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New Rechargeable Battery Uses Water

samzenpus posted more than 2 years ago | from the I-want-my-water-engine dept.

Power 179

fergus07 writes "Scientists at Stanford have developed a battery that uses nanotechnology to create electricity from the difference in salt content between fresh water and sea water. The researchers hope to use the technology to create power plants where fresh-water rivers flow into the ocean. The new 'mixing entropy' battery alternately immerses its electrodes in river water and sea water to produce the electrical power."

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179 comments

ALready an energy shortage there. (-1)

Anonymous Coward | more than 2 years ago | (#36034870)

Considering how many rivers aren't even making it to the sea any longer (like the Colorado), I don't see this as a long term or viable energy source. Fresh water has become too precious for energy.

Re:ALready an energy shortage there. (2, Insightful)

Anonymous Coward | more than 2 years ago | (#36034944)

Wow, two fallacies in one!

A sweeping generalization AND a stunning ignorance of the hydrologic cycle.

Well done good sir, well done *slow clap*

Re:ALready an energy shortage there. (0)

Anonymous Coward | more than 2 years ago | (#36035016)

Actually there are more than two. I counted four.

Re:ALready an energy shortage there. (0)

Anonymous Coward | more than 2 years ago | (#36035144)

There is such a demand for fresh water that many many rivers around the World aren't flowing into the sea -which this technology is dependent upon. And as the World's population increases, this problem will continue.

It's also interesting to note that potable water is becoming increasingly scarce around the World.

*Slow clap* indeed.

Re:ALready an energy shortage there. (1)

wjousts (1529427) | more than 2 years ago | (#36035438)

From TFA:

In fact, the fresh water doesn't have to come from a river. Cui says that storm runoff, gray water, or even treated sewage water could potentially be used. As an added benefit, the mixing entropy process can be reversed to produce drinking water by removing salt from ocean water.

So potable water isn't necessarily needed.

I'm surpised nobody has noted this alternative (1)

Thud457 (234763) | more than 2 years ago | (#36035858)

who needs fresh water when you can use pee [gizmodo.com] ?!!!

Re:I'm surpised nobody has noted this alternative (1)

kheldan (1460303) | more than 2 years ago | (#36036106)

who needs fresh water when you can use pee ?!!!

This comment sponsored by Bear Gryllis

Re:ALready an energy shortage there. (3, Informative)

Ferzerp (83619) | more than 2 years ago | (#36034964)

Wait, you actually think water is disappearing, going poof? Where do you think this water is going? Water is not something you use up and then there is no more. You see, it evaporates, and then it rains down again clean. Now it may not be where you expected it would be, or it may end up unfit for use in areas with contaminants, but the water is still there.

You realize there are nearly inexhaustible supplies under the ground right? If you suck it out faster than it seeps back down, guess what, the water still exists. We could potentially use it faster than we harvest it, but to assert that water is a scarce resource is very, very misleading. You can always expand your collection techniques.

Or are you suggesting we are in danger of locking up *all* of the hydrogen and oxygen on the earth in to other compounds?

Oh, you know that salt water? Let it evaporate, and magically you have more fresh water. :P

Re:ALready an energy shortage there. (1)

Skal Tura (595728) | more than 2 years ago | (#36035034)

actually fresh water is a bit scarce in some places, such as UAE & there abouts. But yeah... Not exactly that scarce :)

Re:ALready an energy shortage there. (1)

h4rr4r (612664) | more than 2 years ago | (#36035488)

They could easily have free/nearly so fresh water for everyone, but those areas are generally run by less forward thinking leaders. Recently there has been some move to change that, but seems to have tapered off.

Re:ALready an energy shortage there. (1)

tnk1 (899206) | more than 2 years ago | (#36035348)

What they didn't tell you is that the process actually involves Ice-9, so yeah, we're going to use up all the available liquid water and then die.

Cool battery though.

