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Waste Heat to Electricity?
Darwin_Frog writes: "Recent advances in thermionics at MIT lets waste heat generate electricity, thus pushing entropy one step further down the chain. These devices work at a temperature around 250 deg. C, instead of around 1000, so cars can augment the alternator by using the waste heat in the exhaust system to produce power for onboard electronics and A/C."
soon they'll be able to use excess heat from humans...matrix style.
less power required= less pollution
Introducing Athlon XP 5000 - Now self powered!
Wax-Museum Fire Results In Hundreds Of New Danny DeVito Statues
When an electric car can keep me warm in -40 degrees below zero, while driving against the wind for a 300 mile drive I'll be impressed.
Personally I'd put more stock in a vehicle powered by hydrogen.
According to the article, this "breakthrough" is a reverse Peltier junction with about twice the efficiency of current semiconductor thermoconverters. Nice, but nothing revolutionary.
I think it's quite excessive to claim this will reduce entropy. Although I agree that if it's economically deployed in, say, cars, it will supplement the alternator.
Could this new junction actually replace the alternator for producing electricity in a car? Let's see: assume a car has a 100 HP internal combustion engine. That's 75 kW. Two third of this is wasted in heat. Typically, the radiator gets about half of this heat (the other half is dissipated away in radiant heat or through the exhaust. Assume further that 20 percent of this can be recovered and converted to electricity (for a really efficient semicon pile). That's 75 * 2/3 * 0.50 * 0.20, or 5 kW. That's more than a good SUV alternator. So this could actually work, provided it's reliable and not too expensive.
You'll need a battery for the short runs, though.
--
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It's true, the applications for automobiles seem rather limited, but thermionics could stand to revolutionize the nature of power plants.
IANAS, but I believe that today's newest and most efficient coal, oil, and even nuclear power plants can at some point be looked at as a simple heat -> steam -> turbine system, the same concept that's powered locomotives for over one-hundred years! As you'd imagine, such a system is terribly inefficient.
Thermionics, as I understand it, eliminates the "middleman" of the equation by translating heat directly to electricity. It certainly will be interesting to see how this develops on a commerical and thus much larger scale.
With the increasingly hot processor temperatures as clockspeeds rise, and the heat generated by laptop's power supplies, etc, could this technology be used to improve the battery life of portable devices?
No, Beowulf clusters can't imagine in Soviet Russia.
My question is how much more gas mileage could this technology squeeze forth given an array of these attached to the heat producers of a vehicle, like the engine or the brake pads.
Another thing is how do these "thermal diodes" compare to a Peltier Element in heat conversion to electricity?
It'd be great if we could use this for cheap solar cells. Regular solar cells are pretty expensive. (I'm almost convinced that other industries are screwing with the market to make them cost so much). Anyhow, does anyone know how much this new stuff would cost? PS: nuclear's my favorite, but it's too easy for the govt to regulate.
Well, hybrid technology is already here. I drive a Toyota Prius (and love it!) and there's also the Honda Insight. Neither reclaim heat, however, so this may be one more may to charge the battery while the engine is running.
Chrysler has a diesel hybrid in development, a prototype called the ESX3, that currently is getting around 72 mpg. The main problem for them is *cost*. As time passes, this will go down. I don't know if they reclaim engine heat, but I doubt it.
Ford *does* have an all electric prototype but it, and any early all-electric cars would be primarily designed for the folks who want a strictly "in-town" car. This notion is already catching on in the form of NEV's (Neighborhood Electric Vehicles).
But, yes, this sort of technology will be probably be pointless within 20 years, at least for automobiles. May have some other uses, however.
In the immortal words of Socrates, "I drank what?"
Female Prison Rape in NY
- You can't win.
- You can't break even.
- You have no choice about playing.
