Harnessing Vertical Sea Temperature Gradient

Sterling D. Allan writes "Sea Solar Power Inc., run by three generations of James Hilbert Andersons, has developed a solar power technology that does not fluctuate with the weather, but is available constantly. Their solution is to harness the solar energy stored in the sea by tapping the thermal gradient that exists naturally between the surface and deep waters, using a reverse refrigeration cycle. The modeling and testing done by the Anderson family over three generations since 1962 predicts that the cost of energy generation through this method will be within a price range comparable to nuclear, coal, natural gas, and other contemporary grid power plants. Ocean Thermal Energy Conversion, or OTEC, was invented in 1881 by a French scientist, Jacques Arsene D'Arsonval. SSP should be ready to build their first full prototype 2-3 years from now."

Solar????

[Lifewish]

Aquethermal, if you please! It's only solar in the sense that all power on Earth apart from geothermal is solar.

Re:Solar????

[MarkPNeyer]

Nuclear power doesn't derive its energy from the sun.

Re:Solar????

[Lifewish]

I knew I missed something...

Incidentally, does the thought of messing around with oceanic temperature gradients bother anyone slightly? It's probably not on a scale nearly wide enough to destabilise any currents, but it'd be good to have an oceanographer's opinion on this.

Re:Solar????

[NeMon'ess]

As opposed to blanketing homes with solar panels. One way or another, energy is being diverted from the land or water. Considering all the energy being released from burning coal, oil, and natural gas, I'm quite sure solar technology will be a relative drop in the bucket for decades to come.

And now for some math...

[Anonymous Coward]

The US generates and uses about 3800 billion kwh of electricity per year.

ASSUMING this thing can convert a 40 degree F (22 C) temperature gradient into electricity at 100% efficiency (which it can't, just looking for order of magnitude kind of thing here) then a 6ft (2m) diameter pipe sucking water in at a 20fps (6m/s) velocity will suck up enough water to generate 1500MW.

Ignoring peak demand and all that, it would take 300 (300) of them to power the entire US.

Assuming an average ocean depth of 1000ft (300m

Re:IANAO

[14erCleaner]

If the energy they're taking is but a tiny, tiny fraction of the thermal energy availible in the ocean (which i think is most likely the case) then it won't be an issue.

The article says that the current world consumption of energy is about 1/300th of the energy available from the oceans in this way. I'm not sure if that's a tiny fraction or not, actually. Local effects on the ecology could be significant for a large power generation facility.

But the article also says that they can produce fresh water as a by-product, and that the process works best in the tropics (i.e. the developing world), so this might have a chance, since it'd probably be better for the environment than more fossil fuel consumption.

Re:IANAO

[MindStalker]

They said available in the equatorial zone. Actually these could be benificial in reducing hurricanes. You could also take this in the same manor as wind power, if you covered the earth in wind power generation facilities it would seriously screw up our weather, but a small single facility will do little.

Re:IANAO

[alw53]

Maybe cooling off the surface water will compensate for global warming and reduce the number of hurricanes :)

Re:IANAO

[rocket jockey]

global warmng isn't really an issue. Truth be told we don't know what the hell is happening to the enviorment.

Re:IANAO

[Kadin2048]

Er, no. I challenge you to go somewhere up north, where there has been visible increases in the rate of ice shelf retreat and glacial calving, and say that global warming isn't really an issue. The world is getting warmer, period.

The question that I think you're alluding to, by "we don't know what the hell is happening to the environment" is that there's still a (somewhat) open debate as to whether the warming is caused by anything human beings did, or if it's part of some greater and not-yet-understood cli

Re:Solar????

[networkBoy]

In fact I think there are three sources of energy on earth:
Solar
Nuclear
Stored friction (hot core)
everything is a stored form of something else, and the three above are a stored form of the big bang.
-nB

Re:Solar????

[JesseL]

Nuclear power doesn't derive its energy from the sun.

No, but it does derive it's power from heavy elements that were created by the explosions of older stars.

Re:Solar????

[sploxx]

        Nuclear power doesn't derive its energy from the sun.

No, but it does derive it's power from heavy elements that were created by the explosions of older stars.

And so does geothermal energy, which is feasible because of decaying radioactive elements (K-40 etc.) in the earth's interior.

Re:Solar????

[Boronx]

From another sun, as I understand it.

Re:Solar????

[msaulters]

Aha! But solar power derives its energy from the nucleus.

Think about it.

Re:Solar????

