Thermoelectric power plants could offer economically competitive renewable energy

December 19, 2014 by Lisa Zyga feature
A thermoelectric power plant might use energy harvested from ocean waves to pump cold water up through a heat exchanger/generator near the surface. The heat exchanger is made of thermoelectric materials which can use the temperature gradient between the warm and cold water to generate electricity. Credit: Liu. (CC BY 3.0)

(Phys.org)—A new study predicts that large-scale power plants based on thermoelectric effects, such as small temperature differences in ocean water, could generate electricity at a lower cost than photovoltaic power plants.

Liping Liu, Associate Professor at Rutgers University, envisions that thermoelectric would look like giant barges sitting in the tropical ocean, where electricity is generated by heating cold, deep water with warm, shallow water heated by the sun. Liu has published a paper in the New Journal of Physics in which he analyzes the feasibility of such power plants.

"This work is about the new idea of large-scale green power plants that make economic use of the largest accessible and sustainable energy reservoir on the earth," Liu told Phys.org, speaking of the oceans. This is because the sun heats the to a temperature that, in tropical regions, is about 20 K higher than water 600 m deep. Essentially, the surface water acts as a giant storage tank of solar energy.

As Liu explains, thermoelectric power plants would work by harvesting the energy of ocean waves to pump cold water from a few hundred meters deep up through a long channel. As the cold water nears the surface, it enters a where it is heated by surface water on the outside. The heat exchanger acts as an electric generator, as its tubes are made of that can transfer heat through their walls and directly convert temperature differences into electricity.

Large-scale, ocean-based thermoelectric power plants would have many advantages. For one, the "fuel" or temperature differences are free, unlimited, and easily accessible. Also, the plants do not take up space on land. Because they have no moving solid parts, they would have low maintenance costs. In addition, the power output does not depend on the time of day or season. And finally, the method is green, as it does not release emissions.

A thermoelectric power plant can also use geothermal sources to produce the temperature gradient. Here, hot water is pumped up to the heat exchanger/generator, where it is cooled by air. Credit: Liu. (CC BY 3.0)

Small-scale thermoelectric generators are already used commercially in applications such as microelectronics, automobiles, and power generation in remote areas. In these designs, the conversion efficiency is the most important factor because the fuel accounts for the largest portion of the cost. Most commercial devices have a conversion efficiency of around 5% to 10% of the ideal Carnot efficiency, with state-of-the-art devices achieving efficiencies of up to 20%. Although research is currently being done to further improve the efficiency, there are still limits to how high it can go.

In the new paper, Liu shows that large-scale thermoelectric power plants wouldn't need to operate at extremely high efficiencies to be economically competitive; instead, the key would lie in engineering simple structures such as laminated composites in order to support mass production. These improvements focus on the conversion capacity, which, unlike efficiency, can be improved by orders of magnitude. In other words, because the fuel is free and in limitless supply, large-scale thermoelectric power plants could make up with their sheer size what they lack in efficiency.

The cost of generating electricity varies by source. According to the US Department of Energy, the estimated cost per year of one megawatt of electricity in 2016 is about $0.83 million for conventional coal plants, compared to $1.84 million for photovoltaic power plants. Liu's analysis estimates that a thermoelectric power plant could generate electricity for less than $1.84 million, although an exact estimate is difficult at this stage. This estimate is for a thermoelectric generator that lasts for 20 years and uses ocean water with a 10 K temperature difference as fuel. If water from geothermal sources is used instead, the temperature difference could be 50 K or more, resulting in an even higher power gain and lower cost per watt.

Overall, the analysis shows that thermoelectric power plants look very promising and could contribute to solving the world's energy problems. Liu plans to work toward this goal in future research.

"We are currently working on experimentally validating the predicted power factor of the thermoelectric composites," Liu said. "Once this is validated, we will seek to fabricate a table-top prototype of the generator that uses ice water and hot as 'fuel.'"

Explore further: Toward a low-cost 'artificial leaf' that produces clean hydrogen fuel

More information: Liping Liu. "Feasibility of large-scale power plants based on thermoelectric effects." New Journal of Physics. DOI: 10.1088/1367-2630/16/12/123019

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Shootist
2.3 / 5 (12) Dec 19, 2014
Might as well go fund Rossi.
Modernmystic
2 / 5 (5) Dec 19, 2014
How to you transmit the power you make?
TheGhostofOtto1923
3.7 / 5 (14) Dec 19, 2014
Might as well go fund Rossi.
Hes already very well-funded with his first commercial plant in operation.
How to you transmit the power you make?
Uh undersea cable?
antialias_physorg
4.6 / 5 (9) Dec 19, 2014
For one, the "fuel" or temperature differences are free, unlimited, and easily accessible.

