Slashdot Mirror
New Rechargeable Battery Uses Water
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."
so does the one in my lawnmower, I thought lead acid batteries have been around a while, maybe I just live in the future
Wow, two fallacies in one!
A sweeping generalization AND a stunning ignorance of the hydrologic cycle.
Well done good sir, well done *slow clap*
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
It's gizmag ... Prepare to be annoyed with ads
Pulsed Media Seedboxes
Actually there are more than two. I counted four.
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...
A pox on web designers who feel that window.innerWidth == screen.availWidth
actually fresh water is a bit scarce in some places, such as UAE & there abouts. But yeah... Not exactly that scarce :)
Pulsed Media Seedboxes
I purchased a Water Powered Clock 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.
Like, recharging your flashlight at the urinal.
Gently reply
Should I stop holding my breath for microbial fuel cells? http://news.nationalgeographic.com/news/2005/09/0909_050909_cowbattery.html
Glad I could help.
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.
Jules Verne strikes again!
We could use the generated electricity to power desalinisation plants.
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
But i think the Norwegians beat us all to it:
http://www.statkraft.com/energy-sources/osmotic-power/
Why are other peoples sig's always more witty ???
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!
This sounds like something that would just finish off the migrating salmon population if implemented.
Im getting a sort of deja vu feeling because i'd swear i've heard of this, or a similar, process before.
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.
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.
Is it just my observation, or are there way too many stupid people in the world?
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.
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.
It's a good thing that Standford isn't in the UAE then.
Every time I start to have faith in humanity, I ruin it by driving to work between 7 and 8 am.
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.
From TFA:
So potable water isn't necessarily needed.
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.
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 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.
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.
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.
Shutting down free speech with violence isn't fighting fascism. It IS fascism!
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
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:
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...
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.
My first thought was they build a desalination plant right next door that operates off hydro or solar power.....
who needs fresh water when you can use pee ?!!!
the preceding comment is my own and in no way reflects the opinion of the Joint Chiefs of Staff
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.
Information theory is life. The rest is just the KL divergence.
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!
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?
Isn't the chlorine the material that is exchanged? Not the actual electrodes?
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.
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.
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.
Isn't the chlorine the material that is exchanged? Not the actual electrodes?
Indeed, you are right. Both electrodes absorb salt ions: 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...
I'm sorry, but how?
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.
My first thought was they build a desalination plant right next door that operates off hydro or solar power.....
Solar may be plausible...but I think there's a major flaw in the idea of a hydro-powered desalinization plant: places that have enough flowing river water for hydro don't need desalinization plants.
Momentarily, the need for the construction of new light will no longer exist.
The same way roads and all other government projects are funded.
Excluding the UAE, most of the middle east could easily fund such projects with a tax on exported oil. Not all UAE nations export enough oil, so they could then have their various sheiks pay for it. Desalination is a well understood technology.
Truthfully though, these nations have other problems perhaps even more pressing. By that I mean the political issues that have created the current situation to begin with.
i'm not sure personally but i have a feeling that if they focus their interest in providing fresh water rather than other crap
http://www.dailymail.co.uk/sciencetech/article-1094797/Worlds-refrigerated-BEACH-built-luxury-hotel-Dubai.html
just an example.... i'm sure if they refocused their efforts they could solve the problem.. but again its all about priorities.
'...if only "Jumping to a Conclusion" was an event in the Olympics.'
Like reverse osmosis - in reverse ;)
I said you can extract if faster than it is replinished, but it really is inexhaustable. You will not run out. Once the reserve is gone, you can only get it as fast as it seeps down, but it isn't *gone*
The point of the post was that people are far too accepting of the concept that *everything* is scarce. Water just isn't one of those things.
The planet will not run out of water. It just isn't going to happen. Sure, we might have to move usage around a bit in some cases, but the idea that water will magically disappear is preposterous.
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.
Well... no. You might say that technically the water does "cease to exist as water" since photosynthesis converts water and CO2 into sugar and oxygen. But combustion of the sugar converts it back into water and CO2, so the water is just locked up temporarily until the sugar is metabolized. It will eventually make it back into the water cycle. Water is a very, very stable molecule, and sugar is not (if it was, it wouldn't be a very good fuel).
Sometimes it's best to just let stupid people be stupid.
Ewww, you mean I'm drinking dinosaur piss?
If you've ever had tap water from a town along the Mississippi River, you're probably drinking some thousands of other humans' piss. Possibly even you own, if you drive south along the river. Towns on big rivers don't drill for water. They treat the river water for drinking, then treat the sewage and release it back into the river.
I remember as a kid I had a Captain Planet Water Wristwatch. It used TAP water to make electricity.
NOT REALLY NEW
The water won't be *gone*, but once it's left the aquifer and flowed into the sea it's a heck of a lot less useful than when it was back in the aquifer. Also, it depends on your opinion on what counts as "replenished", the Nubian Sandstone Aquifer System under the Sahara for example ain't going to be replenishing any century soon.
Desalination is far from solved (as an economically viable technology). Yes, it works well for cruise ships and the like, but providing clean water to 10s of millions of people living in poverty? Not really. The best method for desert dwellers is to tap into fossil water supplies. Gadhafi (yes, that Gadhafi) put $30b into a water distribution and supply system that tapped into fossil water wells in the main desert and supply it all over the country. The only problem is that fossil water wells do not regenerate as fast as we use them and suffer the same fate as oil; cost goes up as more water comes out because the levels go down and it becomes harder to pump. These sources are not a permanent fix and $30b is a LOT of money for a lot of countries. Importing water isn't easy either. Water weighs a lot and costs a lot to import and, remember, we are talking about countries with millions of people with next to no GDP. Unfortunately, you are using a very wealthy nation as your example, but I'm talking about the Chads, Sudans, Nigers of the world, not the Dubais and Saudi Arabias.