   

Re:ALready an energy shortage there. (0)

Anonymous Coward | more than 2 years ago | (#36035432)

He's saying that fresh water is more valuable for agriculture than for energy production. You're saying it's possible to get fresh water at a higher price-point if it's not available at a lower price-point, but that doesn't change anything -- the new water will still be preferably used for agriculture.

Re:ALready an energy shortage there. (4, Interesting)

gr8_phk (621180) | more than 2 years ago | (#36035502)

I think he's talking about taking water and sending it to Arizona where it then evaporates in the desert and doesn't actually make it to the end of the river. I'm guessing of course. But as for these "inexhaustible" supplies under ground, you should read about the supply in the midwest [wikipedia.org] which requires drilling to new depths because it is being depleted. Should you think going deeper is always an option, you may want to read the recent stuff of fracking to see how the deeper water is being deliberately contaminated. There are solutions to these, problems, but what we are doing vs what we could be doing don't really match.

Re:ALready an energy shortage there. (1)

pla (258480) | more than 2 years ago | (#36035650)

Wait, you actually think water is disappearing, going poof? Where do you think this water is going?

You might want to Google "photosynthesis". Major rivers no longer reach the ocean because we've diverted them for use in industrial agriculture. And yes, that water really does cease to exist as water.

Of course, realistically, most of it ends up going to waste, either soaking into the ground or evaporating; Yes, we can theoretically reduce those losses drastically, but as it stands, for both human consumption and TFA's electrical generation purposes, we no longer have access to that water in any meaningful, useful way.

Re:ALready an energy shortage there. (1)

seededfury (699094) | more than 2 years ago | (#36035736)

My first thought was they build a desalination plant right next door that operates off hydro or solar power.....

Re:ALready an energy shortage there. (1)

Candid88 (1292486) | more than 2 years ago | (#36036550)

Ground water isn't a closed system in any sense. If water is taken from an aquifer at a rate greater than it is replenished then the level of the aquifer will fall and even temporarily dry up until the water levels can replenish, this could take a months, years or even centuries dependent on local geography and climate.

In many places, aquifer depletion is a major engineering obstacle necessitating boreholes to be drilled ever deeper to maintain their rate of water extraction until the point they are simply no longer economic to operate and a new aquifer must be found.

yea (1)

Osgeld (1900440) | more than 2 years ago | (#36034902)

so does the one in my lawnmower, I thought lead acid batteries have been around a while, maybe I just live in the future

Re:yea (0)

Anonymous Coward | more than 2 years ago | (#36035224)

salty water in a lead acid battery?

Re:yea (0)

Anonymous Coward | more than 2 years ago | (#36035268)

Who said anything about lead acid batteries ?

Great News for Environment! (1)

0xG (712423) | more than 2 years ago | (#36035032)

The mixing entropy battery could be used to build power plants at estuaries where fresh water rivers join the ocea

Never mind that river estuaries are perhaps the most environmentally sensitive areas on the planet...

Re:Great News for Environment! (2)

snookerhog (1835110) | more than 2 years ago | (#36035090)

I would gladly trade this for the aging coal power plant that currently sits on the banks of my local estuary. I am inclined to believe that this will be better for my local environment than the coal burning.

Re:Great News for Environment! (3, Informative)

wjousts (1529427) | more than 2 years ago | (#36035472)

From TFA:

Because river deltas and estuaries are sensitive environments, the Stanford team designed their battery to have minimal ecological impact. The system would detour some of a river's flow to produce power, before returning the water to the ocean. The discharge water would be a mix of river water and sea water, and released into an area where the two waters already meet.

Re:Great News for Environment! (0)

Anonymous Coward | more than 2 years ago | (#36035778)

Ah, so we only rape the environment a little bit. I'm sure she'll be OK with that.

Hurray for environmentalists (1, Insightful)

DNS-and-BIND (461968) | more than 2 years ago | (#36035656)

Ever wonder why environmentalists have such a bad name? Here's a new concept and they're already shooting it down, based on nothing more than a vague assertion.