For a given value of 'unliited'. (OK, the potential here is so vast that it makes next to no difference)

How to you transmit the power you make?

Depends on how close to shore you can site this. With a steep descent direct link powerlines might be within reach. Further out you'd probably want to convert to some intermediary carrier (e.g. hydrogen) and pump that through pipes. Still further out you could store locally and occasionally send a tanker 'round to collect.
antonima
1 / 5 (1) Dec 19, 2014
I've always thought a great place for thermoelectrics would be the north pole. There is only a thin layer of ice between water at -2 and the ambient air which must be a lot colder most of the year.
TheGhostofOtto1923
4.3 / 5 (11) Dec 19, 2014
We could guess like aa or we could take a minute and look up power transmission solutions from engineers.

"Provided that the temperature differential is fairly constant, OTEC should run on its own. The world's biggest Ocean Thermal Energy Conversion plant will be built off the coast of China by Lockheed Martin. The 10MW offshore plant will be built to power a new green resort and test the system as a whole. Data from this plant will be used to make adjustments for efficiency and power output, which will make future installations, up to 100MW, easier to design and implement. Lockheed Martin estimates that a 100MW OTEC plant could offset 1.3 million barrels of oil and cut carbon dioxide emissions by 500,000 tons."

"Transmission solutions for connecting offshore power plants to the onshore grid"
http://www.diva-p...XT01.pdf
sstritt
5 / 5 (2) Dec 19, 2014
This is a very old idea. We covered it in an oceanography class I took in 1979!
Modernmystic
1 / 5 (2) Dec 19, 2014
Uh undersea cable?


Yes, my thought too. What about storms (part of this is on the surface), This would severely limit how far out to sea you can use this too. Are we going to string power cables halfway across the pacific basin? What about maintenance on a system like that? If you go to deep (and I'm talking a few hundred feet) you need specialized equipment to deal with it.

With all the off shore wind etc, stuff like this is actually going to get real estate intensive even in the middle of the water, because you're going to want to do it near population centers that can handle the power being produced.

I'm not saying it's not doable at all. I'm sure it's quite doable. I think it's worth pointing out the possible issues with it though.
Modernmystic
not rated yet Dec 19, 2014
Thanks for the link Otto, maybe I should to a little more self research before just asking sometimes :P
gkam
2.7 / 5 (10) Dec 19, 2014
If they build it, it will be interesting to see how the upwelling water brings nutrients to the surface for life activity.

What happened to the original OTEC?
antialias_physorg
4.5 / 5 (8) Dec 19, 2014
Are we going to string power cables halfway across the pacific basin?

As I said: there are regions where the ocean floor drops off steeply close to shore. There cables are quite feasible (off shore windparks are also connected to land with cables, and laying such cables isn't exactly new nor high tech). For "halfway accross the pacific" such a cable would make no sense. But there's little reason to go that far out (and even if you want to - theer are other methods of getting the energy back, as noted)

With all the off shore wind etc, stuff like this is actually going to get real estate intensive

Since off shore wind likes shallow waters (due to the need to anchor the windfarms) and this system requires deep waters - the two aren't incompetition over the same realestate.

I think it's worth pointing out the possible issues with it though.

Cost vs. benefit will be the final deciding factor. The setup seems cheap enough, so it might actually be worth it.
Modernmystic
4.2 / 5 (5) Dec 19, 2014
What I find most attractive about a system like this is that the promise of the article of "cheap cost" seems to actually fit. We've all heard about cheap solar and cheap wind. What's never talked about are the fantastically huge feed in tariffs and the fact that, at best, they're only producing 30% of the time...in effect making even the best current cost estimates off by a factor of 100%.

THIS on the other hand seems very straightforward, easy to produce, no rare earths, low maintenance (assuming several things) AND most importantly highly reliable and dispatchable...IOW something that has a chance of actually working.

I guess we'll just wait and see.
sstritt
1.3 / 5 (3) Dec 19, 2014
This might be promising as a propulsion system for large vessels. It would elliminate difficulties of transmitting power to shore.
timothee400
3 / 5 (1) Dec 19, 2014
There has been an idea for a better and more efficient way of converting low grade heat to electricity for some years...check out energy-inventions.com
TheGhostofOtto1923
3.7 / 5 (6) Dec 19, 2014
As I said: there are regions where the ocean floor drops off steeply close to shore. There cables are quite feasible (off shore windparks are also connected to land with cables, and laying such cables isn't exactly new nor high tech). For "halfway accross the pacific" such a cable would make no sense. But there's little reason to go that far out
AA still prefers to ad lib as if a few moments of idle musing can match in-depth studies from experts and engineers which they ought to know must exist.