[khellendros1984]

Nucular. It's pronounced nucular. ;-)

Nuclear = Geothermal = Stellar Power

[Roger W Moore]

Actually depending on how strict your definition of solar is current nuclear power could be considered as such. If you allow solar to mean "from a star" and not just "sol" (which is not unreasonable since we talk of "solar systems" around other stars now) then fission reactors are actually using "fossilized" solar powered.

Fission reactors, our only current form of nuclear power, split uranium nuclei into smaller fragments and thereby release energy. However, to form the uranium atom in the first place from smaller constituents therefore required energy. This energy is thought to have come from a supernova ~6 billion years ago, predating the formation of the solar system. Thus current reactors are, by some (possibly warped!) definition, still using fossilized "solar" power. The same can also be said of geothermal which relies mainly on natural decay of nuclei formed by the same supernova.

Only if we ever get fusion reactors working then we really say that we are no longer reliant on solar based power...and that's because we will have made our own mini-sun.

Re:Solar????

[Jackazz]

Tidal energy is based on the motion of the moon, not the sun or its rays.

Re:Solar????

[Clueless Moron]

No, the energy is being taken from the rotation of the Earth. In other words, the earth day is slowly getting longer.

Also, the tidal force actually also gives energy to the moon, so its orbit is slowly getting bigger. Only a few cm per year, but there it is.

Unfortunately, it's not a passive energy source

[csoto]

Just like hydro power, this one has the problem of disrupting the environment, albeit a very local environment. By moving water against the normal gradient, you will warm up water that's supposed to be cold, and cool off water that's supposed to be warm. I could imagine plankton blooms and oxygen depletion, among other side effects.

Passive solar collection (photovoltaic and otherwise) and wind power are really the only truly "green" power sources.

Re:Unfortunately, it's not a passive energy source

[Elwood P Dowd]

Somebody please think of the bird decapitations.

Local?

[MAXOMENOS]

If this technology gets adopted widely enough, I doubt the problems will be local for long.

The parent is right on. This is just trading one environmental stressor for another.

Re:Unfortunately, it's not a passive energy source

[Deep Fried Geekboy]

Bullshit. They both redistribute exactly the same amount of energy as this does, just in different ways. There's no way to remove energy from any part of the ecosphere without having a local effect. The only question is whether the local effect matters or not. And by 'matters' I mean matters, not 'matters to the Green Taliban'.

Re:Unfortunately, it's not a passive energy source

[paco3791]

The problem with any power generation scheme is that there are always side effects, you just have to pick your poison.

With photovoltaic systems you have the nasty chemicals currently associated with manufacture, with wind power you have what some people consider noise and landscape pollution, along with bird strike problems, although this problem is probably over hyped with newer windmill designs.

There is, as they say, no free lunch.

Re:Unfortunately, it's not a passive energy source

[Rutulian]

I think really what we need to do is spread out the burden. All power generating facilities are going to cause environmental damage, but they are going to do it in different ways. Small perturbations aren't going to be as bad as large perturbations. So a few wind turbines will cause some noise pollution, but if you stick them out in the middle of Oklahoma and use them for that local area, it won't be such a big problem. You can setup a few solar plants, nuclear plants, coal plants, geothermal/aquathermal sy

Non-Photovoltaic Solar

[Ironsides]

There is a version of solar that does not use photo voltaic cells. Remember the Sim City 2K solar power plant? It looks a lot like that. An array of mirrors reflects light into a dome atop a tower. The dome contains a circulating supply of water that is heated up into steam and used to drive a turbine. The mirrors are automatically angled to reflect the sun (at pretty much any angle) into the dome.

No really nasty chemicals involved, and it uses technology that has been available for a really long tim

Re:Unfortunately, it's not a passive energy source

[lilmouse]

True. What we need is something like Trantor [wikipedia.org] - use the (negative) heat gradient from deep in the earth instead of the gradient in the oceans. Of course, we'll have to do more research drilling, but we're already getting close [msn.com] to the mantle!

--LWM

ps - no "think of the earthworms", please.

Re:Unfortunately, it's not a passive energy source

[bunnyman]

Won't somebody please think of the Balrogs!

Re:Unfortunately, it's not a passive energy source

[lilmouse]

Won't somebody please think of the Balrogs!

You bastard.

--LWM :-D

Re:Unfortunately, it's not a passive energy source

[pete-classic]

Wind turbines must slow down the wind. PVs must collect energy that would otherwise impact the environment.