Any closed system ends up in the state of most disorder, and all systems are closed if you look at the boundaries carefully. No matter how hard you try, no matter what ingenous things you do, in the end, the dealer wins and everything is dust. Cold dust, at that. The more energy you expend enforcing order, the more chaos you cause. There are no wins in technology, only a prolonging of the inevitable loss. So while I'm sure this new doohickey is neat, somewhere, Carnot is laughing and his cycle is tapping you on the shoulder snickering to itself.News for Geeks in Austin, TX
Actually yeah, that's what I was talking about :)
Granted that people talk about how combustion engines waste heat, but no one ever seems to adress how that very heat is neccesary for many parts of the world. I suppose with vehicles, electic cars are a good idea for those in cities that mainly would just need to drive across town, but lets face it; many people use vehicles like an SUV just to drive across town.
I couldn't help noticing that within a few paragraphs the writeup mentioned that (1) the research was partly sponsored by DARPA and (2) patents have been applied for with one already issued. Color me bitter, but as one of the taxpayers who funded the research I can't say I'm overjoyed at the prospect of paying licensing fees to MIT through the eventual commercial implementors.
I'm all in favor of government-sponsored research. They have the resources to investigate stuff with great benefits but staggering R&D costs. I'm all in favor of universities conducting the sponsored research. Grad students are cheap (I know, I was one for many years) and the brainpower is not less than one finds in industry. However, when the government pays a university to do something new, the university's benefits should be the equipment bought for the research and the prestige that comes from doing it first/best/cheapest.
Learn to spell: nickel, missile, lose, solely, amendment, speech, kernel, probably, ridiculous, deity, hierarchy, versus
this truly is the fundamental question: can this be made to be more efficient than a turbine/generator combo?
If this can be more efficient than a turbine, we can have solid-state power plants. Nukes are nothing more than a complex method of boiling water to push a turbine: if we can replace the water, we have an order of magnitude less waste! Not to mention that the core stuff is much easier to deal with than heavy water. Plus, with no pumps or pipes to break, it becomes even safer than it already is.
Or other things, say laptops? PDAs? Naturally all these kinds of applications are XYZ years off, but just imagine what would happen when we get the effiency of these things up? I'd bet that boiling water to turn a turbine is real low efficiency: if we cut out the turbine step alone, that should increase effiency by a whole lot.
This is truly cool shit.
These things don't kick in until about 250 Celsius, 482degrees Fahrenheit. Which is pretty fucking hot already :P
Who knows, maybe with better materials it might someday be practical for use in PCs, but not for a while.
autopr0n is like, down and stuff.
And it came to pass that AC learned how to reverse the direction of entropy.
But there was no one to whom AC might give the answer of the last question. No matter. The answer---by demonstration---would take care of that, too.
For another timeless interval, AC thought how best to do this. Carefully, AC organized the program.
The consciousness of AC encompassed all of what had once been a Universe and brooded over what was now Chaos. Step by step, it must be done.
And AC said, "Let there be light!"
And there was light---
Isaac Asimov, The Last Question
The Raven
It's nice when people come up with better technology, but the inefficient use of energy in the US right now is not a technological problem, it's a political problem. Let's hope that we'll eventually be doing well enough that it will really become a technological problem.
I don't know about you, but where I live the sun dosn't head surfaces to 480 degrees Fahrenheit...
autopr0n is like, down and stuff.
I mean "heat surfaces."
autopr0n is like, down and stuff.
Doesn't a 100HP (75kW) internal combustion engine actually consume 300HP of chemical energy to make its 100HP of mechanical energy if it's 33% efficient? So the waste heat would be 200HP or 150kW.
Putting moderation advice in your
You *might* extend battery life for a small length of time (measured in tens of minutes at the most) by recycling some of the waste heat, but entropy still rules. You cannot recycle all of the waste heat, so you will be unable to run your device for anything close to indefinitely.
-Legion
Here's the reference for that one!
General Relativity: Space-time tells matter where to go; Matter tells space-time what shape to be.