You didnt read the link. READ the LINK. Youll see cables stretching across the north sea.

What I find most baffling is that it just doesnt occur to some people that, with subjects like this, OF COURSE real engineers would have written papers and designed systems, and that this would OBVIOUSLY be available on the internet.

But they risk looking silly by guessing. Makes no sense unless you consider hubris or just lazy.
PeakSpecies
1 / 5 (2) Dec 19, 2014
The thermoelectric effect has been well known for at least 100-years. Despite a great deal of work the efficiency hasn't been improved much. The highest efficiency material tend to be very expensive and depend on rare-earth materials. It is well known that low temperature gradients tend to result in poor thermodynamic efficiency. The scheme would involve moving massive quantities of saltwater long vertical distances. The analysis apparently doesn't take the cost of the power transmission cables into account either. In general it seems to be more based on speculation rather than proven hardware. It is typical for engineers to not figure in the biological disruptive cost of their proposed schemes.
Modernmystic
5 / 5 (2) Dec 19, 2014
What I find most baffling is that it just doesnt occur to some people that, with subjects like this, OF COURSE real engineers would have written papers and designed systems, and that this would OBVIOUSLY be available on the internet.

But they risk looking silly by guessing. Makes no sense unless you consider hubris or just lazy.


No, Otto, they're not failing to be you. They just do things differently. Don't take it so personally or with such angst...
eachus
1.3 / 5 (6) Dec 19, 2014
I wish that the global warming hysterics could at least be consistent. Nothing wrong with this approach as a way to generate power, although in many locations, OTEC with ammonia or CO2 as the working gas will be more cost effective. (Depends not only on the temperature difference, but also the source and sink temperatures.)

But to someone who believes the AGW hysteria, this should be anathema. Think of all the low-lying countries that will be submerged! This would actually reduce the time, measured in centuries, for deep water to get heated. Not significantly, but still.
Code_Warrior
not rated yet Dec 19, 2014
I don't know anything about how the cold water at the bottom is replenished. My knee jerk reaction is that it gets replenished through the freeze/thaw cycles at the poles, but that's a wild guess on my part. I wonder how much cold water area is affected by one of these plants? Would cold water necessarily flow into the area to replace the amount pumped out? I know the top layer of water would cool, but the newly heated water that was brought up from below is warmer and has to go somewhere. Where does it go? Could it possibly stay local to the plant such that a circulation is formed locally between the surface water and the water at depth that would work to equalize temperatures locally and reduce the power output? I'm asking because I don't know. I would hope that the replenishment cold water would come from the surrounding area which would in turn ultimately get replenished by the freeze/thaw cycles at the poles, but I don't know enough about it.
JRi
not rated yet Dec 19, 2014
Algae growing on thermoelectric heat exchanger may lower efficiency quite soon. They propably have proposed a solution for that in their paper, tho.
gkam
2.3 / 5 (6) Dec 19, 2014
Why run the pipes so far down, when all you have to do is run wires to the junctions and provide a little assist to the convection currents set up there??
Wake
not rated yet Dec 19, 2014
Don't you find it interesting that people are complaining about global warming and to fight it they suggest a manner in which to cause absolutely MASSIVE environmental damage?
Consultofactus
5 / 5 (1) Dec 19, 2014
As many have pointed out - the concept is well known and well within the state-of-the-art as it exists today. But it will never happen because the greenies will have seizures over thermal pollution.
crusher
not rated yet Dec 19, 2014
If they become very common and are used on a very large scale they might cool the atmosphere by pumping up cold water from the bottom of the ocean to the surface. It will cool the topics and the trade w9inds might get cooler and make it rain more.
Water_Prophet
1 / 5 (3) Dec 19, 2014
Just me, but wouldn't doing this solar be more effective?

And much less effective than solar?
Urgelt
1 / 5 (3) Dec 19, 2014
I don't mind if this technology gets developed. The more competing methods we have of producing clean power, the better.

But ocean kinetic looks to my untutored eye to be a better candidate technology for investment, if we can solve materials and design difficulties. I do hope to see more engineering ingenuity going into tapping it than is currently happening.
etudiant
5 / 5 (2) Dec 19, 2014
There have been OTEC efforts for about a century. They have all failed.
The cause was either structural failure, large components overstressed by wave action, or heat transfer failure, because of bio fouling of the heat exchangers.
Afaik, the latest such effort, off Hawaii, has now transmogrified into a designer water producer, peddling 'hyper-pure' deep ocean water desalinated for the Japanese market. They gave up on power production.
mvogell
not rated yet Dec 19, 2014
The deeper cables are, the less trouble they are. 1 cm diameter fibre optic cables in 20,000 feet of water and 15 cm diameter cables plus buried 6 feet deep to keep from being damaged by draggers- depth isn't the problem.