Re:Hurray for environmentalists (0, Troll)

hedwards (940851) | more than 2 years ago | (#36035848)

Environmentalists have a bad name because the industries that are doing all the damage find character assassination easier than actually cleaning up their mess. And much of the anti-environmentalist movement is made up of people that believe that God would never allow for more flooding because the Bible doesn't say anything about another great flood. Or are so self centered as to think that they don't have any sort of social responsibility for the next several generations.

Re:Hurray for environmentalists (1)

DNS-and-BIND (461968) | more than 2 years ago | (#36036026)

Well, that certainly excuses relentless negativism and theophobia. Well-played! Please continue the campaign of shitting all over solutions.

Re:Hurray for environmentalists (2)

ep32g79 (538056) | more than 2 years ago | (#36036344)

Environmentalists have a bad name because the industries that are doing all the damage find character assassination easier than actually cleaning up their mess.

Rigggght.... It's all a big conspiracy against environmentalists perpetrated by the big bad corporations. Environmentalists [huffingtonpost.com] have [oregonlive.com] never [pipefinders.com] done [dailymail.co.uk] anything [breitbart.com] to [katu.com] damage [wordpress.com] their [seattlepi.com] own [santacruzsentinel.com] character [stuff.co.nz]

Re:Great News for Environment! (0)

Anonymous Coward | more than 2 years ago | (#36035664)

Never mind that river estuaries are perhaps the most environmentally sensitive areas on the planet...

From the TFA:

"Because river deltas and estuaries are sensitive environments, the Stanford team designed their battery to have minimal ecological impact. The system would detour some of a river's flow to produce power, before returning the water to the ocean. The discharge water would be a mix of river water and sea water, and released into an area where the two waters already meet."

It can also run using storm run off or treated waste water. Any other concerns that were clearly already addressed?

How long will they last? (0)

Anonymous Coward | more than 2 years ago | (#36035054)

I purchased a Water Powered Clock [thinkgeek.com] a few years ago and it stopped working after about a month. Hopefully this technology has progressed and these batteries will have a decent lifespan.

Re:How long will they last? (0)

Anonymous Coward | more than 2 years ago | (#36035312)

At least you know exactly when it died

Think Smaller (3, Funny)

retroworks (652802) | more than 2 years ago | (#36035072)

Like, recharging your flashlight at the urinal.

Re:Think Smaller (1)

Abstrackt (609015) | more than 2 years ago | (#36035204)

As a Slashdotter, I find I get more value out of one of those flashlights you have to jerk back and forth to build up a charge. ;)

Re:Think Smaller (0)

Anonymous Coward | more than 2 years ago | (#36035362)

Yeah but when you use those it isn't light coming out of the "flashlight"

Re:Think dick. (0)

Anonymous Coward | more than 2 years ago | (#36035952)

As a Slashdotter, I find I get more value out of one of those fleshlights you have to jerk back and forth to build up a charge. ;)

Charge ahead!

Re:Think Smaller (1)

Five Bucks! (769277) | more than 2 years ago | (#36035206)

I have a flashlight with the dynamo that charges when you shake it. So I just charge it when I... well it's personal - but my light is always charged.

Re:Think Smaller (0)

Anonymous Coward | more than 2 years ago | (#36035608)

You're thinking too small!

Re:Think Smaller (3, Funny)

Inda (580031) | more than 2 years ago | (#36035770)

Next week on Slashdot:

New lemon orchard used to power city.

Clever academics have found a way to harness the power of a standard lemon with an old copper penny and some scrap zinc. Could this scale?

Re:Think Smaller (0)

Anonymous Coward | more than 2 years ago | (#36036298)

You spelt fleshlight wrong. Also: Ewwwwwwwwwww!

Re:Think Smaller (1)

DigiShaman (671371) | more than 2 years ago | (#36036638)

I would say to recharge the automatic flusher, but the flow of in-comming water already does that.

Is the start up called Nemo? (0)

Anonymous Coward | more than 2 years ago | (#36035156)

Jules Verne strikes again!

Just think of the possibilities! (5, Interesting)

naich (781425) | more than 2 years ago | (#36035186)

We could use the generated electricity to power desalinisation plants.

