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 (724999)]

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

Re:Solar????

[MarkPNeyer (729607)]

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

Re:Solar????

[Lifewish (724999)]

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:IANAO

[14erCleaner (745600)]

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:Solar????

[networkBoy (774728)]

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 (107722)]

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????

[msaulters (130992)]

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

Think about it.

Re:Solar????

[khellendros1984 (792761)]

Nucular. It's pronounced nucular. ;-)

Nuclear = Geothermal = Stellar Power

[Roger W Moore (538166)]

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 (572024)]

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

Re:Solar????

[Clueless Moron (548336)]

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 (220540)]

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 (16933)]

Somebody please think of the bird decapitations.

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

[paco3791 (786431)]

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

[lilmouse (310335)]

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 (121652)]

Won't somebody please think of the Balrogs!

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

[lilmouse (310335)]

Won't somebody please think of the Balrogs!

You bastard.

--LWM :-D

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

[pete-classic (75983)]

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

[Chandon Seldon (43083)]

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 (160668)]

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

[winkydink (650484)]

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

[Some Random Username (873177)]

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 (530402)]

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 (896098)]

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.

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

[snStarter (212765)]

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 (9388)]

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 (873177)]

"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]

Are there environmental effects to be considered?

[mmell (832646)]

For example, they're talking about exchanging a thundering lot of heat here. Will this affect existing ocean currents? Might the thermal change not impact on the underwater ecosystem (a system we are only now beginning to even be able to see)?

Further, what of the potential for secondary effects? Climate changes brought about by changes in ocean current temperatures? Remember, el nino/la nina are caused by a change of only a few degrees. That's not unforseeable for a large-scale technology such as this.

Oh, and BTW - it makes a lot more sense to base this on something like an oil rig, rather than a ship. Just sayin', is all.

No, the ocean is too massive

[jgardn (539054)]

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 (107722)]

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 (149212)]

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.

[by 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 (82535)]

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.

waves?

[User 956 (568564)]

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

Re:waves?

[lilmouse (310335)]

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 (229536)]

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 (885054)]

'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 (883149)]

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.

Old News

[Belseth (835595)]

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 (585907)]

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.

In this house we pay attention to carnot

[truckaxle (883149)]

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.

Changes on natural cycle

[hoka_hey (837488)]

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 (411990)]

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

How can I take seriously ...

[Culture (575650)]

... 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.

Under Salt Water

[Heembo (916647)]

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 (444983)]

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

Sounds like a hoax

[Yartrebo (690383)]

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 (741991)]

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.

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

[bcrowell (177657)]

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.

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

[electroniceric (468976)]

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.