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Creating Power From Wasted Heat
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."
How is this "a new source of power" ? it's just improving efficiency by reducing loss.
So now instead of yelling at my kids for leaving the fridge door open I'll have to get them to leave it open every now and then in order to keep the electricity bill down.
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?
Organic particles between nano metals? How about a Stirling engine invented 200 years ago?
"But now, researchers from the University of California at Berkeley have found a new way to convert this wasted heat into electricity [...]. 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."
In other words, the "but now" is unwarranted, since there's still waste heat and no practical way to harness it. Until then, it's just "Researchers are attempting a practical way to waste less heat."
I haven't even touched on the excessive use of "but", "could", "may", etc. in recent summaries.
The Urban Mover company I pre-ordered an electric bike from are working on a hydrogen fuel cell that converts heat to electricity initially for their scooters but will probably see cars being powered too.
Anything in the electricity generation area that improves upon previous methods of squeezing as much power out of your fuel souce can only be a Good Thing[tm].
To do something right, you often have to roll up your sleeves and get busy.
we've seen a lot of "new energy" stories on /. today, and there's been a lot of talk in the media lately, too. but NO ONE is talking about conserving energy. of course, this is an american perspective, and self-constraint is unamerican as it gets.
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
"Physics is like sex. Sure, it may give some practical results, but that's not why we do it." - R. Feynman
I hope no one here will forget about the 2nd law of thermodynamics...
http://en.wikipedia.org/wiki/Thermoelectric_Effect
Invented almost 200 years ago. I have a huge box full of Peltier "chips" sitting in my store room..
"However, such thermoelectric generators operate at a paltry 7 percent efficiency, compared with the 20 percent efficiency rate for traditional heat engines. Moreover, such converters are made up of exotic, expensive metal alloys, such as bismuth and tellurium, making them too costly and impractical for widespread use."
Its an organic peltier... nifty. Wonder if it works as well as a heat pump.
So this means global warming is a good thing. With all the electricity we'll be able to make, it's no problem to just run enough air conditions to solve the problem.
Want to improve your Karma? Instead of "Post Anonymously", try the "Post Humously" option.
I've come up with a new law: The odds of an announcement regarding an "inexpensive source of energy" having a disclaimer that "this method of creating electricicty creation [sic] is in its very early stage" approaches one as the amount of energy in the proposed invention increases, and/or as the cost decreases.
Computers still are, and probably always will be, a fairly small fraction of electrical consumption. Yeah, data centers are all the way up to 1%... But 1% is 1%. Not a big component... Hell, I'd be more concerned about this - if we replace fossil fuel cars with electric in the next fifty years, electric power used to recharge vehicles will probably become one of the biggest fractions of the total load.
Have you been touched by his noodly appendage?
"You're exactly right. But the common man doesn't understand 'efficiency gains' as something significant. Perceptually, people don't get how much energy is lost to waste heat."
Of course we do. Every time someone farts, that's energy lost.
I think the 3rd law is more appropriate here, since they are basically talking about using the waste heat of an earlier process, and converting part of it to usable energy.
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 more efficient, and does not really add to it above the original process's input energy. However, the 3rd law just states you can't achieve 0 entropy in a process with a finite number of steps. Basically, you can never have a process that is 100% energy conversion efficient.
Probably the more important question is does the increase of enthalopy merit the proposed decrease in entropy? AKA, does the cost of implementing this solution outway the benefit.
Cogeneration only wastes about 1/3 of the energy. That's not too far off from
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.
Were that I say, pancakes?
Every one of us has something we use daily that generates massive supplies of waste heat - our car engines. Instead of releasing it to the atmosphere with radiators and fans, couldn't we convert some of it to electricity with some sort of small turbine? If we did that, we could use it to help power the car with a hybrid motor. Kind of like regenerative braking, but the energy source is constant. I would love to get that extra heat as torque for my Camaro! Maybe I could get on dragtimes.com
"Be grateful for what you have. You may never know when you may lose it."
Producing electricity from a heat source (gas, coal, nuclear) is wasteful - typically only ~40% efficient. So in order to maximize our use of resources we should make use of that wasted heat. Pumping the heat (via water) to neighboring houses and greenhouses is just one example that is commonly used in Europe.