The Toyota Prius actually *does* reclaim heat. It does so while braking, converting the energy that normally would be transferred to the brake pads, to aid in charging up the half of the engine that is electric. So this theory is useful, and is currently in practice. I saw a report on TechTV about it. The car employs a process called "regenerative braking, which reclaims up to 30% of this waste heat, and helps charge up the batteries of the car. www.techtv.com/freshgear/story/0,23158,3357682,00. html
I hate sigs.
When dealing with vehicles of any kind, the primary problem is that the energy source has to be portable. Therefore, you need a source with a high energy density. In other words, something that you can get a lot of energy from while it takes a small amount of space. Even more importantly, you want the energy in a form that you're going to use it in, or as close as possible to such a form, because conversion of energy causes a loss of energy.
To date, combustion based systems have the highest energy density of any portable energy source (barring fission reactions). Therefore, there will always be a use for it.
Perhaps automobiles won't necessarily need them - we can afford to carry additional weight - the fuel/weight ratio for automobiles is evidence of this - you can carry a LOT with a small amount of fuel for a car - and you can then drive for a long time.
But what about flying vehicles? Fuel/weight ratio is EXTREMELY important. The more efficiency that we can get the better. The best part about this is that it might remove the need for an alternator, which drains the power and adds weight to any flying device (which is significant for the small vehicles, such as the automonous surveyor helicopters used by the U.S. military). Improvements in fuel usage can mean a big deal for the aircraft industry.
Of course that's not the only industry that will benefit. Heat-differential technology is used as a power source for some areas...have you heard of geothermal and solar power plants? Know how those work? What if they could double their output? That would be significant.
Mod me down and I will become more powerful than you can possibly imagine!
Wouldn't it have been easier to say "40 degrees"?
-Legion
The 1st problem with this technology is the high temprature 400C is a material science problem.
The next is the poor overall efficiency. MIT says they get 2X times the efficiency. From Photonpower.com I remember a 5% efficiency, so lets be generous and claim 15% efficiency.
Yet, with the use of stirling engine technology A $90 750Watt engine or the mystical Ginger or IT you can use waste heat and get power. Stirlings will move with as little as a 2C temprature difference. 90% as a CHP is possible
If you want to get excited about the idea of heat/electricity, then go take a look at some Naval research that could provide room grade AC w/o state change presently used.
But this technology? Not that exciting, and that is ONLY because of the high temprature.
If it was said on slashdot, it MUST be true!
I know this is way off topic, but I had to post it somewhere. About ten minutes ago (9:16 MSDT) I happened to see something explode over West Texas crossing the sky. Not like anyone really gives a rip, but it was cool! Looks like it was heading a little north of east and I would guess it's near Arkansas by now. Main object flamed yellow and four smaller objects below flaming red. Spooky!
I couldn't care less what gets done with that energy... put a nice fluorescent light inside the case or something.
Many of the comments posted make the connection of generating electricity from the heat that the CPU produces, However, the heat being produced is actually caused because of inefficiencies in transistor switching. So if transistors became more efficient they would would waste less electricity and generate less heat thus needing less electricity leading to less heat leading to needing less electricity until we are actually generating electricity from the lack of heat.
"A person is smart. People are dumb, panicky dangerous animals and you know it." - K
Not too much info yet. In particular, there's no indication of how much such devices will cost per watt. This is a basic problem with things like Peltier-effect devices and solar cells; they work fine, but you need an awful lot of them to get serious power levels. If this requires something like a wafer fab to make, it will be a niche device for years to come.
Yeah, you know me!
For the unintiated, MC Hawking lyrics follow.
MC Hawking is Stephen Hawking, physicist and gangsta rapper. Despite three critically acclaimed albums and nearly ten years on the mic, Stephen Hawking remains virtually unknown as a musician. mchawking.com is devoted to Stephen Hawking's career as a lyrical terrorist.
Harm me with harmony.
Doomsday, drop a load on 'em.
