
This is just a convoluted solar power system. But then again, so is everything else: wind, gravity, and more distantly, nuclear and oil.
The main environmental issue would be interfering with fish migration, for the many (very economically valuable) fish that live in the sea but spawn in rivers, like salmon. Which, by the way, are near miracles from a biochemistry standpoint, since they live part of their lives in the sea, where they're fighting to keep those same ions out of themselves because sea water has about twice the ion concentration as animal tissue so they have to maintain a more pure internal environment, and then they swim into fresh water, where they have to fight to keep from bleeding all their ions out, since many streams have about 1/2 or less the ion concentration as animal tissue. There aren't that many animals that can manage it.
Nostalgia's not what it used to be.
You start sentences "I clubbed that thing" often enough to "have a saying" for it? :)
Get your own free personal location tracker
It isn't a water problem, it's a stupid people problem.
But people are mostly made of water, so now you have a stupid water problem...
My webcomic
Energy on the planet doesn't just SIT there doing nothing.
Of all the highly concentrated nonsense in your post, this is the highest peak of wrong-headedness.
Just to take a single example: what is the quantum efficiency of photosynthesis reactions?
Energy goes to waste all over the place--it would, amongst other things, be impossible to see if it did not! Nature is unbelievably wasteful. The very fact of the existence of oil and coal reserves is testament to this: those beds were all huge amounts of available energy at the time the dead plant matter was deposited. It did indeed "just sit there" on the surface for thousands of years as it accumulated before being buried.
Energy is "just sitting there" accumulating in peat bogs as I write this, freely available for some magic unicorns or something to come along and use it. I don't see any, do you?
Finally, your bizarre claim that any change to ocean temperature whatsoever is "enough to disrupt the ecosystem" will stand as a monument to the dangers of innumeracy for generations to come.
Blasphemy is a human right. Blasphemophobia kills.
Don't bother. PETA and Greenpeace both called and said it'll kill too many endagered fish species.
Fish? Oh, you mean sea kittens.
As such, any time we find a new source of power, you can damn well bet nature has gotten there first, and that our exploitation of said power will have negative consequences for the species already using it.
This sentiment of yours is dangerous in the sense that it is wrong yet rational enough that too many people could believe it.
Nothing was using the energy stored in uranium or oil until we got around to using it. And neither us nor any other creature is harnessing e.g. the energy of deuterium and tritium contained in seawater. Nothing is even using the energy of the sun shining on the desert.
Another problem with your idea: energy cannot be really "used", it can only be directed elsewhere. Sooner or later every form of energy will change into heat. We cannot stop this, but before it takes place we can transform energy into other forms to do something useful. Example: when the sun shines on the desert, it is converted to heat straight away. But when we put solar panels there, we can redirect a part of the energy to our homes and use the energy from the sun there, where in the end it will also be turned into heat.
I could go on about how humans are not artificial, but part of nature, but the main premise of your post is already invalidated so I'll stop.
Those who would give up liberty to obtain working drivers, deserve neither liberty nor working drivers.
That wont bother PETA at all. They have nothing against killing animals senselessly. They only get angry if you try to justify the death of the animal by using its fur or meat for something useful, but if you just throw it all out it's all good with them. http://www.petakillsanimals.com/