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 electricity could be sent to the grid at nearly 95% efficiency. I say 95% efficiency because almost all the the energy released by the burning fuel is put to work.
In warmer climates this approach would be less useful, but it would still be effective for heating water. An entire block of building could get together and share a single generator/hot water heater.
Anyway, this is just a thought resulting from seeing large buildings in cold weather being heated via natural gas while knowing that the electricity powering the building was only 40% efficient.
Willy
Whatever happened to PV cells? Are we just gonna give up on those becoming a reasonable reality (i.e. not cost prohibitive)? Wait, I got it, lightning bugs! Harness their power!
Somebody go! Somebody go! God almighty, somebody go!
a heatsink with the ability to change processor heat into electricity. It could be used to cycle back extra energy into the PSU while cooling itself. Less noise, less electricity. Or having engine walls with this material, to replace the altenator/magneto.
Isn't that called cogeneration?
http://img140.imageshack.us/my.php?image=perpetao4 .swf
...water pollution. Nothing. Zero. It took serious government regulations in a lot of directions at the federal, state and local level and mass civil indignation to do that, because the "market" ALL found it cheaper-better for their "shareholder value and bottom line"- to just dump their toxic waste wherever they felt like it and to transfer health care costs to -anyplace else, downstream usually.
Ya, maybe if we had waited say a few hundred years it might have "corrected", as the remaining few non mutants rose up finally and bumped off the remaining few mass polluters who were left, but for some reason society decided to step in with some stricter laws before it got that bad.
I could name numerous other examples but that is an easily seen one.
Sometimes you just can't wait for the "this quarter's profits" mentality boys to do the right thing. Some things might need to be addressed now, once they are clearly understood to either be a problem now or soon will be, as opposed to waiting around for a long time in an economic and social experiment to see what might happen. And believe it or nuts, there are more important things on this Earth than some corporation's bank balance.
That is not to say that government can't be hugely overbearing and infested with generic mass stoopidity itself,of course it is,I speak out about government abuses all the time, but "the market" is no better really, neither extreme -leave it all to the market (caveat-emptor brand corporatism would be the extreme there) or all to the government(cult of the personality one leader-one party-mass bureaucracy and no one even wants to work any longer except under the whip"- ism government would be the extreme that other way)- is the end all or be all of "solutions". I think what we have more or less constructed- at least semi-regulated markets and at least an attempt at a semi-regulated society via this government thing-is probably the best humans can do at our (barely out of the medieval level intellectually or psychologically) evolutionary stage.
Of the two extremes and the middle, the middle is what we mostly have and falls under the lesser of the three big evils choices. It is imperfect, absolutely no doubt there, but the best we can do right now. What we can do is to keep chipping away at the imperfections on a case by case basis.
"Lisa, in this house we obey the laws of thermodynamics!"
Find environmentally and socially responsible products on http://buy-right.net
"But the common man doesn't understand 'efficiency gains' as something significant."
Yeah, they insulate their houses to save on energy bills just 'cause.
Good to see that some professors can both do research and teach without lacking in one or the other. Professor Majumdar's a nice guy, his heat transfer class was very well taught, really helped get me interested in heat transfer as something to elaborate on for MechE.
The main problem in recovering energy from a diffused source with a small temperature diff over the surroundings is the little thing called Carnot limit efficiency. If the alleged technology is really succesful there is no need to limit it to waste heat. We could apply it equally well to solar energy collection too. But sadly, looks like the alleged device is a very low efficiency thermocouple.
sed -e 's/Chuck Norris/Rajnikant/g' joke > fact
Since we are so inefficient at converting heat into energy, could this possibly contribute to global warming? If we are using so much heat to convert to energy, how much of that wasted heat just heats the atmosphere instead of making energy?
Someone could make a killing if they harnessed all the wasted heat produced by Congress.
Sanitaion might be a problem though, since they all talk out of their asses.
Knowing Google's lust for data collection, the Soviet Union is still alive and well inside the psyche of Sergey Brin....
...a traditional heat engine like a Stirling Engine. I just trust something I can take a wrench to more than a convoluted biological solution that has biosystem requirements.
we can generate power for the entire nation by fitting out the halls of Congress. Finally -- a good use for all that hot air!