Entropy, how can I explain it? I'll take it frame by frame it,
to have you all jumping, shouting saying it.
Let's just say that it's a measure of disorder,
in a system that is closed, like with a border.
It's sorta, like a, well a measurement of randomness,
proposed in 1850 by a German, but wait I digress.
"What the fuck is entropy?", I here the people still exclaiming,
it seems I gotta start the explaining.
You ever drop an egg and on the floor you see it break?
You go and get a mop so you can clean up your mistake.
But did you ever stop to ponder why we know it's true,
if you drop a broken egg you will not get an egg that's new.
That's entropy or E-N-T-R-O to the P to the Y,
the reason why the sun will one day all burn out and die.
Order from disorder is a scientific rarity,
allow me to explain it with a little bit more clarity.
Did I say rarity? I meant impossibility,
at least in a closed system there will always be more entropy.
That's entropy and I hope that you're all down with it,
if you are here's your membership.
Chorus
You down with entropy?
Yeah, you know me! (x3)
Who's down with entropy?
Every last homey!
Defining entropy as disorder's not complete,
'cause disorder as a definition doesn't cover heat.
So my first definition I would now like to withdraw,
and offer one that fits thermodynamics second law.
First we need to understand that entropy is energy,
energy that can't be used to state it more specifically.
In a closed system entropy always goes up,
that's the second law, now you know what's up.
You can't win, you can't break even, you can't leave the game,
'cause entropy will take it all 'though it seems a shame.
The second law, as we now know, is quite clear to state,
that entropy must increase and not dissipate.
Creationists always try to use the second law,
to disprove evolution, but their theory has a flaw.
The second law is quite precise about where it applies,
only in a closed system must the entropy count rise.
The earth's not a closed system' it's powered by the sun,
so fuck the damn creationists, Doomsday get my gun!
That, in a nutshell, is what entropy's about,
you're now down with a discount.
Chorus
Hit it!
Doomsday, kick it in!
Peter L. Hagelstein was the guy at MIT who had MIT's lawyers churning out cold fusion patents like there was no tomorrow at the same time that MIT's official position was that cold fusion was an illusion -- and making official recommendations against its funding.
Seastead this.
Example: You put a heat-based gizzmo on your car's exhaust pipe. The temerature (and thus pressure) in the exhaust system goes up, making the engine less efficient and making you use more fuel to go the same distance.
Example: You put one on your CPU. Same deal, except your cooling system now has to work harder to keep it at a reasonable temperature, and thus uses more power.
Example: You wear a swatch. It takes a little bit more energy each time you move your arm. If you want to power a computer the same way, you'll soon be too tired to type.
The key point is in every case you will have to put more energy in than you get back out. That's why perpetual motion machines do not and can not work.
-- MarkusQ
Ok, I want to point something out to all those who don't get this:
Using something like this requires a temperature GRADIANT... i.e., you could be in a desert that is 5000 degrees, and could NOT use that temperature (i.e. ambient air energy) to generate energy with a junction like this without some form of lower temperature location.
You must have two areas with a temp. gradiate difference bewtween the two that you can place this device across... in this case, the gradient can be lower (250 degrees) and is more efficient. This gradient comes from the difference in termperature between the exhaust and the surronding air.
It's all based upon the tech of peltier junctions.
Sapping heat from the smokestack contents will probably cause it to not work correctly.
The goal of a smokestack is to get the harmful exhaust away from the ground long enough that it disperses sufficiently before touching down.
This is done with convection. The hot gas in the tall stack creates the draw that powers it and blows the plume up after it leaves the stack, the hot plume continues to lift itself until it bleeds off too much heat, then it starts coming back down, but presumably dispersed enough to not be too noxious.
The smoke stack was designed with a known gas temperature and dispersal requirement and a desire to minimize masonry. If you take away heat from the gas you will reduce your plume altitude and cause it to come down in a more concentrated region.