Re:Just think of the possibilities! (5, Interesting)

ShanghaiBill (739463) | more than 2 years ago | (#36035336)

We could use the generated electricity to power desalinisation plants.

I think you are trying to be funny, but this actually makes sense, and there are proposals to do exactly this. Here is how it works:

  • Step 1: Concentrate brine in large evaporation ponds
  • Step 2: Generate electricity from the osmotic difference between this brine and normal seawater
  • Step 3: Use the electricity to split seawater into fresh water and brine
  • Step 4: Recycle the brine back into the evaporation ponds
  • Step 5: Profit!

The reason this works is that you are effectively collecting the solar energy that shines on the evaporation ponds.

Re:Just think of the possibilities! (3, Interesting)

trout007 (975317) | more than 2 years ago | (#36035584)

Not that this would be ecologically feasible but what if you dug a tunnel from the pacific ocean to death valley (-300 feet). Then you could get some power out of the potential water drop. Then as the water floods the valley it's so hot it would evaporate and you could keep letting the water in. The evaporated water would rain on the next mountain down wind and create arable land.

Re:Just think of the possibilities! (0)

Anonymous Coward | more than 2 years ago | (#36035714)

This has been proposed for the Quattara Depression in the Sahara. Larger and easier to reach than Death Valley - and the evaporation might water the Sahara.

Re:Just think of the possibilities! (0)

Anonymous Coward | more than 2 years ago | (#36035836)

And you can sell the salt as some "gourmet brand" since it'll have a delightful mix of oceanic and desert flavors!

Re:Just think of the possibilities! (1)

DriedClexler (814907) | more than 2 years ago | (#36036092)

Probably be more feasible for Mediterranean -> Dead Sea, but then you'd have to tunnel through numerous archaeological sites to do it.

Re:Just think of the possibilities! (2)

MoonBuggy (611105) | more than 2 years ago | (#36035642)

Interesting, but what's the advantage of this over condensing the vapour from the pools directly?

Re:Just think of the possibilities! (1)

ShanghaiBill (739463) | more than 2 years ago | (#36036316)

Interesting, but what's the advantage of this over condensing the vapour from the pools directly?

It is orders of magnitude less expensive. If you want to condense the vapor, you first need to collect the vapor. Evaporation ponds typically cover thousands of hectares. Building an enclosure to collect the vapor over such an area would cost megabucks or even gigabucks. Once you collect the vapor you need to compress and cool it to turn it into liquid water. This is also very expensive.

If simply evaporating seawater was a cost effective way to produce fresh water, the world would have not water shortages, and the deserts would bloom.

Re:Just think of the possibilities! (1)

pr0nbot (313417) | more than 2 years ago | (#36035666)

Isn't Step 1 already splitting seawater into fresh water and brine?

Re:Just think of the possibilities! (1)

mcavic (2007672) | more than 2 years ago | (#36036054)

Isn't Step 1 already splitting seawater into fresh water and brine?

Yes, but you have to start with a pool of brine, to prime the pump.

Re:Just think of the possibilities! (0)

Anonymous Coward | more than 2 years ago | (#36036314)

We could use the generated electricity to power desalinisation plants.

I think you are trying to be funny, but this actually makes sense, and there are proposals to do exactly this. Here is how it works:

  • Step 1: Concentrate brine in large evaporation ponds
  • Step 2: Generate electricity from the osmotic difference between this brine and normal seawater
  • Step 3: Use the electricity to split seawater into fresh water and brine
  • Step 4: Recycle the brine back into the evaporation ponds
  • Step 5: Profit!

The reason this works is that you are effectively collecting the solar energy that shines on the evaporation ponds.

Are you serious or just trying to be funny too??

It is much simpler just to use the fresh water in the first place and it, you know, doesn't try to violate the 2nd law of thermodynamics.