At best windmills are only producing power 30% of the time. I think that is an average, not a top amount. I know for a fact that some operate more than 30% of the time.

I like the idea of using cold air (Arctic/winter) and the warm(er) water of the ocean.
dev_dangol
1 / 5 (1) Dec 20, 2014
If we make correction of the mistake there has been on hydropower engineering we wouldn't need any other sources of power at all The cleanliest power will be available by cheapest possible way we can think of

At present we are tapping only minimum hydropower by applying the principle of still water column that it exerts highest pressure at the bottom, so we run only one turbine at the bottom of the running water column The property applies in standing still water column only It is a blunder in hydropower engineering In hydropower we have the running water condition The pressure effect in a running water column is uniform throughout, from intake to discharge points Considering the properties of uniformly running water column, it is possible to run many turbines in series along a single uniform penstock pipe We have to keep water running consistently to maintain constant revolution of the turbines Uniformly running water column has uniform velocity and pressure throughout
antialias_physorg
4.4 / 5 (7) Dec 20, 2014
uniformly running water column, it is possible to run many turbines in series along a single uniform penstock pipe We have to keep water running consistently to maintain constant revolution of the turbines Uniformly running water column has uniform velocity and pressure throughout

You can't cheat physics that way. The total energy extractable is still m*g*h. And the total power is dependent on how much mass you can feed into the system per second.
Having many turbines does not give you an advantage (it's only a disadvantage due to much higher maintenance). .
teslaberry
1 / 5 (1) Dec 20, 2014

wave commercial electric generation power is dead and needs to stay dead as it was the day it arrived.

engineering scale size systems floating in the ocean is hard enough for pumping out highly dense energy resoivoirs of oil. the sheer amount of physical water that would need to be pumped per useable output btu of heat difference/gradient to drive the output on a thermoelectric stack is hard to just ignore.

it's impractical and environmentally dubious at best to pump that sheer quantity of water through any system, especially one as violent and large as the general ocean surface and a deep column below it

though naive global warming alarmists will point that this would effectively pump heat of the ocean to the deep waters (by drawing up cold water and mixing it with warmer)
TheGhostofOtto1923
3.7 / 5 (6) Dec 20, 2014
What I find most baffling is that it just doesnt occur to some people that, with subjects like this, OF COURSE real engineers would have written papers and designed systems, and that this would OBVIOUSLY be available on the internet.

But they risk looking silly by guessing. Makes no sense unless you consider hubris or just lazy.


No, Otto, they're not failing to be you. They just do things differently. Don't take it so personally or with such angst...
No, I think pretense and laziness are intrinsically offensive. Don't you? AA would be offended if I pretended to know something about software engineering. And yet he seems to think his phd gives him special insight into unrelated disciplines.

This behavior is sadly pervasive among overeducated people. It hinders the free dissemination of knowledge.

I'll continue to expose this sort of nonsense because it is important and also satisfying.
Going
not rated yet Dec 20, 2014
When the system is becalmed no cold water will pump up from the ocean depths. So not a completely uninterrupted supply
Moebius
not rated yet Dec 20, 2014
We have a clean inexhaustible source of heat energy below our feet. Why isn't anyone smart enough to realize we can reach it? If we can go 100's of thousands of miles up to the moon we can figure out how to go down a few miles.
danmatk
not rated yet Dec 20, 2014
Ok.. so put lipstick on OTEC (ocean thermal energy conversion) and call it something new? Didn't they do an OTEC demo in Hawaii 20 years ago?
dev_dangol
1 / 5 (1) Dec 20, 2014
uniformly running water column, it is possible to run many turbines in series along a single uniform penstock pipe We have to keep water running consistently to maintain constant revolution of the turbines Uniformly running water column has uniform velocity and pressure throughout

You can't cheat physics that way. The total energy extractable is still m*g*h. And the total power is dependent on how much mass you can feed into the system per second.
Having many turbines does not give you an advantage (it's only a disadvantage due to much higher maintenance). .


To,
antialias_physorg

# Running turbine does not decrease the power of running water. Quantity of discharge of water is not altered even after running turbine. So far you have water running, the force involved "G" is constant so, no matter how much water you make fall. Thus power of running water at a given point remains constant. I am not, you are cheating Physics.

Bob_Wallace
not rated yet Dec 21, 2014
What does this mean?

"the estimated cost per year of one megawatt of electricity in 2016 is about $0.83 million for conventional coal plants, compared to $1.84 million for photovoltaic power plants"

Is this overnight costs or installed costs? $83,000,000/MW of coal and $1,840,000,000/MW of solar? $0.83/watt and $1.84/watt.