Thermodynamics won't let you continuously pull energy out of a closed system.

Also, human beings are part of nature.

I'm glad we could have this little chat.

-Peter

Re:Unfortunately, it's not a passive energy source

[Fjan11]

Bt the same line of reasoning wind power would not be passive energy because wind mills slow down the wind. In reality the order of magnitudes are such that slowing down the wind, or changing the temperature of the ocean, is not a problem.

Re:Unfortunately, it's not a passive energy source

[Chandon Seldon]

Absolutely any technique to generate power will have environmental consequences. Wind power takes wind energy out of the atmosphere, which could cause climate change if used on a large scale. This proposal is about the same.

A very important point to remember is that we will use an increasing amount of energy for the forseable future and that energy will be generated somehow. Coal is the default power technology. Every time a wind / nuclear / tidal / etc power plant doesn't get built another coal plant is built instead. So the question isn't "Is there an environmental impact from this power source?" - we know that answer, there always is - the question is "Is this better than coal?".

Re:Unfortunately, it's not a passive energy source

[caseih]

No, even photovoltaic solar panels aren't passive. They prevent energy that would reaching the ground from doing so, altering the energy balance there. In short there is no form of energy that we can extract from nature that doesn't alter in some way (large or small) the natural energy flows and balance in nature.

Re:Unfortunately, it's not a passive energy source

[caseih]

Yup that would alter the environment too. In this case you're adding massive amounts of the energy to the Earth's natural systems from an outside source that wouldn't have been inserted into the system normally (ie you're taking energy that wouldn't have hit the earth and transferring it there). Although you may be thinking that this is pure electrical energy and has nothing to do with the environment, energy cannot be destroyed or created but only transferred. This electrical energy is disappated into t

Re:Unfortunately, it's not a passive energy source

[rob_squared]

Aside from valid ecological concerns, there are also mechanical concerns.

Salt water and weather in general will do a number on these devices. Waves cause variable pressure on this device and salt water is very corrosive.

Still, its a better choice than tide differential generators, which would die much faster due to moving parts.

Re:Unfortunately, it's not a passive energy source

[winkydink]

Passive solar collection (photovoltaic and otherwise) and wind power are really the only truly "green" power sources.

The processes to manufacture these are also green? Ever seen a semiconductor fab? Clean? Yes. Green? I dunno, what color is arsine gas? If you smell garlic, it ain't the pizza joint next door.

Re:Unfortunately, it's not a passive energy source

[alw53]

Big wind power turbines farms reduce wind velocities which will tend to increase air temperature gradients, making cold places colder and hot places hotter.

Re:Unfortunately, it's not a passive energy source

[Some Random Username]

First of all, the turbines killing birds myth is getting really tired. Buildings kill birds too, but we seem to be building those. Properly located wind farms do not kill significant numbers of birds. This myth comes from the fact that one particular wind farm was placed directly in a valley that birds migrated through, giving them no choice but to go through and risk being killed. There's tons of other wind farm installations which show birds who have a choice to go around them, do go around them.

And what do you think that solar energy is going to do if you don't turn it into electicity? The sun already raises the temperature last I checked.

Re:Unfortunately, it's not a passive energy source

[forand]

The sun doesn't raise the average temperature systematically, otherwise we would all be dead. The ammount of energy that the Earth gets from the Sun is, over time, exactly the same as it puts out. This fluctuates with the ammount of green house gasses in the atmosphere, but in general the Earth re-radiates the energy it gets from the Sun.

That said if we convert the energy into electricity then use it to power our lights and stuff it will get back into the atmosphere and get radiated away. So the energy is there for the taking.

Re:Unfortunately, it's not a passive energy source

[NeutronCowboy]

And what do you think that solar energy is going to do if you don't turn it into electicity? The sun already raises the temperature last I checked.

Right - and a good chunk of the world's ecosystems rely on this to continue. Remove the sunlight, transfer the energy somewhere else, and you've just removed local heat. Good? Bad? Who knows, as it largely depends on the circumstances. But it is something to consider.

Humph

[Descalzo]

"First of all, the turbines killing birds myth is getting really tired."

Tired myths have held sway over human thinking since time out of mind.

Re:Unfortunately, it's not a passive energy source

[snStarter]

Anyone involved with the raptors around the Altimont Pass would KNOW that wind turbines there DO kill substantial numbers of raptors including golden eagles and a wide variety of hawks.

This is NOT a myth.