I doubt you can use the thermo-generated electricty to run blowers to compensate. The `no free lunch' law of thermodynamics will probably forbid that. (Unless blowers are much more efficient than convection.)
Now, if you are just bleeding off waste steam then it would work, but most of the energy in steam is the expansion from water to steam, there is relatively little left in the puffy clouds.
Mostly unrelated note: I used to live in Pittsburg in a community where all the houses were required to have slate roofs, stone or brick exteriors and no wood trim. Even the window frames were metal. It was a fire-proof community from the days when the steel mills spewed lots of solids including hot cinders. The plume was powerful enough to carry those large distances fast enough that they were still hot enough to start a fire.
- (T1 - T2)/T2
where T1 is the temperature at the hot side, and T2 is the temperature at the cold side. Both of these temperatures are measured from absolute zero.This is why extracting energy from something that's just a little warmer than its environment is very inefficient. With the hot side at 100C and the cold side at 20C, you're limited to about 20% efficiency in theory, and will be lucky to get half that. Power plants generate steam at upwards of 600C, not just above the boiling point, for exactly this reason. Gas turbines run even hotter. Solar plants for power production typically focus enough energy on a target to reach the 600C level, as Solar Two in Mojave does.
You just can't extract much power from things that are merely warm. They have to be really hot.
It seems so far that most of this discussion focuses on this technology's application to automotives, which are, obviously, an enormous source of fuel consumption. But what about more fundamental wastes of heat?
Quite nearly every home contains dozens of devices that let off lots of energy while in use. Think of your oven, dryer, toaster, refrigerator, furnace... dare I say woodstove?!? Lining these heat-driven devices with such a product could prove valuable.
Consider the open flame of a gas range literally belching heat, much of which escapes into the air or is absorbed by the metal around it. What if the oven and catch-plates below each burner were lined with a hard-coated version of the device? Maybe in the common home this would prove impractical, but surely in commercial kitchens where ovens and stoves are perpetually fired such an implementation would drastically cut down on the total electricity used.
In older homes where radiators are the norm, this might even provide an economical way to prevent burns from leaning up against those pesky pipes!!!
.
Nice guys don't finish last. In reality, they're abducted halfway through the race.
ASPX annouced a device like this a couple of months ago. Includes pictures. Power output is not too impressive but with all the MEMS work these days maybe 10uW aint so bad.
http://www.adsx.com/images/Generator1.html
But the really interesting part is how this company plans to use it. They want to use it along side their digital angel product. Wireless biomonitoring that never runs out of batteries!
By careful selection of materials, ENECO scientists are creating highly efficient, solid state conversion devices, called "thermal diodes," that will operate from 200 to 450 Celsius -- typical temperatures for waste heat and for concentrated solar radiation.
t ml
The very best commercial solar cells today are about 18-20% efficient. The best (research) cell on record, was 32% efficient. It's really too bad they don't give any more specifics on this semi-conductor based device, because it wouldn't be too hard to figure a rough solar cell efficiency equivalent (based on the area of a concentrating lens or mirror)
Now perhaps a more interesting use of such a device would be to increase the efficiency of fuel cells, which themselves are not so efficient and produce lots of waste heat. In a residential setting, this heat can be used for hot water and during winter months. But in a vehicle, I can't think of much use otherwise. Powering headlights, A/C, etc. would be great. Especially if they were white LED headlights of course.. (-;
For your reading pleasure:
http://www.nrel.gov/hot-stuff/press/5399world.h
http://acre.murdoch.edu.au/refiles/pv/text.html
"All your waste are reduce by us!!"
*groan*
But not long enough to learn how to spell the name of the city, apparently.
An imperfect plan executed violently is far superior to a perfect plan. -- George Patton
I beg to differ. Being an ex-geek, now a car guy, I'd love to use the heat my engine throws off.