$1.84/watt installed is about right for utility scale solar in the US. It was $1.81/watt at the end of Q2, 2014. Should be a bit lower now and will almost certainly be lower in 2016.

The DOE database states from $1.92/watt to $8.42/watt for overnight coal. Median $3/watt. Roughly double that for installed coal (lots of accumulated interest during construction). Their coal price makes no sense to me.

Mike_Massen
2.6 / 5 (5) Dec 21, 2014
Elsewhere Water_Prophet claimed
They show everything you need to know about why CO2 doesn't work
That is ONLY from Sol to Earth, U miss SO MUCH !

WHY Water_Prophet do U REFUSE to look at absorption/re-radiation of Earth to Space ?

You seem to have a very serious reading/comprehension neglect bias problem !

Please FOCUS on these SIMPLE questions, do U accept:-

1. Your TSI graph ONLY shows Sol to Earth - largely Shortwave (SW) ?

2. Earth converts SW to Longwave radiation (LW) ?

3. Negligible SW is emitted to space ?

SIMPLE logic by way of SUBTRACTION re energy PROVES LW to space is CORE issue !
.
.
.
Water_Prophet, these is a VERY simple issue, WHY do U ignore it & look intellectually feeble ?

Please be GENUINE & smarter & not come across with some form of disability... :-(

I await the clarity of response a real Physical Chemist (PC) can actually muster to this link:-
http://phys.org/n...day.html
Code_Warrior
5 / 5 (3) Dec 21, 2014
Running turbine does not decrease the power of running water. Quantity of discharge of water is not altered even after running turbine. So far you have water running, the force involved "G" is constant so, no matter how much water you make fall. Thus power of running water at a given point remains constant. I am not, you are cheating Physics.

Conservation of energy. The water gives up its energy to the generator. Stacking generators along the height of the water column doesn't increase the energy output because the load attached to the generator creates resistance to the turbine's rotation which, in turn, creates a pressure drop across the turbine. The sum of the individual turbine pressure drops can't exceed the maximum available water pressure which is Height X Density X G. At most, the sum of the pressure drops across the turbines can only equal the max available pressure and that's only if the pressure drops across the interconnecting tubes are negligible.
MR166
not rated yet Dec 21, 2014
One would think that barnacles and algae would be be a huge problem in something that has a huge surface area like this. Flow and heat transfer would soon be reduced. The sea is a harsh environment and structures placed there are very expensive to maintain.
Mike_Massen
3 / 5 (6) Dec 21, 2014
dev_dangol claimed
So far you have water running, the force involved "G" is constant so, no matter how much water you make fall. Thus power of running water at a given point remains constant. I am not, you are cheating Physics
No. In Physics there is a proven relationship between power, torque & speed ie Power = Torque x Speed & it has been known for well over 150 years Eg Steam !

Look at the placement of turbines on hydro stations, they r almost all as close to the bottom as possible as the potential energy of the fall (mgh) becomes torque & the more often you can deliver that the faster turbine spins & those two multiplied gives you power !

Power, whether from Torque x Speed or Volts x Amps is the SAME, that's the very nice part of the precise definition of power and works well through Physics.

Actually iirc, its only high-school physics, here in Australia we get a grounding in it when students are 14 - 16 yrs of age, think U are due a refresher...
dev_dangol
1 / 5 (1) Dec 21, 2014
dev_dangol claimed
So far you have water running, the force involved "G" is constant so, no matter how much water you make fall. Thus power of running water at a given point remains constant. I am not, you are cheating Physics
No. In Physics there is a proven relationship between power, torque & speed ie Power = Torque x Speed & it has been known for well over 150 years Eg Steam !

# similarly you install another one without breaking continuity of the water column, I suppose you know the series system or method.
teslaberry
not rated yet Dec 22, 2014
stick with solar panels . how about that.
Mike_Massen
2.6 / 5 (5) Dec 22, 2014
dev_dangol claimed
..similarly you install another one without breaking continuity of the water column, I suppose you know the series system or method.
No. Learn irrefutable physics 1st.

If anything came even CLOSE operationally as U claim U would have a perpetual motion machine, ie use first turbine as pump to add same mass of water to top, whilst using lower turbines to generate power - doh - doesn't happen - NOT possible in THIS universe !

TRY understand high school physics, converting potential energy to kinetic energy, rate of delivery is Power.

