Creating Power From Wasted Heat 186
Roland Piquepaille writes "Today, about 90 percent of the world's electricity is created through an indirect and inefficient conversion of heat. It is estimated that two thirds of the heat used by thermoelectric converters are wasted and released. But now, researchers from the University of California at Berkeley have found a new way to convert this wasted heat into electricity by trapping organic molecules between metal nanoparticles. So far, this method of creating electricity creation is in its very early stage, but if it can scale up to mass production it may lead to a new and inexpensive source of energy."
New source of power ? (Score:5, Insightful)
Re:New source of power ? (Score:4, Insightful)
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Just look at at this previous SlashDot article: http://hardware.slashdot.org/article.pl?sid=07/02
I wouldn't worry about the computers.... (Score:5, Insightful)
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Re:New source of power ? (Score:5, Interesting)
I mean, hell. If this works well, it could be used as a component in hybrid vehicles; they only have 25% efficiency on the gasoline engine, and if they're parallel types, the heat generated by the gasoline engine could be used to keep the electrical engine in juice.
It might even be possible to recapture a bit of energy off the moderate heat generated in the electrical motor.
Of course, there will be the thermodynamical morons in here, trying to say that this little device is next in the step towards the latest self-powering promise, drawing energy from the zero point or whatever other perpetual motion bollocks is being flouted these days.
Here's a hint guys: you can't win and you can't break even. You can only take your income (solar energy) and savings (batteries, fuels, and nuclear fuels) and spend it (burning fuel or running electrical equipment). If you can boost your output per unit input, great stuff - but please don't assume it means you've hit a lotto (perpetual motion) that doesn't exist.
Re:New source of power ? (Score:5, Funny)
Obligatory (Score:2)
"Lisa, in this house we obey the laws of thermodynamics!"
Re:The point of the robot... (Score:5, Insightful)
Yeah, they insulate their houses to save on energy bills just 'cause.
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The people who always bring up the impossibility of perpetual motion lose the argument before it even begins, since they fa
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Toyota claims 45% for the Prius. I don't believe them, but one of the advantages of a hybrid is that it can keep the gas engine in the most efficient part of its working range. On top of that the availability of low-end torque from the electric system frees designers to use low-torque designs like the Atkinson (or Miller) cycle which are more efficient.
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The Holy Laws of Thermodynamics aren't being violated, the source of energy is just different.
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Just about anyone who buys gasoline and knows that the hood of the car gets hot can understand that if that heat were used to help move the car, s/he'd need to buy less gasoline.
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Wake me up when someone beats Carnot
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Doesn't the toast need to be taped to the cat's feet instead? If the toast is taped to the cat's back, the cat will simply land on its feet and walk away with the toast intact (since the toast never touches the floor at all, the buttered-side-down rule would not be invoked)
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I think OP is talking about the cat's continuous struggle to get the buttered bread off of it's back.
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Not true. It's called Combined Cycle Power Generation.
The waste flue gas from the gas turbines heats water that then powers steam turbines.
Open that fridge! (Score:5, Funny)
I could really dig have a lower electricty bill in the summer rather than a higher one. When can I build a house with this stuff?
Re:Open that fridge! (Score:5, Funny)
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Seriously though, I wonder what the limits are to this. Like, could you use this on solar panels (behind the solar cells) to suppliment the normal solar electricity generation? The cells only convert, what, 5% of the light to electricity. I'm sure the panels get hot. Hot enough to drive this new tech?
-matthew
generation vs consumption (Score:3, Insightful)
who cares if we figure out, say, how to meet 10% of our energy needs with new tech when our consumption rises 10% (or more).
a lot of "new energy" isn't really energy. as others have pointed out, hydrogen, is really just a way to transport energy.
it occurred to me recently, that, collectively, humans are like any other organism. we cannot control ourselves from the inside (something to do with goedels theorem maybe), and thus we will overrun the planet until we choke on ourselves -- or run out of energy. so i don't worry about it too much.
oh. whoops. depressing cold day here in st louis today.
mr c
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Why not conserve that additional 10%?
Low powered CPU cores, higher efficiency appliances, LED light bulbs, and similar efficiency improvements could see that personal conservation isn't needed for several years.
I dunno. Are you one of the sorts who oppose things like thorium-based reactors for political reasons rather than on their merits?
