Slashdot Mirror
New Power Plant Produces Both Energy & Fresh Water
joshmccormack writes "An article in Sunday's New York Times (Free Reg, mah peeps) tells of how Japanese scientists have found a way to make fresh water and energy from temperature differences in ocean water. This may change the rules of what land is considered habitable, and the value of energy." Fascinating stuff, next step is rumored to be beer and power.
After reading the headline, the combination of these two things is like starting a company that sells fireworks and flamethrowers... but after reading the article it actually makes a good deal of sense.
sig.
FP? Anyway, I've visited that type of plant (OTEC, Ocean Thermal Energy Conversion) already in Hawaii (near Kona), where there is one running since quite some years. One problem is that it only works for steep ocean wall drop offs, since otherwise the pipe is getting too long.
It uses about half of the created energy (through a normal Carnot cycle) for pumping (about 120kW). The other half is not quite competetive, but with the nutrient rich and cool water, fish farming and air conditioning can be done, heaving the whole investment to a black zero (or better).
I leave the exercise of finding the link to a Karma-hungry reader.
Hurricane Application Group, Dept of Meteorology Control, Ministry of Proactive Defense
Temperature difference in sea.
the temperature difference is enough to liquify certain gasses, and then expand it again.
Just like the refrigerating unit.
Not to mention the increase of pressure water gets deeper.
Having lived on a island in the south pacific for a year I learned how important fresh water is. The aircraft landing strip that we had acted as a big water collector - water would drain into pipes and then was cleaned by a chlorination process. The idea they propose is a good one and would work in many islands out there - where they desperately need easy access to electricity and fresh water.
I am sure more will be available about the subject at a later date but, here is what would be interesting to know:
+ How much power/water does one of these amonia powered drinking fountains produce?
+ Is it scalable, should I start writing my congress person to de-comission Califoria's oil powered plants?
same story here
Before adopting WHATWG, read the moonlight.NET EULA [http://www.microsoft.com/interop/msnovellcollab/moonlight.mspx]
I heard that in some arabian countries beer is less expensive than water.. In near future this could also allow folks down in US to get their industrial energy(Oil) from somewhere else than Irak? ;)
Japanese Technology May Help Islands Reap Pacific's Waters
By AGENCE FRANCE-PRESSE
KYOTO, Japan, March 22 -- A number of Pacific island nations are discussing using new Japanese technology that can both desalinate seawater for drinking and produce electricity by exploiting the difference in temperatures between the surface of the sea and the depths of the ocean.
The Republic of Palau in the western Pacific is working with Saga University in southern Japan to build a system that can produce enough drinking water to meet the needs of its 20,000 residents, while producing electricity, said the country's president, Tommy Remengesau Jr.
The concept was highlighted this week at one of the 350 sessions at the Third World Water Forum, which is under way here. It has attracted 10,000 participants from around the world, along with ministers and some heads of state from more than 150 countries.
The university is preparing to build an experimental power plant off the coast of Palau that brings up cold seawater from the depths of the sea to an evaporator chamber near the ocean surface.
As the water is heated by the surrounding warm surface water, it releases ammonia gas, which then drives the system's power generator, said Yasuyuki Ikegami, deputy director of the Institute of Ocean Energy at Saga University.
Meanwhile, the heated water would be transferred to a separate low-pressure chamber where it boils at a lower temperature, producing steam, which would be condensed and collected as fresh water for human consumption, leaving salt crystals behind.
One experimental system, which produces power but no usable water, is scheduled to be put into use off the coast of India this month, Mr. Ikegami added.
"It works well especially in the western Pacific, where the temperature difference between the ocean's surface and deep seawater is" as much as 43 degrees Fahrenheit, he said. "It is environmentally sound."
With some financial assistance from the Japanese government, the university was hoping to build the experimental plant in Palau for $7.5 million, said Haruo Uehara, president of Saga University, although he declined to disclose details of the financing because it was still being negotiated.
Palau was hoping the plant could be built next year, Mr. Remengesau said.
"It is a big help for us," he said. "When there is rain, we have no problem. But we are hit by the drying effects of El Niño. When there is no rain, where can we get drinking water?"
The fresh water produced by the system will cost less than $1 for more than 250 gallons, Mr. Uehara said. "It is no more costly than regular tap water in other countries, including Japan," he said.
The system, while more expensive than ordinary generators, has raised hopes among leaders of other Pacific islands, which are too small to build many dams to catch water and are trying to cut back on their consumption of oil to run power generators.
Allan Marat, deputy prime minister of Papua New Guinea, said Pacific island nations had fallen victim to global warming, adding that he too was interested in the university's system.
"We are in the middle of the largest body of water" on earth, said Robert Woonton, prime minister of the Cook Islands. "Yet, we are faced with lack of safe potable water." He said he wanted to consider setting up Saga University's system in his country.