Re:Just think of the possibilities! (1)

Sir_Eptishous (873977) | more than 2 years ago | (#36036144)

From the article: "In fact, the fresh water doesn't have to come from a river. Cui says that storm runoff, gray water, or even treated sewage water could potentially be used. As an added benefit, the mixing entropy process can be reversed to produce drinking water by removing salt from ocean water."

Isn't this already in practice elsewhere??? (4, Informative)

dr.Flake (601029) | more than 2 years ago | (#36035212)

I know the plans to put one of these into service are almost finalized in The Netherlands, spanning the "afsluitdijk"
http://wikimobi.nl/wiki/index.php?title=Zoet/zout_watergrens [wikimobi.nl]

But i think the Norwegians beat us all to it:

http://www.statkraft.com/energy-sources/osmotic-power/ [statkraft.com]

Re:Isn't this already in practice elsewhere??? (2)

arielCo (995647) | more than 2 years ago | (#36035450)

Depends on how wide your definition of "this" is. Let's quote TFA for convenience:

Making electricity from the difference in salinity (the amount of salt) in fresh water and sea water is not a new concept. We've previously covered salinity power technology [gizmag.com] , and Norway's Statkraft [gizmag.com] has built a working prototype power plant. But the Stanford team, led by associate professor of materials science and engineering Yi Cui, believes their method is more efficient, and can be built more cheaply.

Re:Isn't this already in practice elsewhere??? (5, Funny)

wjousts (1529427) | more than 2 years ago | (#36035510)

...spanning the "afsluitdijk".

Cat just jump on your keyboard?

Bass Akwards! (3, Insightful)

CatsupBoy (825578) | more than 2 years ago | (#36035280)

After the battery is discharged, the salt water is drained and fresh water is added to begin the cycle again.

This is awesome, we can use up all our fresh water and would have an unlimited supply of salt water!

Re:Bass Akwards! (1)

Attila Dimedici (1036002) | more than 2 years ago | (#36035452)

You do know that there is an amazingly simple way to separate the salt from the water, right? It is called evaporation.

Re:Bass Akwards! (3, Insightful)

CatsupBoy (825578) | more than 2 years ago | (#36035530)

You do know that there is an amazingly simple way to separate the salt from the water, right? It is called evaporation.

The concepts of desalination are certainly quite simple, its the economics that are complicated.

Re:Bass Akwards! (1)

JSBiff (87824) | more than 2 years ago | (#36035776)

This certainly wouldn't be appropriate everywhere. But, consider the Mississipi River Delta. It's dumping massive amounts of fresh water into salt water anyhow.

It hardly seems like diverting a small percentage of the fresh water being dumped into the ocean by nature, extracting power from it as it gets salty, then dumping the brackish water from the power plant into the ocean, in any reasonable way reduces the fresh water supply, does it?

Or, do you propose that we completely dam up the Mississippi so we don't "use up" all our fresh water?

Re:Bass Akwards! (0)

Anonymous Coward | more than 2 years ago | (#36035882)

This is awesome, we can use up all our fresh water and would have an unlimited supply of salt water!

The problem is far worse than you can imagine. We are dumping literally billions [wikipedia.org] of tons of fresh water into the oceans each year. Pretty soon there will be nothing left!

how new is this? (1)

metalmaster (1005171) | more than 2 years ago | (#36035304)

Im getting a sort of deja vu feeling because i'd swear i've heard of this, or a similar, process before.

Just like a potato battery... (1)

Overzeetop (214511) | more than 2 years ago | (#36035340)

It looks like a potato battery (that we used to make little clock kits back in the 80s) or any galvanic battery dating back 100+ years, but with a tweak to get more out of it, implemented on a larger scale, and slapped with a "New and Improved, now with NANOTECHNOLOGY" sticker.

On a commercial scale? (1)

JSBiff (87824) | more than 2 years ago | (#36035716)

I think what's new isn't the basic science, but the R&D to try to scale this up to commercial size power plants?

Still, I can't help but think that at some point, this is going to create contention somewhere between some peoples' need for fresh water, and other peoples' need for electricity.