Evolution in action

[Macka]

In this case its survival of the smartest. Maybe the birds around the Altimont Pass are particularly stupid and are doing the rest a favour by removing themselves from the gene pool. If I look at my front window, a quarter mile away is one of the biggest wind turbines I've ever seen. Can't say I've spotted a single bird carcass lying on the ground underneath it.

Personally I don't believe wind turbines kill birds. I call bullshit. The blades just don't turn fast enough. And anyway, birds very quickly get out of the way of fast moving objects. When was the last time you ran over a bird in the road with your car? Drive at 'em as fast as you like. They see you coming and by the time you get there, they've moved.

No, anyone involved would know the truth.

[Some Random Username]

"Research by raptor experts for the California Energy Commission (CEC) indicates that each year, Altamont Pass wind turbines kill an estimated 881 to 1,300 birds of prey"

That is not a large number at all, cars, buildings, pets, power lines, etc, etc kill WAY more than that. And the altamont pass is the single worst wind farm in north america for bird of prey deaths, because they were stupid and built it not only in the middle of a migratory path, but in the middle of the highest concentration of breeding golden eagles anywhere in the world, and with the blades positioned right at the typical altitude of those birds flight paths. This is exactly what caused the myth; old, improperly planned wind farms that haven't been fixed. Learn to find facts instead of just repeating nonsense you heard from whackjobs.

The fact that you think the tiny number of bird deaths produced by the worst wind farm on the continent is "substantial numbers" is just silly. And the fact that you pretend its indicative of modern, properly planned and constructed wind farms is just plain stupid. You can't say wind farms in general kill substantial numbers of birds just because a couple of bad wind farms were built.

The quote is from this page, there's more info there about what can be done to improve altamont specifically:
http://www.biologicaldiversity.org/swcbd/programs/ bdes/altamont/altamont.html [biologicaldiversity.org]

Re:Unfortunately, it's not a passive energy source

[Lifewish]

The point of solar power is that, rather than being converted directly to heat when it hits the ground, sunlight can instead be converted to electrical potentials. So no, it does exactly the opposite of what you say.

Re:Unfortunately, it's not a passive energy source

[Tyger]

Large scale solor generation usually focuses sunlight onto a tower where steam is generated to drive turbines.

And do you think photovoltaic solar cells are 100% effective in converting sunlight to electricity? Typically they are around 12% effective in converting sunlight to electricity. That means the remaining 78% is either converted to heat or reflected. If the alternative to the solar cells is something that reflects a good amount of sunlight, then the solar cells will be hotter.

Re:Unfortunately, it's not a passive energy source

[Tyger]

Okay I will eat some of my words on this one. I did a little more reading and apparently photovoltaic cells are designed to reflect light they don't use, though I found no reference as to exactly how much they reflect.

Commercial power generation tends to use the heat from the sun rather than the light directly, so my point still stands there.

Re:Unfortunately, it's not a passive energy source

[dbIII]

and solar power collection generates heat which could rais the local temperature

Then don't touch the glass!

As for this disrupting the temperature consider that this water system is both not a static situation (the warmed cold water will move away and will not pool there and get hot) and that we are also talking about very small changes to large systems. Still water with layers at different temperatures could set up currents when you break through layers just like what happens with air (eg. a plane arrivin

Re:

[account_deleted]

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Re:Unfortunately, it's not a passive energy source

[soupdevil]

Most solar cells I've seen are on rooftops and other places that don't take up any additional real estate.

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[account_deleted]

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Re:Are there environmental effects to be considere

[TubeSteak]

Weren't they recently worried about the ocean currents that carry warm water to Europe essentially turning off?

Maybe a bunch of these stations strategically placed would keep our various underwater thermal currents moving along.

As for ship vs oil rig, my understanding was that oil rigs were moored to the seabed, compared to a ship being anchored. I'm not sure how feasible it'd be to moore an oil rig in ultra-deep waters.

Re:Are there environmental effects to be considere

[Boronx]

What will the do when a giant squid inevitably crawls up the pipe and gets stuck.

No, the ocean is too massive

[jgardn]

The ocean is so grossly unimaginably big that we would need an absolutely huge operation to even cause a measurable effect. If you really tried to change the temperature by even a fraction of a degree using this method you would have to pump extremely large quantities of water---quantities so large that I don't think anyone would ever consider building something so massive.

People sometimes forget the scale of things. On a global scale, we are not even part of the equation.

But you also have to consider the o

Re:Are there environmental effects to be considere

[JesseL]

I'm not going to be too happy exchanging a few KW of electricity for another ice age.

