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Water Now More Awesome Than Previously Thought
Dan writes "Wired has a great article about a guy who thinks we can provide unlimited energy , accelerate crop growth, desalinize and purify drinking water, obtain health benefits and provide air conditioning, all by pumping up water from the depths of the ocean."
OTEC, as a concept, has been around for quite some time. Prototypes have been built and tested around the world. Old news!
Actually Cornell University is cooled by Lake Source Cooling, and Lake Cayuga, while the biggest finger lake and fairly deep, is nothing all that special. Cornell was able to successfully cut its emissions and energy usage by about 90% with this thing, with no ill effects to the lake. I say that because some locals thought that it would kick up sedament which would cause eutrophication, but this never occurred. Also, people were worried that the warm water being dumped near the surface would impact the lake, but measurements showed that you can't even tell the difference in temperature more than 10 feel away. All in all, it was a really good move by the university. My only regret is that my freshman dorm wasn't hooked up to it so I didn't have any AC in the summer!
If this technology is going to be so successful why isn't being tried all over the place?
Because there are only a few islands throughout the world where it's practical. If you have a continental shelf, it ain't gonna work.
http://www.ocees.com/
The efficiency of these system is extremely low because the temperature difference is so miniscule. For thermodynamic efficiency purposes temperatures are measured in Kelvin and temperature differences are only a few percent. The maximum efficiency of these plants in an ideal world is only 6%. When you account for the very large amounts of energy needed to pump huge volumes of water, the real efficiency is only 2-3%. This FAQ covers this and other issues.
Yes, you can get energy, but not much.
Two wrongs don't make a right, but three lefts do.
It was the same guy! He's almost 80...
You need to read the facts on the technology, go here:
http://www.ocees.com/
About the sweating of pipes, it sounds a lot like
g ation_History.htm
drip irrigation, pioneered some Israeli.
It's been around since, what, the mid 60's?
Oh, found information:
http://www.netafim.com/About_Us/NETAFIM_Drip_Irri
http://en.wikipedia.org/wiki/Drip_irrigation
Lessee, water converts to steam and might break down, but odds are will recondense into... water. So where are we depleting this source? And if it's temperature, remember that heat rises, so by default (and by convection) this water is its own heat sink.
This sig no verb.
Hydrothermal events (http://en.wikipedia.org/wiki/Hydrothermal_vent) exist in the oceans and pump out water at temperatures very close to, if not, at boiling temperatures. Pumping warm water back into the ocean is not going to make that much of a difference on the oceans.
>>pseudo-scientific, completely unfeasible, sketchy "unlimited energy" solutions
I'm sure they said the same thing about the internal combustion engine. Thanks for your complete lack of vision.
Just think for a moment what a clean source of power this could be. Stirling engines (external combustion engines) are quire remarkable little machines which extract power from a thermal delta. Hook a deepsea cold water supply to a Sterling engine and you'd have an extremely reliable, zero-pollution source for reciprocal motion or electricity generation. And the hotter the climate, the more effective it would be due to the greater thermal delta. Wouldn't you call a zero-emission engine be a desirable product?
I think he is counting on inertia, or some more subtle effect I can't think of.
The articale mentions that once the system is primed, it takes very little energy to keep pumping.
Think about it. You're not pumping water up into the air, you're pumping water above other water. Without any pumping, the water will automatically lift the water to, you guessed it, sea level. You only neet to lift it the extra 30 feet to your beach side farm.
Getting the system started probably takes a lot of power as you have to get all the water in your pipe moving fast enough so the water won't warm up by exchanging heat with the outside water, but one it's moving, inertia will help you keep going. You only need to make up for friction, and for the fact that cold water is slightly less dense.
Then again the article mentions that the pipe acts like a siphon, so maybe there is some other effect I can't think of. Maybe the decreased pressure because of the pump makes water freeze and therefore rise? dunno.