I guess the idea is that places like the Mississippi Delta where a lot of fresh water is just dumping into the ocean (and being "wasted") *anyhow*, it wouldn't hurt to put such a power plant.

Can we get a comparison to hydroelectric? (1)

chemicaldave (1776600) | more than 2 years ago | (#36035318)

The Stanford team has calculated that with 50 cubic meters (more than 13,000 gallons) of fresh water per second, a power plant based on this technology could produce up to 100 megawatts of power.

I can't find any facts detailing the flow of water through various hydroelectric dam turbines to compare to this, but 100MW from 50m^3/s seems very efficient.

Re:Can we get a comparison to hydroelectric? (0)

Anonymous Coward | more than 2 years ago | (#36035760)

Wikipedia says:
P = hrgk
where P is Power in kilowatts, h is height in meters, r is flow rate in cubic meters per second, g is acceleration due to gravity of 9.8 m/s2, and k is a coefficient of efficiency ranging from 0 to 1.

For three gorges dam, h=80.6 m, k = .9, and with the given 50m/s comes out to about 35.5 MW.

So yes, lots of power, almost 3 times as efficient as a modern hydroelectric and doesn't require a specific location with a large drop in height. But right now that efficiency is only calculated. We'll see what it's comes out as once you change the electrodes to something cheaper and take into account, pumping and everything else not needed in a hydroelectric plant.

Re:Can we get a comparison to hydroelectric? (0)

Anonymous Coward | more than 2 years ago | (#36036404)

A simple formula for approximating electric power production at a hydroelectric plant is: P = hrgk, where
        * P is Power in watts,
        * is the density of water (~1000 kg/m3),
        * h is height in meters,
        * r is flow rate in cubic meters per second,
        * g is acceleration due to gravity of 9.8 m/s2,
        * k is a coefficient of efficiency ranging from 0 to 1. Efficiency is often higher (that is, closer to 1) with larger and more modern turbines.
https://secure.wikimedia.org/wikipedia/en/wiki/Hydroelectricity

I did your Google search (and felt lucky). You do the math.

Also deep wells (2)

scharkalvin (72228) | more than 2 years ago | (#36035350)

In Florida most drinking water is obtained from wells. Deep wells tend to be brackish and require desalination of the water to be usable. It would seem then that a combination use of waste water and deep well water would work. Also the battery sounds like it acts as a desalination device during discharge so it might serve the purpose of both desalination and power generation.

Re:Also deep wells (1)

zpiro (525660) | more than 2 years ago | (#36035562)

From reading the article, you add fresh water first;
then salt water -- the saltier the better -- this stage giving you the power

Then you start the cycle over again, cleaning out and adding fresh water.

No desalination of water involved, unless creating more brackish water is what you want.

Bad news for those without excessive access to fresh water near the coast.

But would be interesting to know how clean the water needs to be -- tolerance for pollutants.

Re:Also deep wells (1)

Nidi62 (1525137) | more than 2 years ago | (#36035674)

In Florida most drinking water is obtained from wells. Deep wells tend to be brackish and require desalination of the water to be usable.

So that explains why Florida has some of the worst-tasting drinking water in the entire country.

The Silver Electrode is very expensive? (2)

davonshire (94424) | more than 2 years ago | (#36035668)

From the article:

"The Stanford scientists are currently working on modifications to get the battery ready for commercial production. For example, the silver electrode is very expensive, and they hope to develop a cheaper alternative."

I'm really at a loss on this. How expensive can a silver electrode be, if you're producing enough power to charge for it? Silver while pricey (currently ~ $39.00/oz) It's just a tad more expensive than Lithium (currently ~ $31.50/oz) and if this thing really worked. they'd pay for the silver they used in a very short order. 50Megawatt would be around $3000.00 / hr at just $0.06/kwh.

It's gotta be cheaper than building a power plant and running coal to it all day.

Just my 6 cents worth.

DS

Re:The Silver Electrode is very expensive? (0)

hedwards (940851) | more than 2 years ago | (#36035908)

Coal is less about cheap than it is about our war on the environment and rewarding corporations with the deepest pockets. In some places like Texas the coal power isn't any cheaper than other forms of power are.