;-)
If the heat is being converted to electricity then there will be less heat. Lower heat in the exhaust alone means lower engine temperatures because the exhaust sytem radiates the most heat near the engine at the headers (the part where the exhaust comes off of each cylinder for you non-car types). Since thats where the exhaust is hottest thats where the devices would be mounted. A lower exhaust temperature means a lower overall engine temperature.
Secondly, the big step is going from 1000 degrees down to 250 degrees. Taking that 250 down to 180 or 160 would likely allow these devices to draw heat from the engine itself. Having these devices draw energy would reduce the work a typical liquid cooling system needs to do, allowing it to be reduced in size.
Newer cars and performance cars are replacing belt driven components with ones powered electrically, most notably fans and water/coolant pumps. Elimiating belts allows the engine to put more power to the wheels rather than turning an accesory. The catch is that these devices need more power from the battery and alternator. Alternators are presently limited to about 150-200 amps, enough for a stripped race machine to run its accesories, but not enough for a street driven car with lights, music systems, and long continuous driving. These thermocouples would add more electrical power to the system and use more of the energy produced by the combustion.
The automotive example is a bit advanced for the time, but in todays science community a potential commercial use is the best way to get money for new ideas.
Sorry if that went on too long, or was too automotive for you slashdot geeks.
I thought that name was familiar! Gary Taubes' excellent book on the genesis of "Cold Fusion", Bad Science, gives a thorough and not particularly kind account of Prof. Hagelstein's role in those events.
Could it possibly be that humour is subjective and the person that modded you down didn't find it funny but the person that modded that comment up did?
:-).
Nah, it must be a conspiracy.
Jesus, get over it.
Isn't everyone bored of comments complaining about moderation or suggestion moderation?
Everything that says "mod this up/down" or "why did this get modded up/down?" should get modded into oblivion as a matter of course. (He said breaking his own rule, please mod me down
I've always been struck with how much energy is thrown away in cooling towers at turbine-based electric generating plants.
Just a little background for people who don't understand the function of a cooling tower. A turbine plant turns it's turbines by converting a liquid (typically water) to a gas (steam). Once you have the steam, you have to cool it down if you want to use it again or if you want to efficiently discard it. Some plants are designed to cool it down to the point where very little additional heat will boil it again, but this can be tricky. Some plants have been designed such that the waste steam is cooled in heating buildings through steam radiators, but it can be problematic finding customers for this steam, especially year round.
If we have an efficient way to convert this steam to energy as we cool it, then the efficiency of these plants could go way up.
On a related note, I wish the politicians were seriously working towards about energy efficiency, alternate fuels and new oil exploration now. I only hear half measures and partisan wrangling. It's like the politicians seem to believe that we can't have BOTH more energy efficiency and new energy sources. I'd like to be less dependent on some of the foreign oil now. Some of those areas just aren't looking too stable these days.
The amount of practical power you extract has little if anything to do with theoretical efficiency. The efficiency is based on an arbitrary equation, the power is actual energy per unit time.
For instance, what about a Stirling engine? It has a low "efficiency" according to your definition--but it uses literally any heat source at extremely low temperature differentials. Which engine is more efficient in a practical sense, the one that uses barrel after barrel of precious oil or the one that produces household current from sunshine and snow?
324006
A thermal diode IS a Peltier element. This has been covered in EE Times among other trade journals. All they've done is take the standard BiTe diode, which is very thick, and thinned it down by creating the layers with standard chipmaking techniques. So, instead of one diode junction being about 1mm thick, they make a device that is 0.1mm thick consisting of many tens of layers.
www.eFax.com are spammers
Is there enough heat generated by the generators used in wind generators to allow these to further augment their power output? Seems to me that having these on a wind turbine would be excellent as you have a ready source of air to create a large temp. delta.
Years ago the informatics crowd I hung with was working on the relationship between computation and power.
It turns out that because you need to represent state in a stable mechanism, and you can't change the stable state without using energy that there is a lower bound on the energy required to perform a given calculation.