For all you Engineering Types, here is a page with an animation which shows the basis for the technology:
http://www.ocees.com/mainpages/Powersystems.html/
It's not untouched by man. From shipwrecks to dumping of garbage to all the usual pollutants, the deep-ocean is most certainly affected by our presence already. Of course, there's nothing new about this, it's just harder to tell when you can't actually visit most of this stuff in person, and have to send ROVs.
As far as benthic thermal pollution, it already exists in the form of deep ocean thermal vents. Of course these are natural, even though they spew vast amounts of sulphur etc. I would suspect the ecosystem down there would handle this pretty well, since by the time the warm water got back down it would be nearly the same temperature as the surrounding water.
Of course, it would be wise to run a full-scale test for a few years to determine the localized impact on the biosphere,(before widely deploying it) but I wouldn't jump to any conclusions until we see the findings.
m-
You catch enchiladas by picking them up behind the head and holding them underwater until they don't kick anymore -VeGas
That's what I assumed at first, too. But according to TFA it allegedly sustains itself like a siphon. It's mostly a one-time problem to get the flow started, I guess... then the siphon does most of the work. (Presumably with some level of ongoing pump assistance.)
If true, that is a truly neat hack.
With reasonable men I will reason; with humane men I will plead; but to tyrants I will give no quarter. -- William Lloyd
The idea that you are getting all this freshwater "free of charge" is wrong. All sweating pipes are is rain by another name. If you pull enough water out of the air to supply the water needs of California's farm irrigation, then you have pulled water out that would have rained down upon Arizona (for example).
So now you create even more drought inland in order to supply the needs of the coasts. As a resident of the inlands, <sarcasm> thank you oh so very much!</sarcacm>
www.eFax.com are spammers
The idea has been around a long time but then so has John Craven. Toronto is using the waters of Lake Ontario to provide air conditioning for a big slice of downtown realestate. The big problem with the Great Lakes is the needs of the urban sprawl that circles the Lakes' shores is putting stress on the resource, not to mention the political fray ensuing from many plans to alter the in/out flow of the watershed feeding the lakes. Being Canadian and watching the growing need for water in the US just makes me feel like we're gonna be on top of the quality of life index for a long time to come.
"Academicians are more likely to share each other's toothbrush than each other's nomenclature."
Cohen
The same sort of thing exists in Toronto.
http://www.ocees.com/mainpages/Powersystems.html
See http://www.enwave.com/enwave/dlwc/
Anyone who has been to Dubai (I spent a few years there) knows that desalinization in such large capacities is both financially and technically sustainable... Irigation is a no brainer... Creating surplus energy, though ??? That does not sound plausible...
Use a Metal Halide light, control the ph level, user good soil and water when needed and you'll get three batches sans cold ocean water.
Too bad there's not enough water on the planet for this to happen, huh?
-py
The water that is being pumped is not creating any energy. The heat/lack of heat in the water being pumped is generating the energy. That heat is provided by the Sun. Its not a perpetual energy machine, nor is it portrayed as one, unless that is, you didn't read the entire article. Its no more of a perpetual energy machine than motorized solar panels that use the energy they create to drive the motor that swivels them to track the sun.
There is a global circulation system called "Thermohaline Circulation". Basically some amount of water, North Atlantic Deep Water (NADW), sink around Labrador Sea, due high salinity and low temperature, until sea bottom (or almost there) and then spread around the world following the Stommel-Arons model.
Due mass continuity, some amount of water must source that water and this is made by surface water, which is much warmer than that cold deep water. So, North Atlantic export cold water and import warm one, which means a positive heat balance. Without that, North America and Europe should be colder than they are now. Some people would call that "Climate Changes"! ;)
P.S.: This is only part of the story, where I neglect some "details".
I have never heard of an "ocean engineer," as opposed to chemical engineer or electrical engineer.
Ocean Engineering is a field of civil engineering, which is concerned with construction on coasts or under water. Offshore oil rigs are designed by Ocean Engineers, for example.