Don't worry. Global warming will make it all balance out.

Re:Are there environmental effects to be considere

[squidfood]

I'm sure someone can go into the math of exactly how much energy the ocean contains by multiplying water's heat capacity to the amount of water in the oean, but I'm too lazy to do that.

Gosh, I am disappointed in the quality of nerds these days. Ever heard of the back of an envelope? For god's sake, units of energy are defined by how much they heat water, so it's not hard to figure this one out.

Projection from http://www.eia.doe.gov/oiaf/ieo/world.html [doe.gov] is that the world will use 645 quadrillion BTUs of energy per year in 2025. If we assume this all comes from the ocean at 100% efficiency, this would be enough to raise a patch of water, 100m deep by 1024km on a side, by 1 degree C. Insignificant next to the whole ocean? sure. But certainly significant compared to local or even regional climate variation! (not that hydrocarbons aren't worse, or that this can't be spread out but hey, now all the slashdot blather can be vaguely informed. sheesh).

Sticker: Linux Inside.

[Anonymous Coward]

"SSP should be ready to build their first full prototype 2-3 years from now.""

It will run Linux (everything else will by 2007-2008)

This isn't news

[remy]

I did a report on OTEC when I was in junior high--18 years ago--based on an article in Scientific American. There are prototype facilities in a number of countries--I visited the facility in Hawaii five years ago, which was at least a decade old then.

It's an intriguing idea, but this smacks of somebody trying to get publicity to bring in venture capital or something of the sort.

Re:This isn't news

[JesseL]

Agreed. I read an article about this when I was digging through a box of Popular Science magazines from about 1972.

waves?

[User 956]

why not just harness the wave energy [freeenergynews.com]?

Re:waves?

[Mozk]

I keep reading harness as harass for some odd reason.

"Harassing Vertical Sea Temperature Gradient"
"Why not just harness the wave enery?"

Yeah check out those nice smooth bumps! It sure does make me wet...

Re:waves?

[jgardn]

Because dolphins happen to live closer to the surface of the ocean than the bottom, along with the vast majority of sea life. And waves are plentiful near the shore, where they would be seen by people and interfere with ocean traffic.

This could be built out of sight and away from the vast majority of living sea creatures. You have to build it where the ocean is very deep, namely, away from where most people live.

Re:waves?

[lilmouse]

Waves depend on things like wind and tides to work. Winds change with the weather, and tides change all the time (at least tides are regular). Whereas it's *always* possible to get a 20degree heat gradient.

Besides, if you put your heatsinks below the surface of the water, you don't have to worry so much about storms and such.

--LWM

SMAC's Realization

[Erioll]

Nice to see concepts popularized (though hardly invented) by Sid Meier's Alpha Centauri being realized, considering this is basically like a Thermocline Transducer.

Choice of phrase

[jtorkbob]

'Has developed'? How about 'is developing'?

I mean, in the last year, I've read about thermal stacks, hydrogen generation using thermal power, horizontally-oriented wind turbines, and probably some other alternative power methods. They're all great ideas, with great possibility, but the summary for every one reads like a sales pitch.

Hurricane Control

[truckaxle]

Set up shop in Caribbean or Gulf of Mexico and maybe as a added benefit, such energy harvesting, could decreasing hurricane potential by cooling surface water temperature. This would be win-win, but I am sure that it would also be disruptive to some marine life so maybe a win-win-lose sometime you just can't have it all.

Re:Hurricane Control

[lcsjk]

How about a huge windmill farm in the hurricane's path coupled to a huge battery bank and/or capacitors. Then we can harness enough energy in a day or two to last for a year.
Another alternate to that is to build a windmill farm just offshore that pumps water like crazy out of Lake Ponchatrain when hurricane force winds arrive.

Boy, I'm full of it today. Somebody send me home. (It's not spelled right, but I don't care.)

Re:Will Hurricane Control be win-win?

[truckaxle]

Or maybe we could just shape Hurricane tajectories so that they hit cancun instead of new orleans :)

Reverse Refrigeration

[Fitzghon]

"...using a reverse refrigeration cycle."

We have a name for those. They're called engines.

Fitzghon

Re:Reverse Refrigeration

[nsayer]

We have a name for those. They're called engines.

Indeed [wikipedia.org].