Re:generation vs consumption (Score:5, Insightful)
1. No more incandescent bulbs.
2. Live 10 minutes away from work in a condo/apartment instead of the suburbs in a giant house
3. Stop leaving your computer on all day
Actually, #2 is about the only one that really saves the most money. Smaller places cost less to heat/cool, and not driving as much saves a huge amount of energy.
But, oh environmentalists are more concerned about prohibiting housing developments or zoning that actually makes sense.
Environmentalists? (Score:4, Interesting)
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White LEDs, 30-45 lumens per watt off the shelf, 131 in the lab. And way more expensive.
http://www.netl.doe.gov/ssl/faqs.htm [doe.gov]
http://www.cree.com/press/press_detail.asp?i=11508 34953712 [cree.com]
http://members.misty.com/don/lede.html [misty.com]
Right now the reason to use LEDs is if the environment is harsh (vibrations, impacts, etc.) or if you really, really don't want to change the light often (traffic lights, or that %^#@!! bulb over my stairs). LEDs also scale down bett
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CF are great for that.
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Better batteries are where the money should be going. Really good long life rechargeable batteries make all the alternate energy sources far m
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was possible. Newer technology makes it much easier. It is just a matter
of having a smart electronic ballast and a way to communicate the dimming commands. Some ballasts for regular fluorescents have a 0-10V input, X-10 control, or other electronic input. Some ballasts
also can work down
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So is oil, when you get down to it.
Doesn't make hydrogen any more or less viable.
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who cares if we figure out, say, how to meet 10% of our energy needs with new tech when our consumption rises 10% (or more).
It a heck of a lot better than having our consumption rise and not having a better way to deal with it...
Who cares if we find a cure for cancer when people are just going to die in car accidents?
Technically... (Score:2)
We're not lowering our demand of consumer electricity, we're lowering the demand of fuel source for the amount of supply generated.
The market didn't do a thing to help stop... (Score:3, Insightful)
Ya, maybe if we had waited say a few hundred years it might have "corrected", as the remaining few non m
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So yes his comparison is perfectly justified, for the problems in question you yourself seem to admit no capitalistic solution by your failure to actually challenge his point.
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By that measure all goverment "for the people" is socialism, perhaps the stigma attached to socialisim is why goverment "for the people" is so uncommon these days.
If we accept the idea that rivers are "private" then someone polluting a private river still pollutes everyone else's "property" who lives downstream leaving you in the same position of having to impose government regulation to stop someon
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To regulate "for the people" means to do "the people's" bidding with "the people's" best interest at heart. One of those interests would be "freedom", but freedom fro
Not by trapping molecules actually... (Score:5, Informative)
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Re:Not by trapping molecules actually... (Score:5, Informative)
But fundamental to thermodynamics is that you can not have a cycle more efficient than the Carnot Cycle http://en.wikipedia.org/wiki/Thermodynamic_cycle [wikipedia.org]. This give a max efficiency = 1-(TEMPlow/TEMPhigh), so you always want that low temp to be as low as possible - for a car engine that would be the ambient air. If you have your device, then the hot side is on the engine, and the low side is in the air. But the device itself will get hot, an you will have to blow a lot of air on the cold side to keep it cold. It you let the whole device rise to the same temperature you get no conversion.
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You don't want insulators (Score:2)
Then you burn the fuel hotter and need more cooling - but there is a point where it is very useful and I've seen ceramic cylinder liners (partially stabilised zirconia) for truck engines around ten years ago. You can't take it too far - the all ceramic engine project was a failure for Mercedes due to the expected high cost of each engine and the extra weight for the larger cooling system. A mix of ceramic and
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harder and the engine fries faster when the radiator fails. Plus you are possibly reducing the carnot efficiency of the engine. But if you splice it into the hose between the engine and the radiator, you get something. The exhaust manifold does offer a significant temperature differential, though it would probably fry the device and overheat the manifold (due to the insulating effect).
What do you do wit
Indeed- it's only a smallish breakthrough... (Score:2)
benzenedithiol: 8.7 microvolts/K
dibezenedithiol: 12.9 microvolts/K
tribenzenedithiol: 14.2 microvolts/K
To put this in perspective with what we already have in the way of commonly used thermoelectric materials, Bismuth Telluride weighs in at -287 microvolts per degree Kelvin for N-doped material and 87 microvolts per degree Kelvin for P-doped material.