FYI a turbine converting pressure/flow to power ADDs resistivity, water dynamics almost direct exact analogy to electrical dynamics re resistance, flow, power etc. Adding a resistor makes sure U have less power flow, your 'idea', was touched on > 150 years ago, backyard garage tooled inventors tried it doh guess what discovered physics, cest la vi

Education is SO important, it saves time & moves forward :-)
Code_Warrior
5 / 5 (3) Dec 22, 2014
# similarly you install another one without breaking continuity of the water column, I suppose you know the series system or method.

As I already pointed out to you, the sum of the individual pressure drops across the series connected turbines can't exceed the maximum available water pressure at the bottom of the water column. The flow rate will be determined by the sum of the individual turbine flow resistances and the max pressure at the bottom of the water column. The system of turbines will fill with water and none of the turbines will spin until the pressure across a turbine exceeds the force required to drive its generator's load. As each turbine begins to move, the pressure drop across it will subtract from the pressure available to the next turbine in the series. At equilibrium the power output of each generator will be limited by smaller pressure drops in exactly the right proportion that the sum total output is the same as a single generator at the bottom.
antialias_physorg
5 / 5 (3) Dec 22, 2014
And yet he seems to think his phd gives him special insight into unrelated disciplines.

Disciplines I have studied? Like electrical engineering (which has a pretty solid founding in math and physics...and not only the physics that is relevant to electricity is taught there). Yeah. Studying stuff to the point where one can actually apply it does give one a special insight that cannot be had via google. Similarly I have tried to get a bit of education in astrophysics, though not anywhere near some of the best posters here (yyz, axemaster Q-star, et. al) . In the end I voice an opinion which I try to support with facts. What's your excuse?

But you may have notice that I stopped blasting you (not because your posts have gotten any better - just because physorg put in this nifty 'ignore user' feature. And you would not BELIEVE how fast I clicked that for your name. Only verkle beat you to that illustrious list). So back on ignore you go :-)
nizzim
not rated yet Dec 22, 2014
This sounds like a great idea. I don't really get how the transfer process works but if we can extract the warm water on massive scales maybe we can circumvent ocean warming? At the same time generating electricity.
dev_dangol
not rated yet Dec 23, 2014
TO
Code_Warrior
Mike_Massen

Forget present practice based on the property of standing water column Develop new engineering based on running water column Shape of the blades I am not an engineer but can help

Conservation of energy
# energy is transmitted to rotate turbines not decreased Water is running continuously G constant

creates a pressure
# How Pressure is never dropped If dropped turbine will be slow or velocity of water will be reduced

the pressure drops across the interconnecting tubes are negligible.

# How much is available No decrease Height Density Water Velocity G is never reduced or displaced

less power flow
# Each section of the running water column get same pressure effect - Bernoulli Theory

next turbine in the series
# no way to drop pressure but by only change in height which is also fixed for a given installation

CLOSE operationally
# don't do it

pressure drops
# no it does not How do you know it drops

Code_Warrior
5 / 5 (2) Dec 23, 2014
less power flow
# Each section of the running water column get same pressure effect - Bernoulli Theory

Yes, each section will get the same pressure effect and the sum of those pressures can't exceed the pressure at the bottom of the water column. If you have 10 identical turbines stacked for a total height of H, and take the density of water to be 1 gram/cubic centimeter, each turbine will have a pressure H*1*G/10 = H*G/10. A single turbine at the bottom of a water column of the same height H will have a pressure of H*G. You do the math.
pressure drops
# no it does not How do you know it drops

The force required to rotate the turbine works against gravity to support some of the weight of the water so that the water that exits the turbine doesn't have the full weight of the water above or inside the turbine bearing down on it. Therefore the water pressure at the turbine exit is lower than that at the entrance. In other words, there is a drop in pressure.
antialias_physorg
5 / 5 (4) Dec 23, 2014
dev_dangol

Here's an idea for you. Try it out. You know: real physics. You don't need much. You can try it out while in the shower by holding one hand under the stream and then doing the same with two hands one above the other- letting the runoff from one hit the other one. Notice how the force you feel is the sum of the force you felt for one hand?

If you're still not convinced you can rig up a real power producing setup probably in less time than it has taken you to post - with all-household items.
imido
Dec 23, 2014
This comment has been removed by a moderator.
Code_Warrior
5 / 5 (2) Dec 23, 2014
Forget present practice based on the property of standing water column Develop new engineering based on running water column Shape of the blades I am not an engineer but can help
The existing generation techniques ARE based on a flowing water column, you can't generate power from standing water, THERE MUST BE FLOW AND PRESSURE TO GENERATE POWER. The pressures developed at the bottom of a full water column are the same whether the water is flowing or standing.
next turbine in the series
# no way to drop pressure but by only change in height which is also fixed for a given installation
Ok. Think of it that way if you like. In the example in my previous post the change in height = H/10, the pressure drop is (H/10)*G = H*G/10.
creates a pressure
# How Pressure is never dropped If dropped turbine will be slow or velocity of water will be reduced
Change in height as you just stated, unless you want to argue with yourself.
Code_Warrior
5 / 5 (1) Dec 23, 2014
Conservation of energy
# energy is transmitted to rotate turbines not decreased Water is running continuously G constant
Yes, G is constant and the flow through all turbines is the same and the energy transmitted to each turbine is lost by the water and shows up in its pressure drop, which is related to the change in height of the water as you have realized unless you want to argue with yourself.