Old News

[Belseth]

I've been reading about this since the 70s. It's a great idea and I can't understand why no one has built a prototype yet. Most of the systems I read about proposed using something like amonia since it was dealing with a temperature difference rather than high temperatures. Some chemicals like amonia boil at very low temperatures. They don't produce the power steam does but it's a stable source. Deep ocean temperatures are near freezing where as surface temperatures can be 40 to 50 degrees higher in the same area. Some have complained about cooling surface water. The ocean is a mighty big heat sink and it's doubtful plants that are spread out would have much affect. In truth it might help offset some of the surface warming caused by global warming. I'm not sure enough plants could be built that would drop ocean surface temperature one degree. Temperatures have already raised that much in the last 100 years.

Re:Old News

[alienw]

There are a few prototypes. Search for OTEC on google. The problem is, there isn't enough of a temperature difference to efficiently extract any useful energy. You basically have to pump HUGE quantities of water (like a 10m diameter pipe) to the surface and have enormous heat exchangers and stuff that extract the energy. You use a lot of energy to pump the water and it requires enormous capital investment for very small amounts of energy.

Environmental damage?

[eagl]

Won't this mess up the natural mixing currents that already go on? The global warming crowd is convinced that the ocean's natural mixing patterns are being disrupted and this will cause unpredictable climate changes and they have some data to back up their statements that a previously stable system is being disrupted, but now people are talking about deliberate disruption of the temperature gradiants and thermocline?

It really does not sound responsible to me. We're already tampering with the climate and s

awesome but...

[MoFoQ]

why can't they use a heat-exchanger with conjunction to the one-way thermal transfer materials (I think a product of nano-technology) that was being tested and was slashdotted last year so they don't have to worry about any marine growth growing or dying in the plant itself?

And why not also use the energy to produce methanol or methane using the freshwater and probably carbon dioxide from the air or from industrial waste from the mainland? Heck, even ethanol so it can be used in cars to help reduce relianc

Re:awesome but...

[MoFoQ]

ssshhh....u might be bugged....(Bush Administration's Decision explains alot)

In this house we pay attention to carnot

[truckaxle]

The problem here is the huge quantity of thermal energy that needs to be exchanged for a small amount of useful work. To generate work between a 80 degree f source and a 50 degree f sink the best you can do is around 7 percent efficiency.

Seven percent of what?

[localroger]

The amount of energy in the ocean is huge. Really huge. Hurricanes are a really small expression of that, and hurricanes make thermonuclear weapons look like kiddie toys.

Multiply a kilowatt or so per square meter insolation by the size of the ocean, take seven percent of that, and get back to me on whether you think it's enough.

Re:Seven percent of what?

[dsci]

Multiply a kilowatt or so per square meter insolation by the size of the ocean, take seven percent of that, and get back to me on whether you think it's enough.

So, you're basically going to build this to cover the entire ocean? Either that or you've got a heck of an equilibrium problem, there.

Re:In this house we pay attention to carnot

[dbIII]

The problem here is the huge quantity of thermal energy that needs to be exchanged for a small amount of useful work

That's why we currently burn a lot of stuff to make steam. However with this ocean idea you have little in the way of running costs and very simple technology for a base load station so that offsets the low output. Sticking it out in the sea with wires attaching it to land makes things more complicated.

Well over a hundred years ago the first electrical power generated in my state used the

Changes on natural cycle

[hoka_hey]

Deja vu!?!

There is a global circulation system called thermohaline [wikipedia.org]. Basically in three relative small areas of the oceans the water sinks until the bottom, and then spread around the world. This water slowly go up again and the system is closed with surface warmer waters flowing in direction of the areas of generation.

I'm not even considering the energetic balance of the proposed structure, but if it works it might reduce the vertical thermal gradient and make the thermohaline circulation weaker. Maybe stop it. The movie "The Day After Tomorrow" is a fantasy about it, but be sure at least that the surface temperature on the North Atlantic would reduce since is one of those areas of generation of deep waters. You can imagine how would be the winter on Europe and North America? Would need a lot of energy to keep people warm there!

Wikipedia entry

[amembleton]

Wikipedia entry on the subject of Ocean thermal energy conversion: http://en.wikipedia.org/wiki/OTEC [wikipedia.org]

How can I take seriously ...

[Culture]

... any information from a web site that calls stochimetric mixtures of oxygen and hydrogen "Brown's Gas" and claims that it "takes on the properties of what it is exposed to -- not in a physical reproduction, but in essence." Or try this gem: "When the electricity (in the Brown's Gas) is released by the 'flame,' it comes out as electricity and the water 'implodes' to it's original liquid form, with no heat and no expansion first. That's also why the flame is 'cool' yet has high energy effects." Yeah ... right. Take a look at the "Gravity Motors" section. It is even funnier.