What we're reading about is roughly 1/5th as efficient at doing thermoelect
Heh... This is what I get for posting late... (Score:2)
Needs must have SOME sleep before posting- but then, this IS Slashdot, right? >:-)
Just ignore the post... (Score:2)
Not enough caffene, not enough sleep. Time to go to bed.
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Of course, looking at their picture you see hundreds of atoms of gold for every organic molecule.
But maybe they can make the device cheaper by using cheaper metals and only cut the efficiency
from something like 2% to 1%. And the thing probably melts a lot quicker than the old fashioned
thermoelectric modules. Not to mention that "nanotechnology" tends to be a short way of saying
not remotely economically
2nd Law (Score:2, Interesting)
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Re:2nd Law? Try the 3rd law (Score:3, Informative)
The 2nd law just basically states that any energy conversion process cannot be 100% efficient, AKA "entropy".
In effect, this is adding a secondary process to the first (or possibly list of processes), of which we already know some amount of energy will escape due the 2nd law.
This additional process just makes the overall process
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If you cool the radiator to gain energy using this device, then you'll decrease the efficiency of the primary device.
e.g. if you connect this to the radiator at the back of your fridge, then your fridge will be less efficient.
I don't know whether the net gain is positive or negative though.
Um hello. Not new. (Score:3, Informative)
Invented almost 200 years ago. I have a huge box full of Peltier "chips" sitting in my store room..
Awesome! (Score:5, Funny)
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Re:Awesome! (Score:4, Funny)
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Wouldn't it be nice if that were true? Then we wouldn't have anything to worry about, we could just go back to shopping and MTV and everything would be just peachy.
Unfortunately, the existence of man-caused global warming isn't just the concensus view of the scientific community anymore; now even the oil companies and (gasp!) the Bush administration admit the existence of the problem: the evidence is that irrefutable. So if y
Kurt's Law (Score:2)
And yet... (Score:3, Interesting)
the Carnot efficiency of 86% for a combustion temperature of 2000 centigrade.
And even the reamining "waste" heat could be used if better planning happened:
district steam, drying and other industrial uses.
Cogeneration (Score:2)
After my lecture classes, while I was in American doing my thesis at a coal-fired power plant, I told my coworkers about the district heating systems which exist in almost every city back in Sweden. One of them joking said, "Sounds like a bunch of Communism to me." You know what? It is.
While it saves incredible amounts of money on fuel (which doesn't come from the
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Community ownership (Score:2)
For US, it sounds like a perfect fit for the "designed" communities.
Way to save energy.. (Score:2)
But this brings up another idea. Why not do away with burning fuels for heat. Large building could instead burn fuels to generate electricity and use the waste heat as their heat source. Extra ele
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Large thermoelectric plants are ~40% efficient. A burner heats water, the steam passes over a turbine (connected to a generator), the steam is then condensed (where all the energy is lost) and pumped back into the water tank so it can be heated again.
My suggested idea would, most likely, use an internal combustion engine at ~25% efficiency. But even
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That may work in some place, some of the time. In most places that extra heat will have to be vented out somewhere as you don't want your house to be a furnace. Back in NY we shut off the heaters as the small amount of heat coming from the pipes passing by the walls, good insulation, sunlight and our own heat production more than sufficed (I had to open
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* 100 if you're metric.
Energy from waste heat (Score:2)
Good to see (Score:2)
Waste heat density same as solar heat (Score:2)
Sounds like a job for... (Score:2)
If this works (Score:2)
Not a big deal (Score:4, Informative)
Firstly, there is a theoretical limit (Carnot Cycle [wikipedia.org]) to the efficiency of any pure heat engine based on the Second Law of Thermodynamics.
If a quantity of heat Q is taken from a high-temperature reservoir at temperature T2, partially converted into useful work W, and the remainder (Q - W) is deposited into a low-temperature reservoir at temperature T1, then the net increase in entropy is at least
\delta S = (Q-W)/T1 - Q/T2 >= 0.
So the efficiency (useful work generated per unit energy input)
e = W/Q < (T2 - T1)/T2
The waste heat is ultimately deposited into the environment, so T1 can't be much smaller than say 300K.
In a steam engine T2 has to be greater than the boiling point of water (at whatever pressure it is operated), but it is limited by what the materials of which it is composed can withstand. Temperatures of order 1000K are typical. That gives a maximum theoretical efficiency of around 70%. The best steam engines barely reach about half that efficiency.