The contest for ages has been to rescue liberty from the grasp of executive power. -- Daniel Webster
Unfortunately, thermoelectric converters based on the Seebeck effect are not going to help with efficiency by a large amount.
Firstly, there is a theoretical limit (Carnot Cycle) 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 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.
The "wasted" heat that thermal power plants reject to the surroundings is rejected at a temperature only slightly above ambient. A steam turbine generator has an exhaust steam condenser which operates at a vacuum, where the steam condenses at only a few degrees Fahrenheit above the ambient temperature. There is no significant temperature difference available for the new device to operate with. While thermal power plants do reject over half the fuel energy consumed to the surroundings, it is a myth that this rejected heat can be effectively used. The rejected heat is available at a low temperature, only slightly above ambient, therefore little effective use can be made of it. This is the penalty that the laws of thermodynamics impose on the conversion of heat into work.
What's your sample to say what "oh environmentalists" are concerned with? Consider Portland, OR, where environmentalists put in zoning to pack housing into the center of town and prohibit it from sprawling farther out. (True, the anti-environmentalists lately threw a wrench into that with a misleading statewide referendum.) Or on the other side of the country, environmentalists in Vermont are also encouraging more housing in and close to traditional town centers rather than sprawling across the countryside. What is your sample set of "environmentalists" who prefer that we'd all live in suburbs in giant houses? I'd suggest that whoever you can find fitting that description just flies a flag of convenience - the evil often cloak themselves in the names of the good.
"with their freedom lost all virtue lose" - Milton
I think he means there is a difference between understanding it's a waste when the heat you are paying for is going out the window, there is a very direct cost. It's less likely for people to think that the heat coming out of the back of their vacuum cleaner is also wasted energy. Electrical appliances get hot when they run, right? Nothing unusual about that.
We hope your rules and wisdom choke you / Now we are one in everlasting peace
Adding to your point #2:
Smaller place - less to heat/cool (and furthermore, typically you have only 1-3 exterior "walls" vs. a minimum of 5 for a house, meaning that your radiant environmental stabilization is being re-cycled by your neighbors in a condo or apartment, and being completely wasted in a house).
Not driving as far (and typically, better access to mass transit.. less energy to get to/from work, school, shopping, etc.)
Also, when trash pickup is done for your apartment there's one truck that takes 2 minutes to get the weeks trash (and recycling) from hundreds of families -- unless you live in a house and that costs hundreds of times as much energy per family.
For those that don't give a hoot about these "environmental" reasons to live in a smart space there are other advantages to an apartment in the city vs. a house in the burbs:
more time for yourself -- less time stressing out in traffic jams.
you don't need to mow the lawn, water the flower beds, rake the leaves, or shovel the snow.
you might actually get to know some of your neighbors.
I'd like to see what others can add (or detract) to/from this post!
Be who you are and say what you feel, because those who mind don't matter and those who matter don't mind. - Dr. Seuss
I believe I saw what might pass for Zt values given for the stuff in another article:
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 thermoelectric effects as the most efficient stuff we have for P-doped material at the consumer level- which isn't really all that efficient, but is useful enough if you're needing cooling or thermoelectric generation in tight spaces that wouldn't accomodate other answers. The "wow" comes from it being the Thermoelectric equivalent of an OLED back when OLEDs were still more of a lab curiosity than a sort of fielded part of the time technology.
Brass tacks here: It's NEAT beyond words, but it's not the thing the article made it out to be. It's not even as good as the best we have in Peltier devices yet.
I am not merely a "consumer" or a "taxpayer". I am a Citizen of the State of Texas
Read: ZT == Seebeck Coefficients...
Needs must have SOME sleep before posting- but then, this IS Slashdot, right? >:-)
I am not merely a "consumer" or a "taxpayer". I am a Citizen of the State of Texas
Heh... I'm so freaking tired and out of it, I didn't even notice that you'd already quoted the values, etc.
Not enough caffene, not enough sleep. Time to go to bed.
I am not merely a "consumer" or a "taxpayer". I am a Citizen of the State of Texas
I can't say much about your drivel other than you are rather bonkers. No, "socialism" didn't make General Chemical and Sludge dump toxic waste into the drinking water supply, GREED and being jerks did.