-jcr
The only title of honor that a tyrant can grant is "Enemy of the State."
The turbine produces electricity to lower the pressure in the chamber. The warm water loses energy when spins the turbine. If the water loses enough energy, there may be some electricity to power other things.
Club soda is carbonated, right? (So any softdrink would do).
Because of the carbon in the mix, the freezing temperature of club soda is lower then zero. So when you pour it, the less-then-zero temperature liquid hits water, dropping the water to less then zero, and freezing it. Additionally, as you pour, the carbon gas escapes, until the freezing point rises to match the current temperature, and bam, frozen liquid.
I'll have to try that when I get home, sounds really neat.
Look, I've taken few thermodynamics classes and I know what you are talking about. The theory is fine and dandy. You have lots of energy in that water. The problem is, it's next door to useless because that 15 degree difference is not enough to make a practical power plant (one that can produce enough energy to make its construction worthwhile).
The equation for Carnot cycle efficiency is nu = 1 - Tlow / Thigh [in kelvin]. This is about 5% for a 15 degree temperature difference. After you take inefficiencies into account, this will become maybe 1%. What this boils down to is that you need a enormous, extremely expensive plant to produce laughable amounts of power. On top of that, you get into many technical problems related to pumping seawater. It's corrosive and has lots of nasty wildlife in it (shells, etc.) which quickly clog up your pipes, heat exchanges, and other equipment. In short, this is one technology that is extremely unlikely to ever become practical.
it's not a siphon it's an inertial pumping system. once you start the flow of water, it's easy to sustain, and more electricity can be generated from the cold water than is used in pumping it to the surface. The problem with inertial pumping is that you never want to Stop pumping water, because the energy required to start it back up is so much greater. if you're in a warm enough climate, that's fine, but in colder climates like the midwest there are going to be 'complications' in using such an 'always on' system in the spring, fall, and winter.
In those places it's more pratical to use the cold water for AC, rather than for electrical production, since it's seasonal, and you can always 'cool the outside air' if it's not warm enough to ac the building the whole time...
https://www.gnu.org/philosophy/free-sw.html
Craven is sort of crazy, but he is the real deal, at least when it comes to the Navy stuff. He wrote an excellent book , which was a good companion and response to another book that first unveiled his crazy greatness. He was the architect, or one of them anyway, of the Polaris missile system; which arguably helped keep the peace during the Cold War. ANyway, either book is a good read. He comes across as a stupendous smart guy maverick badass type in both.
Dude, I think I can see my house from here.
It is a siphon. It doesn't matter how far down the pipes go, all that matters is how far above the top of the ocean the water goes. All you have to do is build a ditch (below sea level) and then it (the atmosphere) will pump to there. Then you just have to move it from there. Well, there is some friction.
If I remember correctly, he was also the guy who sold the Navy on using guassian distribution techniques to find the S.S. Thresher when it went missing, and the lost nuclear bomb off Palomares Spain.
He was written about extensively in the book Silent Service (author eludes me right now).
Well, yes. Yes I have,,,
:-)
The poster's exactly right. Applying both ice and heat to an injury manage the circulation to the area.
When you have an acute injury, say, a sprained ankle, you get an inflammatory response -- swelling. That's nature's way of splinting and immobilizing the injury. That problem is that all that swelling later turns to scar tissue, in essence, crippling you afterwards.
What you're trying to do is to use cold to decrease circulation during the acute phase of an injury (to reduce swelling), and to use heat and motion to increase circulation during the chronic phase (to help break up scarring and create new muscle and bone). The rule of thumb is ice for the first three days, then heat, but really, you want to ice as long as there's heat coming off the injury.
Both ice and heat will make you feel better. In my experience, ice is initially less comfortable, but WAY more effective in the end. And, ice combined with Aleve is even better.
As an aside, ultrasound therapy works the same way as heat, albeit in a more focused and comfortable way. You never want to use it acutely, but for things like old hamstring injuries, it's the freaking bomb.