I have forgetten everything else, and I suspect it is many orders of magnitude smaller than current cpu power usage, but it is enough to break the '==' operator on the parent's title.
Uhhh, just so happens that -40 C equals -40 F.
Coincidence no doubt.
Except the air conditioning cooling system in a car runs directly off the drive system, and not on electricity. The heater runs directly off of heat in the car's cooling system. Consequently, this development really has no impact on vehicle air conditioning or internal environment, with the exception of running a couple relays and a control circuit.
"Alcohol, Tobacco, Firearms, and Explosives" should be a convenience store, not a government agency.
That goes way up if you ditch the radiator, but it's kinda short-lived afterwards.
That depends on the engine. I have an uncle that's worked around some ceramic based diesels that do not have radiators. They are very efficient, but it takes quite a while for them to cool down in order to do any sort of work on them. He's said that it's not uncommon for them to be glowing at the end of the day when they turn off the shop lights.
the good ground has been paved over by suicidal maniacs
(Cynicism follows)
To some extent, the purpose of a smokestack is to get the junk that comes out of it to disperse widely, over lot of people far away who can't do much about it, rather than locally, over the people close enough to it to be able to do something about it politically.
Ahh.. that explains the clown-truck in Maximum Overdrive :)
-Billco, Fnarg.com
A question for someone more knowledgable in physics. Would this technology make it smarter to use gas-turbines in hybrid cars rather than reciprocating engines, since the waste heat is at a much higher temperature?
And could this be used to augment power used with gas turbine generators at hospitals, on ships and oil platforms or even APU's in airplanes?
Ethan
Peter H. invented the first working XRay laser around 1980. This inspired Edwin teller to promote the Star Wars program. Peter is a very smart guy having raced through MIT as student in two years.
How do I know? I am very close to the business.
Scientists restrict study to entire physical universe; creationist
A hybrid vehicle would probably shut down the engine at idle and eliminate that waste-heat stream, so the thermal converter would be more useful as a way to increase the general efficiency level of the powertrain. If you can get an extra 10% off the 40% of the heat which is rejected through the exhaust, that's 4% of your fuel value; added to a 30% engine thermal efficiency, you've gained 13%. That's nothing to sneeze at.
Scientists restrict study to entire physical universe; creationist
In contrast, the only thermoelectric generator I know you can buy is for running a little fan which goes on the top of your wood stove. The efficiency of these things is very low, and they are only used where mechanical simplicity is an overriding requirement (such as the power supplies on deep-space probes, which are heated by radioisotope sources). If MIT has come up with a converter which is efficient enough to be worth carrying on a vehicle to scavenge energy from the exhaust heat, that's better than anything we've got today.
Scientists restrict study to entire physical universe; creationist
Scientists restrict study to entire physical universe; creationist
Scientists restrict study to entire physical universe; creationist
could we use it for nuclear power generation instead of sream and turbines?
the saftey benefits would be huge.
The Kruger Dunning explains most post on
You'd probably have your biggest "win" by coming up with a way to manage the temperature of the gas going into the cat. If you could come up with a thermostat to switch the heat flow from the header pipe to an "upstream" thermoelectric converter such that the system was only "on" when the gas was getting too hot for the cat (and the pipe was insulated when it was cold), and use a "downstream" thermoelectric converter to make use of all the heat coming out of the cat, you'd be making the best of it.
I saw a patent for an idea which might interest you. Someone had the idea of putting a heat exchanger in the exhaust pipe to rapidly heat engine coolant (this would have to be "downstream", of course). When the engine was warm a valve would open and bypass the heat exchanger. The heat exchanger could be somewhat restrictive, which would increase exhaust back-pressure and exhaust-gas temperature with it. This would make the catalytic converter light off faster and reduce pollution. Not bad for people who live in places where it gets cold, huh?
Scientists restrict study to entire physical universe; creationist