As to being a liberal, I am what is now called a "paleocon", a normal plain vanilla regular old timey Constitutionalist, and as such, I recognize the need for SOME government, because we need it. Not overbearing and bloated. I mean I started my political activism working both normal conservation issues AND on the GOLDWATER campaign. Notice root word, conservative-conserve-be a good steward. I see nothing contradictatory there. Now I did pull one year as a dues paying capital L, but left because of similar bonker theories I kept hearing about total private ownership of everything, laws be damned, etc. Nuts. they won't work in the real world because corruption-which you pointed out-is there. In government we at least have a slim chance to get the bums out, with entrenched corporations whcih invariably fall into cartels and monopolies-you can't get rid of them! Freaking vampires! And their track record? Dismal. We are forced into a lesser of evils stance, some government, some market, case by case basis following our old simple laws works the best.
No, I don't want your corporation owning all the water, no thank you, nor the air,no thank you. They failed it, proof is in the pudding, they had their chance and blew it bigtime, and even today, even with regulations they are still pretty sleazy about it to save a buck for themselves.. And I sincerely doubt most other people would think your switch to corporations owning everything and "leaving it up to the market" is a good idea either. We dumped "snakeoil" as a concept, because that is what happened, mass snakeoil from "the market". And that's not a strawman, that's as direct as it can be put. No, I reject your corporatist company store model total private ownership of every single possible thing theories. Some things, not everything, but some important things, are better left to the commons, and to be protected by the commons. Our founders thought so as well, that is one of the main reasons for having a government in the first place! The major rivers, etc, "owned" by the people in the states they went through, not by ACME Rivers inc., equaly shared out to the middle for the people, for general usages, and we finally realized as a society that because of asshat corporate water polluters, to use my exact point again which fits perfectly as an example, the jerks who just refused to stop, so we needed to slap some regs on them, because..well..they were asshats about it, they screwed up royally when left to "market forces", because in a lot of cases "market forces" just won't work, that is just proven past data back from when we didn't have regulations about such things, they all just dumped crap willy nilly, and it caused *problems* that "the market" wasn't addressing.
For some things they do,markets work just fine and no one cares if you make a buck, that's the deal we all work under, for others they don't, we need a little common government action, and it is as simple as that.
my dog is the ultimate in power conservation. she gets energy from consuming her own heated waste.
"Unfortunately, thermoelectric converters based on the Seebeck effect are not going to help with efficiency by a large amount.
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."
I wish I didn't have to waste so much energy on (would be) physicists that don't realise that the second law was derived for GASSES. For other systems there are/will be other laws. E.g., mechanical energy can be converted into electricity near 100% vice versa.
We will both agree agree that 100% is the max. But never ever come up with the Second Law again unless you're talking about a conversion involving gasses and unless you don't fail to realise that this theoretical limit is what can be achieved in 1 single step. Do more steps, and you'll convert more heat into electricity (e.g. with an organic Rankine cycle).
As to the 100% max of the Second Law, I think it doesn't properly represent the efficiency in the real world. The Second Law doesn't appear to say much more than that for a gas the energy content is linear with the temperature. I believe that the 100% should be defined for no heat released in the environment (your T1 of about 300 K). If we were to calculate the efficiency of engines etc. in this way, we would have a much better idea of how much we can improve and whether that is useful.
Bert
Who realises that he's not going to cough up the money to invest the money to do all these additional steps
such a device already exists. It's called a thermoelectric generator. Here are some good links: http://www.peltier-info.com/manufacturers.html They're not very efficient, but are very reliable.
Here are some interesting thermoelectric generator apps: http://www.hi-z.com/Hi-Z.Brochure.2006.pdf
I haven't seen anyone point out the efficency of an carnot engine (car, your fridge, etc) depends on the output end being hot (the temperature difference).
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.
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 pay back the cost of borrowing the capital to build it, much less pay for maintenance, upkeep, degradation, and distributing the energy.
It matters not whether it's "wave power", or "tidal energy", or "tropical seawater", or even "sunlight". If you DO THE MATH, using realistic numbers, and assuming no hidden subsidies, the numbers are usually anywhere from marginal to extremely dismal.