I guess I am being punished by my mechanical engineering background.

It is possible that there is some good information on this site (somewhere), but quite frankly I do not know what you would want to waste time separating the real information from the quackery.

Some info for the perplexed

[dsci]

About Brown's Gas:

Brown's Gas Information [phact.org] and Eagle Research [eagle-research.com]

As for "When the electricity (in the Brown's Gas) is released by the 'flame,' it comes out as electricity and the water 'implodes' to it's original liquid form, with no heat and no expansion first."

As you said, pure rubbish. It does explode first to produce water vapor, and the condensation of water vapor to liquid water does liberate large quantity of heat.

Interesting Tech, but Geographically Limited

[lorelorn]

The technology they are using is interesting, and they have pilot systems up and running, which are working fine in pacific island environments for 'low level' power needs. This is good, as pacific islands typically have to import fuel to burn for their power, and this technology does away with or at least reduces that need/

The only thing is that you need easy access to deep ocean close to land in order for this to work. In other words you need a 2000m (or deeper) ocean trench a short easy distance from th

Under Salt Water

[Heembo]

Under-ocean electric generation methods are doomed to be radically costly to maintain. Damn, ever see what salt water does to most machines over time? Not pretty.

go nuclear

[circletimessquare]

pebble bed reactors don't go china syndrome. environmentalists attitudes about nuclear is based on decades-old technology and watching too much "silkwood"

thermocline, solar, biodiesel, wind, tidal turbine, wave generated, etc.: these are all very cute boutique energy sources. but when all put together and maxed out in terms of realization of potential they won't dent 5% of our energy needs

oil and gas and coal are incredibly dirty and even geopolitically dangerous and increasingly expensive

put it all together and pebble bed reactors are an environmentalist's and energy policy maker's best friend

now we just need the lowest common denominator of uneducated environmentalist's opinions to catch up with reality

ps: YOU CAN'T MAKE BOMBS OUT OF IT

educate yourself, don't let your uneducated fears dictate your opinion

as time goes by, nuclear is only going to look more and more attractive to this world, once everyone gets a real education of the positves and negatives of nuclear compared to everything else

because the biggest thing going against nuclear really is only inertia and ignorance

Duplicate and again

[JackL]

Looks like we have covered this topic rather [slashdot.org] well [slashdot.org].

The discussions were better on those, too.

Jack

Sounds like a hoax

[Yartrebo]

I really, really doubt that this thing is practical. Organic Rankine Cycle Turbines (which are proposed) are very expensive to operate on dry land, as has been shown by research into solar thermal power in California. At least in those cases the efficiency was around 20%. The best they can hope for with OTEC is about 1.5% efficiency. Theoretically they could get 3.25% (Carnot efficiency), but experience with Organic Rankine Cycle Turbines has shown that 300C solar plants (Carnot Efficiency ~50%) only get around 20%, so one could expect to get about 1.25% efficiency out of their OTEC setup.

On top of this, all the equipment must be marine grade (ie., pricey). Power must be transferred to shore. It also must be a functioning ship with all the expense associated with that.

But what makes me most suspect is the claim of making fresh water. Ordinary Rankine Cycle Turbines do produce fresh water via distillation, but the Organic Rankine Cycle is a closed cycle and no fresh water is produced. The only condensation you'll get are hydrocarbons, which are recycled to create more vapour.

Isn't it 4 degrees all the way down?

[GrahamCox]

Correct me if I've got my wires crossed, but I thought the sea temperature was about a constant 4 degrees all the way down, once you get below a certain distance of the surface. The reason being, that water colder than 4 degrees has lower density, therefore always floats upwards. That's why the ocean isn't frozen at great depths. It doesn't mean you couldn't tap that gradient anyway, but the depth required presumably wouldn't be all that much as long as you'd got at least as far as the 4 degree level.

Ah. Yes.

[Amiasian]

Yet again, I am reminded of Marshall Savages thought-provoking work, Colonizing the Galaxy in Eight Easy Steps [google.com]. His belief is that the use of OTECs will relieve the world's energy problems, in addition to providing power for floating sea colonies, thus relieving population density. Furthering his premise, if I recall, the warm water will lead to an abundance of blue-green algae, which can be processed and used as a food source. These things, interestingly enough, are only a stop-gap until we can begin to expand life to places outside of this current biosphere.