Other countries in arid zones have also shown interest, including Saudi Arabia, which was sending a delegation to the university, Mr. Uehara said.
Strictly speaking, complete combustion releases energy and water (and carbon dioxide), and combustion engines are power plants that have been producing energy and water for quite some time.
Of course the operative word there is complete and as we all know your typical combustion engine passes (at least) a few PPM of unburnt hydrocarbons along with the other combustion products.
There are no karma whores, only moderation johns
The article wasn't clear whether the ammonia is re-absorbed or released into the atmosphere. I'm guessing it would have to be released, otherwise it'd be some kind of perpetual energy system. Assuming that's true - surely this system is just the same as burning fossil fuels? except it's releasing nitrogen based nasties instead of carbon based ones. Or am I misguided again?
Bringing cold water from the depths has an unmentioned potential side-effect. Will it be replaced by warmer water from elsewhere? Cold, deep waters often support amazingly rich ecosystems. Raising the temperature even a few degrees could easily destroy entrie habitats. Will these generators warm the depths, and what effect will that have on the deep ecosystems?
Fresh water and clean energy? Sounds awfully unamerican and likely to support terrorism.
Considering that they have Beer Water (whatever that might be) in Japan, the rumor might hold some truth;)
This affects not only the athmosphere by releasing ammonia (which is only a minor problem), but also the temperature balance in the ocean. Things such as the major ocean currents are driven by differences in salinity and temperature of the water. The big currents control at least part of our climate - eg. if the Gulf Stream were to shut down (which some think it might all too easily do if the polar ice cap melts), we will probably have a new ice age
And before you start jeering and making stupid jokes about it, remember that only 30 years ago the idea that human pollution could affect our athmosphere and the seas, was regarded as utter nonsense and hysteria.
When I was about ten I read one of those cool-science-futures-for-kids magazines, which showed a floating OTEC with a vertical downpipe - that makes more sense, as it doesn't rely on rare coastal relief. I believe Bruce Sterling's novel Islands in the Net also had similar floating OTECs. Perhaps building such a device of the necessary scale (you have to pump a lot of water around, after all) just isn't economic?
Even if you do get mass OTEC production working, its quite debateable if it's really such a good idea. It's a lot of effort (money, materials, time) devoted to something that doesn't generate a terribly impressive amount of energy, and by its very nature it both warms the deep water and cools the surface water, which will have localised environmental consequences.
I despair that everyone is concentrating on renewable resources while so many people (particularly in hot western US states) live in essentially uninsulated houses with single glazed windows. Biomas, geothermal, wind, solar, and ocean generation are all expensive and uncertain - tripleglazed solarglass windows and super-thick wall insulation are available fairly cheaply right now, are guaranteed to pay for themselves way before a windmill, an OTEC, or even a biomass plant. Yet still we're paying to air condition the sky.
## W.Finlay McWalter ## http://www.mcwalter.org ##
The Moon's gravitational pull? The article isn't /.ed yet you know... ;-)
This system is driven by temperature differences, not tidal movements, meaning the ultimate power source is mostly the sun with some input from the earth's core. AFAIK we don't get much heat from the moon's gravity ... (Just as well, really: any energy we extracted from it would be orbital kinetic energy. Draining that is bad, since it would cause the orbit to decay and squish people.)
In the long term, I hope fusion will be successful; so far, the biggest research reactors only just pass the break-even point (generating more power than they consume), but the difficult bits (getting a reaction going, then feeding fuel in and removing waste while the reaction continues) are just about solved well enough to build bigger reactors. In the short term: fission. Wind and solar still can't produce enough power; oil - well, we know where that gets us! Gas is OK (and at least the US has ample domestic sources of natural gas, so no need to pour cash into Arab states which hate us...) but still produces pollution. Coal is the worst of all: not only does it pollute on a scale normally only seen in nightmares, it even produces more radiation than fission! (All carbon is slightly radioactive, which is how carbon-dating works; when you burn coal by the truckload, all the little bits add up to more than the small amount of uranium used in fission plants.)
So: Kill fossil fuelled powerplants, build more fission, and keep researching fusion. "Renewables" are improving, but still can't do the job properly - apart from anything else, solar and wind power don't even work 24x7, and power storage is nowhere near advanced enough to compensate. So, those nice clean "renewable" plants still need a conventional power station as backup!
It would be tempting to think of this as a "free" source of energy. We have to remember that we probably can't stick these plants everywhere because the oceans are the engine behind our weather.