Wouldn't this "leach" material from the electrodes (1)

ArsenneLupin (766289) | more than 2 years ago | (#36035704)

Wouldn't this "leach" material from the electrodes into the water?

Normally, batteries work by leaching material from one electrode into the water, while precipitating ions on the other. By draining the battery, you actually "consume" one of the electrodes. Recharging work if the process can be reversed.

However, if the electrolyte is changed between charging and decharging, effectively the manganese dioxide or silver ions dissolved are now gone, which has two effects:

  • pollution
  • electrode whose ions are gone cannot regenerate

It could work with ions naturally present in water (such as the sodium from the salt...). Unfortunately, however, a sodium electrode dipped in water would make a nice firework, but not a battery...

Re:Wouldn't this "leach" material from the electro (1)

leuk_he (194174) | more than 2 years ago | (#36036016)

Isn't the chlorine the material that is exchanged? Not the actual electrodes?

Re:Wouldn't this "leach" material from the electro (1)

ArsenneLupin (766289) | more than 2 years ago | (#36036442)

Isn't the chlorine the material that is exchanged? Not the actual electrodes?

Indeed, you are right. Both electrodes absorb salt ions [rsc.org] : chlorine is taken up by the silver electrode and sodium is taken up by the manganese dioxide electrode.

Hmmm, impressive how the manganese dioxide can stabilize the sodium, hehe...

Congrats, props from me (2)

DriedClexler (814907) | more than 2 years ago | (#36035888)

In learning about thermodynamics I had learned that, where there's a gradient, you can extract energy, be it a gradient of temperature, electrical field ... or even chemical concentration. But it's one thing to know it's theoretically possible, and another thing to actually pull it off in a way that extracts meaningful energy. Good work, scientists and engineers.

Consumables? (1)

RightwingNutjob (1302813) | more than 2 years ago | (#36036012)

Will this magic power plant at the side of the ocean require new electrodes/new electrodes every few hours because of pitting and erosion, just like normal batteries?

If it works ... (-1)

Anonymous Coward | more than 2 years ago | (#36036120)

some green conehead will probably complain about the quality of the water going into the ocean ( too salty, too munch entropy, too something ).

As always, it's a scale problem. (4, Informative)

tacokill (531275) | more than 2 years ago | (#36036206)

So, 13,000 gallons per second of fresh water flow and we can get around 100MW. Let's go on a math exercise, shall we?

The average combined cycle plant is (at a minimum) around 400MW. Not including co-gens, etc. Just normal power plants sitting out in the middle of nowhere. Fukishima is around 4900MW. Fukishima isn't really fair because it is, by any measure, a large nuke plant. But, 400-1200MW is not an unreasonable range for "typical" power plants in the US, regardless of the technology used (coal, nuke, combined cycle, direct fire, etc)

At 400MW, you are talking 52,000 gallons PER SECOND of water flow. That, by any measure, is a shitload of flow. At 1200MW, we are talking 156,000 gallons per second.

For comparison, I just looked up the flow rate of the Mississippi river at the high water dam near Lake Itasca. Going thru the Upper St Anthony's falls lock and dam, the flow rate is around 90,000 gal/sec [nps.gov] .

So for ONE reasonably sized power plant, you would need fresh water flow that is the equivalent of the Mississippi River.

As I said, it's a scale problem.

Re:As always, it's a scale problem. (1)

steelfood (895457) | more than 2 years ago | (#36036564)

In comparison, the hoover dam generates 2.08 GW, and niagara falls 2.4 GW. And in the most extreme case, the three gorges dam does 18.2 GW.

It may work on small scales, but it cannot compete with hydroelectric on a large scale.

Over time ... (1)

applematt84 (1135009) | more than 2 years ago | (#36036220)

Over time, wouldn't mixing fresh water with salt water throw off the balance and eventually kill marine life? I'm not a marine biologist, but this sounds like a bad and an idea that's not been well thought out.
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