During rehab, (and frankly, if you're playing competitively, you're ALWAYS in rehab) you end up using both heat and cold. Usually, that's heat beforehand (to increase flexibility and circulation) and cold afterwards (to reduce inflamation from the trauma to old injuries). After a while, you just get used to the routine -- although spending a half hour with your balls in an ice whirlpool is never any fun.
No, I'm not a doctor or a physical therapist, but after a broken leg, a blown hamstring, one remaining ligament between two ankles, twenty five years in the cage, and a trip playing in the World Games, you get to know these things...
Long story short, it didn't work very well. My physics prof pointed out that the theoretical limit on their technology was
or about 10% where 303 is the boiling temperature in Kelvin and 273 the cold water temperature in Kelvin. After subtracting the various inefficiencies, there wasn't enough power left over to do anything with.All was not lost however, the Hawaiians ended up using the cold, nutrient rich water to feed aqua culture enterprises that would use it to grow lobster, abalone, kelp and nori (the seaweed you wrap sushi in.) Aqua culture was so successful that the farmers started sinking their own pipes because the state couldn't meet the demand for cold water.
They use an ammonia/water mixture for their working fluid, which presumably has a significantly lower boiling point. They might also apply a vacuum, which would also lower the boiling point.
-ccm
Too much Law; not enough Order.
Unfortunately for the Saudis, IIRC the Persian Gulf is very shallow.
It's like the old trick where you put a glass under water, then turn it upside down and lift it out of the water. Until you provide a way for the air to displace the water, like lifting it far enough out of the body of water, it can't escape.
Instead of a glass, think of it as a U shaped pipe rising up out of the water. There's still no way for air to get in. It only takes a little bit of power to circulate the water, because you've negated the effects of gravity.. the weight of the water pulling down on one side is almost (aside from differences in density) exactly the same as the weight of the water on the other side. You're essentially just pumping water on a level plane, which doesn't take much power. The fact that one side of the pipe is 7000 feet below sea level is mostly irrelevant, because the pipe enters and exits the ocean at sea level.
Obviously they can't dunk the facility underwater to fill the pipe, so they have to provide enough power to pump a few thousand gallons into the pipe to get it going.. that requires a substantial amount of power. I imagine this would have to be done every so often after they shut down the system for cleaning and maintenance though.
Incidentally, ships generate their potable water through a very similar process. The (relatively) cool seawater is pumped through pipes in a unit containing warmer air. The water condenses on the pipes, drips into the reservoir, and then it's filtered and used for drinking, bathing, and steam. The filters on these things need to be cleaned pretty often since all kinds of biological and mineral deposits form on the filters after even 1 day of use.
I imagine there will be several paths for the water to flow through filters, so they can shut off one and clean it without needing to shut down the whole system.
The only immediate drawback I see (living on one of the Marianas Islands myself), is that we're sitting on the edge of the ring of fire, and there tend to be quakes pretty regularly. Actually almost constantly at small levels.. the seismographic charts here are never flat lines. It's annoying to lose water due to a ruptured water main, but if one of these huge pipes were to crack, it could be catastrophic.
https://www.eff.org/https-everywhere
Okay, lets say for a moment that there are 6 billion people on the planet, and each one is going to consume 4 liters of ocean water every MINUTE for purpose of cooling, which would be like trying to cool yourself off by running a shower 24/7 at full blast. Then, considering that there are about 1.34x10^21 liters of ocean water in the oceans, this is about 0.001% of the ocean's water being cycled through in an entire year. And that's about as extreme as it could possibly get.
In reality, this would only be practical for a portion of the population, and so its usage would never reach this.