However, modern power plants (which are not pure heat engines) use a Combined Cycle [wikipedia.org] that can do better by first generating electricity from their fuel with a combustion turbine and then using the waste heat from the combustion turbine to make steam to generate additional electricity via a steam turbine. Their efficiency can reach about 60% of the net calorific value of the fuel.
So you can see that one might be able to shave a few more percentage points off the waste, but it will not at all be the godsend we really need...
IMHO only nuclear power can fulfill that role today.
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One question though. Isn't a gas turbine just another heat engine that that is governmed by the limits of any thermodynamic c
"Wasted" heat is not available for this device. (Score:5, Informative)
Re:"Wasted" heat is not available for this device. (Score:4, Interesting)
In a hydroelectric dam, you can convert a portion of the potential energy of water flowing downhill into work. You can only convert the energy when the water is flowing downhill and you cannot convert all of the energy because that would stop the water from flowing. The maximum efficiency is the head difference (high and low water points). Unless the low point of the dam is at sea level, you are not getting all of the potential energy out of the water.
The 2nd Law of Thermodynamics and Carnot Efficiency have the same major points. You can only convert some of the heat to other work while it is moving from hot to cold and the maximum efficiency is the difference in the high and low temperatures relative to absolute zero.
As the parent post pointed out, power stations attempt to exhaust condensation heat as close as possible to ambient temperatures and there isn't much "waste" heat to recover. If there was an efficient thermocouple device like the article, its use would be in all the industrial waste heat from sources that are currently too small to justify existing heat recovery systems.
Do the math, Carnot cycle, economics, etc.... (Score:2)
This means "do the math". Figure out how much energy is captured, at what cost, over what period of time. You also need to figure out the true opportunity costs-- what are you giving up if you go down this path. Not to mention calculating the risks and uncertainties.
With most if not all schemes for capturing energy from small temperature differrences, the efficiency is soooo small, that the schemes can never even
The real story here... (Score:3, Informative)
Anyone have a spare first year thermo textbook (Score:2)
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[slashdot.org]http://science.slashdot.org/article.pl?sid=02/05/1 5/1810211 [slashdot.org]
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Always remember: Most research doesn't work out. Over half of proposed new developments die at every stage of development. (Well, that's probably an artifact of how the stages were defined...but there were, I think, 6 of them.)
OTOH, the occasional research that pays off is where all new developments come from, whether faster RAM or new devices for increasing power availability.
Still, you're right to remember that this device is at the "laboratory bench" s
Re:What? (Score:4, Interesting)
Anyway, my point, after reading TFA, it became pretty obvious that this stuff would work like a thermocouple, but you could fit many of them over a large area. It's isn't so much "nano-magic", as it would be a miniaturization of an idea that sees daily application. It sure would be cool if they get it functional.
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The current is low and the voltage is low so you don't get much power from this - but it does work.
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Get a laptop (or a laptop cpu) or one of those small via things, oh wait you want cutting edge performance AND low heat production.
How about a power supply that only draws as much power as is required to run the attached equipment?
What the fuck DO you think power supplies do, baring some minimal constant loss?
How about a respectably sized solid state hard drive to replace the millions of spin
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Why yes, I do.
"What the fuck DO you think power supplies do, baring some minimal constant loss?"
Funny you should mention it right after suggesting a laptop. The power supply for my laptop, a transformer with DC rectifier, does not in fact match consumption with load. Neither do the millions of others like it.
How about something a little more constructive next time?
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Then you make no sense, to do that would require lowering what constitutes cutting edge (ie: performances at the cost of everything). If you do that then you may as well just buy a less than cutting edge system and in the end you come out mostly the same. That statement would only make sense if there were no lower power options yet there are, and power consumption is a major problem for chip makers (when its not you get things like the cray).
Neither do the millions of others like it.
Yet again
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You seem to have no idea about the fundamentals of electricity. Electricity is supplied from the mains at some higher voltage, say 120 or 240V, and through passive transformers or active power electronics is converted down to a lower voltage, say 18V or so.
When the power supply is disconnected from the load, there is obviously no current flowing through th
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temperature differential gets added to your CPU junction temperature. To overcome this, you would
need an enormous heat sink to reduce the heat sink to ambient loss.
In the winter, the heat generated by the computer heats your house which reduces the waste. In the summer, however, you AC has to work harder. You could save a substantial amount of energy by hanging your PC out the window.
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the direct heat contribution is dwarfed by the indirect effects.