OTECs Have great capabilities but have some limitations. The best way to get energy from thermal exchange is by having the greatest temp contrast. Equitorial waters are the most suited. OTEC that use an amonia to enhance the reaction do not leak it out. Basically deep cold water is mixed with warm surface water in a vaccum turning it to steam. The by-products are clean fresh water and hydrogen. Also the water brought up is heavily mineralized which has its uses in secreting a concrete like substance. Sea-Crete as some call it basically is same thing sea shells are. By using iron rebar for instance you immerse it in this heavily mineralized water and apply a slight electrical charge and you can grow this sea shell sea-crete stuff, its not fast but its strong and natural. Theres this group that has a idea of using a few OTECs and building a city near the equator on the ocean. The mineralized water is also usefull in mariculture, aka growing fish and crusteaceans. They plan to grow spirulina on the surface of the mariculture ponds. Spirulina is a plant/algae that when dried to powder is a potent source for nutrients. They think they can make a stable economy for this said city off exporting fresh water, sea foods, spirulina, and the hydrogen which the OTECs are central to producing all those including power in excess. And we all want clean power and hydrogen for those new fuel cell laptops coming next year. Course, if they built it exxon or someone the like would probably run into it and sink it. Or maybe a US submarine??? Though seriously, if the petro companies were real smart instead of fighting and stifling new energy theyd help develop it and get in at the ground floor of a new industry. Rant mode off...Those who use power without wisdom cannot claim courage...
I've seen a few posts here speculating that if ocean thermal energy conversion is scalable, we potentially have a miraculous supply of renewable energy. Sorry to pop bubbles, but OTEC is way too inefficient, expensive, and low-density to work on a larger scale. It's only viable for remote islands that need fresh water, in very warm areas, with a seawater temperature gradient of at least 20 degrees celsius. Otherwise, it's too expensive and inefficient to bother.
A theoretical 100MW plant (Current experimental sizes are lower than 1 MW) would require a hugely expensive floating platform, connected to the mainland by a hugely expensive submarine electric cable.
Because OTEC is a very low-density resource, a 100 MW plant would have to be massive... pumping, processing and discharging a volume of water equal to the flow of the Colorado River into the Pacific Ocean. On top of the massive construction costs, electricity generated would cost about $0.22/kW (as opposed to wholesale price of $0.02-$0.03.kW in the US). If just 1% of world energy consumption (60,000 MW) was met by OTEC, the cost of building the infrastructure would be $1,000,000,000,000 (one trillion dollars) and the discharge from the plants would exceed the combined discharge of every river one the planet into the oceans. Scalable? Maybe not.
Next to the sun and the wind, the Moon's gravitational pull on the earth is about the only other source of near infinite energy this planet has.
The Moon's gravitational pull on the earth is indeed a renewable energy source... but it's not a resource. A resource is something that is actually worth exploiting. Current experimental tidal power plants are extremely expensive, environmentally disastrous (they kill all the species that feed/lay eggs on the shoreline), and produce pathetically small amounts of energy. Google the Bay of Fundy experiment for more info.
Ocean thermal energy conversion isn't much better than tidal... too low-density and remote to ever be economical.
But you forgot the best renewable of all: GEOTHERMAL! It's good for at least a billion years and there's enough of it accessible within 3km of the earth's crust to power the whole world - ten thousand times over. We just have to wait until the technology catches up so that we can harness geothermal power effectively. When that happens, all this speculation of "wind" and "moon" energy will seem as silly and archaic as Wiccans exploring the healing powers of homeopathy.
Yes, but I think we all remember what happened last time the Japanes messed around with power plants. That's right: Godzilla. With Mothra defeated and major military forces otherwise occupied, the situation looks grim! Beware the denizens of the deep!
More studies are needed, but the real environmental problem with OTEC is not ammonia, nor is it the temperature balance of the ocean. Ammonia would only be released by accident, and even then it wouldn't be much of a problem.
Temperature balance is regulated because hot and cold streams of water leaving the OTEC are mixed, and then discharged by pumping it to a depth of about 60m, where the water temperature is about equal to the discharge temperature.
The real environmental issue is the fact that 99% of the seawater going through the plant is discharged back to the ocean (rather than being evaporated to fresh water). This means that huge volumes of water - thousands of gallons per second - most be pumped to generate a relatively small amount of electricity. The problem is that for every gallon of seawater that passes through, most of the plankton, algae and other tiny sea creatures who live in that gallon don't survive the amazing journey. A 10 MW island OTEC plant would inevitably destroy thousands of tons of biomass at the bottom rung of the local food chain.
Not like a fusion plant, that has all those problems radioactive waste is generating. (And the waste from fusion plants is not even useable for building ammunition like the uran is)
You are mistaking fusion with fission. Nuclear fission (breaking apart) is what we use now in the power plants. Nuclear fusion (coming together) is what we are experimenting with and are just getting to work for very short times in experiential reactors. Fusion takes 2 small atoms like H and He and forces them together. It does not use highly radioactive fuel (U-23x), nor does it produce waste with a 10,000 year half life.