As antialias_physorg has suggested, build a model yourself using tabletop parts and try it out.
leathernuts
5 / 5 (2) Dec 23, 2014
How will this effect warming ocean temperatures? If we are unnaturally heating the water, what are the global impacts? We often rely on the Gulf Stream system, which allows the weather to be less chaotic. any introduced heat could negatively impact this.
MR166
not rated yet Dec 23, 2014
That thought occurred to me also. In reality the amount of change that a system like this could produce is miniscule.
Modernmystic
not rated yet Dec 23, 2014
IMO thermoelectric plants are economically infeasible as such, but they could be also utilized for extraction of heavy metal elements from marine water, like the gold and uranium.


Interesting. Do you have any data to back that up? I'm not saying that as a challenge or to be pissy :) I'm honestly interested if you've seen anything to suggest it.

It would seem (on the face of it) to be very economically viable. There would be few moving parts, it could be made of very inexpensive material, minimal regulatory hoops to jump through for the tin plated dictators of the energy sector, no rare earths (AFAICS)....seems pretty cheap to me.
antialias_physorg
5 / 5 (2) Dec 24, 2014
How will this effect warming ocean temperatures?

Good question. at first I would guess: Not much. Since you're not introducing energy, but working on energy that is already there. The temperature balancing will happen whether you do it through a contraption like this or whether you just leave the ocean be.

What does happen is that you coool down surface layers and warm up lower regions. This means lower regions will be somewhat less oxygen rich while surface layers will become oxygen richer (solubility of oxygen depends on temperature).
(What this means for CO2 solubility I have no idea off hand.)

One has to take into account that this would be VERY regional (the ocean is BIG). So the overall effect would probably be quite minute - even if this were to be adopted as the single, global source of energy (which we shouldn't. It should be part of a mix if it's economically viable).
dev_dangol
not rated yet Dec 25, 2014
TO
Code_Warrior
Mike_Massen
End conversation Last reply Don't agree Up to you Turbines don't move up and down Rotate at a fixed place I AM Told efficiency of turbine is more than 98% Almost resistance free Water flows without resistance Slickest substance (GBWoldRecords) between film of water ADSORBED (not absorbed) on the walls of penstock pipe No matter what materials made of

Try experiment
Water meter Model turbine Shows RPM and Q They are all calculated in actual turbines Can be connected as many water meters as we want Connect at least one meter at the top, One in the middle and Another at the bottom Observe and calculate if they all discharge equal amount of water. All the water meters must show equal reading, it has to be so even for common sense as well At least, that is the result I got every time I did. I have them in my blog as video clips to show how it is done in series connection
THANKS FOR YOUR INTEREST
Best wishes
Dev

Mike_Massen
1 / 5 (3) Dec 25, 2014
dev_dangol claimed
..experiment
Water meter Model turbine Shows RPM and Q They are all calculated in actual turbines Can be connected as many water meters as we want Connect at least one meter at the top, One in the middle and Another at the bottom Observe and calculate if they all discharge equal amount of water
Of course those "meters" (if designed well) will show much the same speed depending on their accuracy & resolution assuming they are designed primarily as instruments, because these are ONLY "meters"; I expect antialias_physorg, Physics & I have no problem with metering :-)

Do U understand distinction between a speed meter & a turbine designed for power ?

Note:
1.Meter (instrument) designed to interfere with flow as little as possible.
2.Turbine designed to extract as MUCH power as possible therefore interferes.

Have you thought just WHY your idea hasn't EVER been implemented since hydropower was imagined well over a hundred years ago ?

cont
Mike_Massen
1 / 5 (3) Dec 25, 2014
Modernmystic asked
..it could be made of very inexpensive material, minimal regulatory hoops to jump through for the tin plated dictators of the energy sector, no rare earths (AFAICS)....seems pretty cheap to me
The economics have been worked through rather thoroughly for a long time & its just not worth it. If however, U used your own capital on your own estuary/beach and U were the ONLY one to maintain it & process electrodes or even buy your own ion exchange resin then you might enjoy it & maybe collect some heavy metals to gain some satisfaction of accomplishment but, for the amount of time spent alone, you would make far less money than flipping burgers at McDonalds.