Okay, maybe a tad off-topic, but I certainly find it fascinating.

Re:Sound too good to be true? Perhaps it is...

[bcrowell]

With this in mind, is it really wise to start monkeying with the thermal gradient of the oceans at the equator?
Do the math. The entire world's energy budget isn't enough to make even a microscopic change in the thermal gradients of the ocean.

desalination: yeah right!

[nietsch]

from their own site: A vacuum is pulled on the incoming warm water to remove the oxygen so as to prevent marine growth on the inside of the plant. call me a dumb biologist, but is there enough energy stored in the 40 degrees F difference between the warm and cold seawater to pull this vacuum and remove a significant amount of dissolved oxygen/nitrogen? I do have my doubts on that.
Combine that with the fact the technique takes a very long time to move into production and is still 2-3 years away from actual

at what efficiency?

[pin_gween]

I am all for greener technologies but, at what cost does this come? While OTEC seems like a great investment, what is the efficiency of this?

If you have too high an input energy pumping the water from such great depths, you lose efficiency. Where is the energy for the pump going to come from?

I won't get into efficiencies of other methods, I know most sources are horrendous too. This technology is probably too self limiting to become widespread.

Re:Sound too good to be true? Perhaps it is...

[ltbarcly]

Abundant power plus abundant fresh water has the potential to completely remake the countries in the equatorial region...

For 20 years. Then the population will have had time to exceed the newly available resources, and they'll be in the same condition they are now, except there will be 5x more of them. The third world doesn't need energy, medicine, water, or food. Not the long run, as no matter how great the supply much of it will be stolen or ruined, and the population will just grow to exceed the suppl

Re:Sound too good to be true? Perhaps it is...

[electroniceric]

I'd hardly call this "debunking". I happen to know David Battisti, and I think he's a good and credible atmospheric circulation researcher. On the other hand, plenty of other good and credible oceanographic circulation researchers I know would refute this, and have done extensive work on the amount of heat transported by the Gulf Stream, and its role in sustaining thermohaline circulation and associated climate effects. A press release about paper maketh noth scientific truth.

Not only that, but even if the Gulf Stream is not the primary deliverer of heat to northern Europe, the 20-line press release you cited does not claim that Europe's climate will not be affected by a change in thermohaline circulation.

So if you're searching for a thin vine to cling to the increasingly untenable view that carbon-loading of the atmosphere is not a major problem, better not grab too hard on this one.

Re:Under the Sea

[ObsessiveMathsFreak]

What more is you lookin' for?

Cheap fuel.... and lower taxes!

Re:environmental impact?

[dbIII]

There is no mention of obvious environmental impact. Obviously, warming the ocean floor on large scale will disturb the ecosystem balance.

Consider holding a candle under a water pipe with flowing water as distinct to a small pot of water. It isn't a static system, there is a lot of cold water moving about so the heating is spread about a great deal - plus hot water rises. If a huge installation is put in a small deep lake things may happen, but otherwise you need to consider the scale of things and how ma

Re:Lets get on with replacing coal

[be-fan]

The problem is that each of these technologies has a prolem. Nuclear power scares midwesterners who are worried that we'll start using their back yard as a waste dumping facility. Wind power worries those who love the little birdies. Hydro power screws anybody down-stream of a hydro station, who previously depended on the free-flowing river that is now dammed up. Aquathermal (OTEC), scares the "chaos theory" butterfly flaps its wings contingent. Apparently, all the various brands of tree-huggers consider oi

Re:Are They Kidding?

[dbIII]

Okay, let's just pretend for a second that all of the "science" in this plan is on the up-and-up and that

It's very simple thermodynamics for the basic idea - doing it cheaply is the hard bit, which I suppose is why they are using sea water and not something obvious like ammonia for the working fluid - which would be a 100+ year old method really (refridgeration cycle).

If some random French guy nobody's ever heard of had it figured out 120 years ago

Over a hundred years ago this sort of method of using hot

Re:Dang laws of physics get in the way again!

[ltbarcly]

The energy needed to lift heavy things (like water) is greater than the energy in the temperature difference.

If you believe this then your entire post is suspect.

This process won't have to 'lift' any water. Since they are moving the water up in a tube which is surrounded by water, they are really just circulating water around, which requires very little energy. By your logic it would be impossible to coast on a bike, since you have to continually lift the part of the tire touching the ground all the way u