Also, weapons can be made from the depleted U from fission plants. They put it in the tip of tank shells because we can't make it fly any faster so we make it heaver. (U is around 10% heaver than Pb). It will not work for a nuclear weapon, but it can be refined and converted into stuff the that can make one.
Go to the link -- it's good.
One interesting power / water / greenhouse idea I read in New Scientist a while back involoved building a big glass air hanger in a hot climate on a reliably windy spot near the coast - the windward wall was built as a metal framework filled with porous wate absorbant material (straw in the example) which had sea water running down it in a waterfall.
As the hot wind entered the hanger it evaporated a large amount of water, and cooled substantially. The climate within the hanger was therefore wet and cool and sunny - perfect growing conditions (and NOT saline!).
At the far end cool seawater was used to cool a big condenser to get fresh water out of the air leaving the hanger.
The water pumps were relatively slow operating, so could run on relatively crap solar panels.
This idea didn't so much generate energy as avoid the need for the stuff in the production of water - and it enabled the reliable growing of a wide range of crops in an otherwise arrid climate
Or is this how all OTEC plants work??
Any sufficiently advanced technology is indistinguishable from a rigged demo
--Andy Finkel (J. Klass?)
I think the DoE deep sixed research on this in the late 70's becasue these would have to be in international waters halfway around the world in order to be effieient.
-=fshalor
I keep seeing people that claim that fusion and fission are the way to go, still I have a question...
:-)
I am absolutly not knowledgeable on the subject so beg with me...
I was reading two link, this and thiswhich kind of explain all this to kindergarden level audience, read fine for me.
And from what I understood, fusion uses both deuterium and tritium at the moment. They state that both are a nuclei of hydrogen.
They go on to say that deuterium can be found in water while tritium can be found in the lithium in the earth crust
First of all, they say that they extract the deuterium from sea-water and lithium from the earth crust/sea water (one says earth crust the other says sea water).
While the amount of energy they can produce with this kind of reaction is very impressive, and the waste is supposed to be 100X less then with fission,
how will they manage to clean it up after 100 years? And how is it renewable energy?
I understand that it is VERY efficient, and I am all for that, just want to know how it is renewable.
And how do they clean up the resulting stuff? Maybe it is 100X less radioactive then the result of a
fission plant, but it is still radioactive none the less, isn't it?
I think that it will be a major breakthrough in the energy field for the generations to come,
but I fail to understand how at mid to long term it will be any more safe then oil.
I know oil is very bad on the environment, but if we managed to get to this point damaging earth with oil in what,
100 years, what does it change if this gets us to the same point in 300 or 400 years?
Maybe it won't pollute air and water the same way, but it still pollutes a lot!
I worry because I think energy is just like bandwidth, the more you have, the more you consume.
and then, you need more. So if it still produce a fair amount of damaging garbage, ain't it bad in the long term anyway?!?
Well, I'm not to coherent this morning, but I am just asking
I'd rather be sailing...
"Renewables" are improving, but still can't do the job properly
Not so, according to a USDA study, ethonol yields a 34% energy gain ( USDA REPORT FINDS ETHANOL IS ENERGY EFFICIENT)and that is including growing and harvesting. Wonder what the efficiency of oil is when you figure in transport from who knows where and add the cost of defending it?
I think there are better sources of energy that are just on the horizon but I think ethonol is a good temporary solution. It has enviornmental benifits and I think its better than subsidies for farmers (and taxpayers).
Why have 1 person driving a backhoe when you could employ 20 with shovels?
You don't know much about science at all. Do you really think it's appropriate for you to be spouting out pet environmental theories given your stupendous lack of knowledge of basic mechanisms of energy transfer?
Did you bother to read the article to see how this works? No.
But that sure didn't stop you from rushing out and writing a post about the potential environmental horrors of the release of ammonia gas.
Conservatives and big oil don't have to destroy the environmental movement...their own stupidity is quite sufficient for the task.
(Just as well, really: any energy we extracted from it would be orbital kinetic energy. Draining that is bad, since it would cause the orbit to decay and squish people.)
Not quite, the energy is from the relative angular speed of earth's rotation and of the moon's orbit around earth. The angular momentum of the orbiting moon is a good bit larger than that of the spinning earth, so in the end we'd slow down earth's rotation and speed up the moon in it's orbit a bit until eventually the angular velocity is the same, i.e. day and month are identical.
However the power density to be got from the tidal wave is not high enough to be extracted efficiently. There is a nice comparison of alternateive energy sources in "Gerthsen Physik", the conclusion is that only solar power, nuclear fission and nuclear fusion have enough fuel available and offer high enough power density to support man's growing energy demands.
Alternative sources like wind energy are great for local supply, especially in remote areas, but don't scale up enough to suport everyone.
Alex
Heisenberg may have been here