Even where there might be so called waste power (somewhat rare) the "net present cost" is far higher than income possible from selling any metal collected - methods either via ion exchange resins or electrolysis. In this respect, economies of scale make the relative effectiveness even worse !
Mike_Massen
1 / 5 (3) Dec 25, 2014
@dev_dangol
cont
All the water meters must show equal reading, it has to be so even for common sense as well At least, that is the result I got every time I did
Please extend that common sense a bit further & appreciate the Science of Engineering is soundly based on Physics, otherwise devices just wouldn't work - unless U believe it pendants with 'crystal power' ;-)

Basic physics in terms of fundamentals re Power & Torque are KNOWN for hundreds of years, just because we have more advanced engineering in last 100 yrs doesn't defeat basic Physics.

Meters are engineered ie Specifically Designed to interfere as little as possible with quantity being measured.

Eg. Tachometer on a car engine, if the engine is in neutral & you rev it to 5000 rpm it ONLY shows engine speed, no power delivered.

Can U see the distinction now re your experiment ?

dev_dangol claimed
I have them in my blog as video clips to show how it is done in series connection
You have a link ?
Mike_Massen
1 / 5 (3) Dec 25, 2014
Elsewhere Water_Prophet expounded by showing us example of Hypocrisy
The biggest problem is from pretenders or people with no education who spout their opinions out, which is fine, but then deny even when they do not know, and of course are uninterested in learning or even considering a fact that contradicts their opinion
Agree fully with that pattern.

Your opinion Water_Prophet that CO2 is not significant re TSI is correct, agree with U :-)

People who graduated as a Physical Chemist (PC) of which Water_Prophet claims, should KNOW energy flows in 3D, so Y do U completely IGNORE Earth's emissions which any person with intelligence & Physics training easily determine it MUST be overwhelmingly Long Wave (LW) ie. Plain to "see" Short Wave (SW) from Earth is negligible !

Why do U ignore LW, where CO2's absorbance/re-radiation is the HIGHEST ?

Water_Prophet muttered
..having only a fork's understanding of how the food tastes
What does this even mean re U?
dev_dangol
not rated yet Dec 25, 2014


I have them in my blog as video clips to show how it is done in series connection

TO
Code_Warrior
Mike_Massen

Search by the name dev bahadur dongol. The title of the blog is - solution to climate change and power crisis, turbines don't decrease the power of running water
dev_dangol
not rated yet Dec 25, 2014
TO
Code_Warrior
Mike_Massen

I have them in my blog as video clips to show how it is done in series connection
You have a link ?

devbahadurdongol.blogspot.com

Mike_Massen
1 / 5 (3) Dec 26, 2014
dev_dangol claimed
dev bahadur dongol. The title of the blog is - solution to climate change and power crisis, turbines don't decrease the power of running water
Series do !
Mate, try understand. I & others trained in Physics R not trying to dissuade U getting an education, we are earnestly showing U basic physics & maths is VERY WELL KNOWN for >100 yrs, we are trying to save U valuable time & effort & ultimate disappointment in what appears to be your emotional attachment to ideas not fully formed, sorry U desperately need to get prepared before U even think of claiming what U have on this thread :-(

I specifically asked U re this question:-
Meters are engineered ie Specifically Designed to interfere as little as possible with quantity being measured.

Eg. Tachometer on a car engine, if the engine is in neutral & you rev it to 5000 rpm it ONLY shows engine speed, no power delivered.

Can U see the distinction now re your experiment ?
Answer please ?
Mike_Massen
1 / 5 (3) Dec 26, 2014
Elsewhere Water_Prophet claimed
How can you say I ignore longwave radiations?
By evidence U ignored long wave (LW) radiation re CO2's interference to space, U only saw TSI.

U write fossil fuel (FF) proportion of TSI, yet U IGNORE FACT Earth converts short wave (SW) to LW & CO2 interferes with emission to Space. Nobody is disagreeing FF adds heat & CO2. But, U, as a claimed Physical Chemist (PC) haven't acknowledged CO2's interference U even claimed "CO2 is a red herring", which is obviously completely WRONG !

Water_Prophet claimed
..1998 was a very hot year; Industry was booming and the Sun was at/near a max
Huh? U claim Sun TSI was at max ? Not according to this
http://www.skepti...asic.gif

Water_Prophet claimed to be a PC, yet doesn't write like one, does Water_Prophet accept:-

1. TSI mainly SW
2. Earth converts SW to LW
3. LW to space interfered by CO2

Simple issue Water_Prophet I asked before, WHY do u STILL evade ?

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