Typical things ignored: reliability, labor costs, energy storage, energy transmission, cleaning, maintenance, zoning, environmental laws, land acquisition, manufacturability, cost of capital, long-term reliability, noise, and probably more..
this is a "conservation" story. We're converting stored fuel into heat energy to generate electricity. We waste much of this heat. The story is about wasting less heat. That's efficiency in the same way that CF bulbs throw off less heat (waste) and insulation in your house allows less heat to escape (waste).
We're not lowering our demand of consumer electricity, we're lowering the demand of fuel source for the amount of supply generated.
Support a few technologists in Washington.
Foreword: I am an American who dropped out of college in the US, moved to Sweden, and ended up doing an entire power engineering degree there.
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 Russian Federation, unlike nature gas) and reduces the risk of house fires, widespread district heating infrastructure exists only where the State has had full or large control over the energy infrastructure. What's more, many systems in Eastern Europe (where they are aimed at large apartment blocks, an ideal end user) are being scrapped in favor of gas not because of inadequacy, but because of privatization. This is simply a technology which can't be born into (or really even live in) a free market.
Compare this to America where public ownership has been much more limited: The majority of our cogeneration (at least during parts of the year) goes towards industry! In Sweden, which isn't that much colder than, say, Chicago, the country uses twice as much heat during an average year than electricity. Think of the possible market. There are dozens of large northern cities throughout the country with comparable weather which could benefit from a hot water district heating system--possibly even profitably so; they've certainly managed to in Europe. In addition to that, natural gas reserves are facing similar projected lifetimes to oil. Being able expand our use of our enourmous Western coal fields to domestic heating would make us less prone to import still further petroleum products from Africa and the Middle East.
Your suggestions are still pretty minor. Lightbulbs save some, commuting a bunch, your computer almost nothing, but the real culprit in energy waste is international shipping.
Boats and planes use vastly more energy than anything else we do. Moving big shipments of crap from China to the U.S. so we can throw it into a landfill here is nothing more than energy waste.
Ever been to a dollar store? *All* that stuff came from Asia in a big slow boat that uses more fuel in a month than you will use directly in your entire lifetime. You can sell your car and walk for life and you won't make a dent in our mountain of consumption.
Economically it makes sense. Fuel is still surprisingly cheap. Environmentally it's very complex... without the money from those imports, can we afford to do the research we need? Without a Western middle class, who would have enough time on their hands to worry about it?
Still, the point is that you need to keep perspective about energy use. By switching to CFLs, you're doing more to vote for CFLs than anything. The energy you save is minor, but the money you're investing in moving towarad CFLs is a big deal. The same was true with the switch to LCDs... prices dropped as more people bought them and eventually CRTs died out at most factories.
correction That should have been "...because the coolant fluid isn't heated beyond it's boiling point" The working fluid definitely is heated
One more technology for improving efficency. Post generation use of waste heat for further generation has been studied, and occasionally used for over 40 years. In the industry it is often referred to as a bottom cycle generator or bottomer. There are also toppers. They were being studied and occasionally used in the 1970's when I was in college. This is not really a new idea. It MAY be an improvement over what large coal plants are currently using. It may not. Results and time will tell.
Still, the research will go on. That's why we pay for it. With enough improvements, we may be able to squeeze another 5% efficency out of a large power plant.
Everybody knows 3 people with my name.
...is that our buddy Roland Piquepaille finally posted a story that directly summarizes and links to the information instead of telling us to come to his blog for the real story.
Remember, there were no nuclear weapons before women were allowed to vote.
Many (most?) of the district heating systems in Denmark are community owned. I witnessed it once, someone took initiative to a local heat/power plants, and got a sufficiently large fraction of the community to sign up for it.
For US, it sounds like a perfect fit for the "designed" communities.
Please send it to this Roland guy or Zonk. We're seeing a lot of these articles, and they would be a bit more coherent with a bit more basic understanding.
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 metal gives you the chance to have things hotter in the cylinder and conduct the heat away quickly with a metal engine block. You need that temperature differential to get the engine to give you more power - so insulators are not the answer.