Correct. The grandparent poster should read the article and notice that nowhere did it say that the sweat irrigation was to be derived from buried pipes. It even went so far as to describe one of his PVC cold water pipe sweat condensers in detail, noting that it was out in the open.
t ml?pg=3&topic=craven&topic_set=
"Irrigation:
Pipes carrying cold water run beneath fields of crops, sweating freshwater to irrigate plants and chilling their roots, promoting faster crop cycles."
http://www.wired.com/wired/archive/13.06/craven.h
I browse at +5 Flamebait- moderation for all or moderation for none.
My father just finished building a house in Ky. of all places that uses a geothermal heat pump to reduce costs of heating/cooling. While he does not see 90% efficiency, he does see around 40-50% efficiency; a substantial savings in a house 4100 square feet in size. To put that in perspective, his heating/cooling costs are very close to mine while my house is about 1/3 the size of his -- 1400 square feet. The theories behind the ocean water pumps and his heat pump are very similar. You can find out more here.
Beware of he who would deny you access to information, for in his heart he dreams himself your master.
You are wrong on both counts. The temperature difference matters a hell of a lot more than specific heat.
Oh good, thank you for enlightening me. So, for example, you would assert that you can extract more energy from a kilogram of lead at 500C, than you could from a kilogram of water at 90C?
Dropping the lead to room temperature (22C) requires it to lose 61.7KJ. Dropping the water to room temperature requires it to lose 284.6KJ.
Without your tremendously informative commentary, I simply would not have realized that 61.7 > 284.6. Thank you, kind sir, for revealing this secret to me.
As far as climactic change: bullshit. You won't change the temperature of the ocean by even 0.1 degrees this way. All you are doing is mixing the water.
I don't really expect you to understand this, but mixing matters far more than mean temperature, in this case. According to some models (R X Huang, "Mixing and energetics of the oceanic thermohaline circulation", JPO, 29:-746, 1999, for example), the rate of thermal mixing contributes as one of the LARGEST sources of global climatic change, and (other than Coriolis effect) singlehandedly determines where and how fast surface ocean currents will flow.
But then, you've probably never heard of that whole "gulf stream" thing, preferring to study the Bible for your weather reports.
So, that's why an American's life expectancy at birth is 77.71 years while a Canadian's is 80.1? Who the fuck modded this bullshit up?
CIA World Fact Book:
Can
US
Everyone seems to be missing the point.
1) You pump the water up, using a lot of energy.
2) You circulate that water around in various heat exchangers, but it *never leaves the pipes* and is never exposed to anything.
3) The water goes back down - recovering almost all of the enrgy required to get it up, only losing the friction costs.
So, all you've done is warm the water up a bit, and use a little energy to overcome friction.
Here in New Hampshire, we have to wait for the soil to warm before putting tomatoes in the ground. Planting them in April instead of June assures the loss of about a month of growth. Maybe cool soil is OK deep in the tropics, but I doubt that it helps in temperate regions.
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I think we can all agree that Carnot says the thermodynamic efficiency of this method is never going to be more than 10% even in optimal circumstances, and the mean theoretical efficicency is probably 5% or thereabouts (assuming 4 C water from the depths and mean hot-side temperature of 20 C). But that doesn't mean the technology is unworkable or impractical.
The heat capacity of water is 4186 J/kg*K, so 5% of the total energy available in a 16 K temperature difference is 3.3 kJ/kg. With a pipe diameter of 10 m and a flow velocity of 1 m/s (big pipes and low velocity is best, because head loss goes as v**2) you get 78 m^3 per second, or 78,000 kg/s, or an available power of about 250 MW.
If the practical efficiency is 1%, that would be 50 MW. So far, it doesn't sound very practical. But up the pipe diameter to 30 m, and we're looking at 0.5 GW. That's not bad.
30 m (~100 ft for the Yemeni's and Americans in the audience) may sound like an insanely large pipe, but humans have a long history of developing technology to insane extremes. It is not possible at this point to say whether this technology will be worth it in the long run, but the raw numbers don't look sufficiently bad to write it off just yet.
--Tom
Blasphemy is a human right. Blasphemophobia kills.