Could it be possible to create electricity from heat?

[Eidolon]

Im sure if it was, then the power industries would be all over it. But I was wondering if it could be possible, but not at this time, to produce electrical potential and current directly from heat. Normally, heat is used to heat something to create kinetic energy which is then converted to electrical energy though a generator. But if electricity could be produced directly from heat itself, then the net efficiency increase would be so drastic that energy could be produced practically for free.

In automobiles, a heat to electricity system could replace all engine peripherials and increase efficiency by reducing engine drag caused by the alternators, AC compressor, power steering, smog pumps, turbo/supercharger, and any other components by powering them electrically using heat from the engine. If used on a hybrid or electric car, any wasted energy from the electronics or motor could be recaptured and stored in the battery.

What I am wondering is why can't electricity by produced by heat without a moderating system?

 

[ExeFBM]

Well solar panels essentially do this, using photons. Heat is emitted as photons just as light is, it's just a bit further down the spectrum.

The ability to get electricity from heat is a side problem, next to how to get an efficient energy transfer. Energy is always lost in the transfer. Solar panels have pretty crap efficiency, but any system that could get as much as 90% efficiency would be world changing.

 

[Gunboat Diplomat]

Considering how heat is basically just the kinetic energy of constituent particles, this question doesn't really make any sense...

 

[death]

http://www.sciencedaily.com/releases/2007/06/070603225026.htm
Yes you can.

 

[borrofburi]

Im sure if it was, then the power industries would be all over it. But I was wondering if it could be possible, but not at this time, to produce electrical potential and current directly from heat. Normally, heat is used to heat something to create kinetic energy which is then converted to electrical energy though a generator. But if electricity could be produced directly from heat itself, then the net efficiency increase would be so drastic that energy could be produced practically for free.

I wrote a response, then read your post, and then realized you weren't asking precisely the question I thought you were.... Ah well, anyway, the answer is... complicated. And probably well answered by ExeFBM already. I can't think of any way to convert heat *differences* (for without a difference there is no way to get work/energy/power) directly to electricity, and many others have failed to do so as well, however this does not mean it is not possible.

In automobiles, a heat to electricity system could replace all engine peripherials and increase efficiency by reducing engine drag caused by the alternators, AC compressor, power steering, smog pumps, turbo/supercharger, and any other components by powering them electrically using heat from the engine. If used on a hybrid or electric car, any wasted energy from the electronics or motor could be recaptured and stored in the battery.

You'd want to keep the AC compressor tied to the engine, same with power steering, and turbo/superchargers. Though since the point of turbos and superchargers are to re-use some of the excess energy, including heat energy, from the engine, a system that captures that energy into electrical energy might make them useless. AC compressors are kinetic devices, so converting to electricity and then back into kinetic energy would be pointless (assuming ACs currently run directly from the engine). Power steering is also a kinetic thing; but more importantly one of the general rules to vital car components is to keep them away from electrical systems: you want power steering to directly be causally linked to the engine running, the less intermediaries between the engine running and it working the better (the less that can go wrong and cause it to be disabled) (though electrical systems are improving in the modern age, even with a low rate of failure it's still good design sense). What this would primarily serve to do is to replace the alternator with a (hopefully) more efficient system.

What I am wondering is why can't electricity by produced by heat without a moderating system?

Well let's think about it a bit and see if I can BS my way into an answer: electricity is the movement of electrons; you can go straight from chemical to electrical because chemical reactions naturally move electrons, so if you set them up properly they create moving electrons over significant distance, thus creating electricity; you can do it with kinetic energy via magnetic fields which move electrons; but there does not seem to be any known similar from of interaction between heat and electrons. Though now that I've finished my response, death has posted a link I have yet to read (preliminary reading suggests it's still heat to kinetic energy (motion of air molecules) then to electricity).

 

[Master_Ghost_Knight]

I don't really understand what you mean, we already convert heat into energy with a heat machine. You can not get directly heat into electricity because they are not the same, you would have to convert it.
Of course the process has limited efficiency you will never be able to conver all the heat into usable energy, and the the second law of thermodynamics is to blame for it.
You can hook a heat machin to the engine of your car and collect some extra energy, but it won't be much, and you can't get him all, you will allways have to lose heat no matter what. But that sort of machin will add some extra weight and that means that the car will need more energy to carry that extra weight, and what you could possibly get from using that sort of machin does not pay fro the extra fuel you will need to spend, so in total you are actually losing energy by having such a device.
Whatever revolutonary idea you may think you have about this, I will have to warn you that the actual result is extremely unsatisfactory. There is simply not much you could possibly do about this situation, and there will never be, it is just a fact of reallity.

 

[Eidolon]

So, what if heated molecules were moved though a field utilizing their own magnetic polarity to produce a current? Basically, have a system which would orient the molecules so that their spins are uniform, then pass them through a coil that would produce the electons.

The heat would be used to actually move the molecules through the collector, and some kind of field would be applied to them at the same time so orient the dipoles so that they are in alignment.

Im trying to figure out how to write it out, I have it in my head how it could work but its difficult to explain. Does any of it make sense or am I full of shit?

 

[Squawk]

So, what if heated molecules were moved though a field utilizing their own magnetic polarity to produce a current?

I have no idea what this means. Heated molecules of what? You basically have two forms of heat. Radiated heat, in the form of photons, and heat as in the energy stored in the molecues of a given substance. In both cases you can use that energy by converting it into some other form of energy using a process. The more efficient you can make that process, the better. I don't know what this has to do with magnetism.

 

[Master_Ghost_Knight]

So, what if heated molecules were moved though a field utilizing their own magnetic polarity to produce a current? Basically, have a system which would orient the molecules so that their spins are uniform, then pass them through a coil that would produce the electons.

The heat would be used to actually move the molecules through the collector, and some kind of field would be applied to them at the same time so orient the dipoles so that they are in alignment.

Im trying to figure out how to write it out, I have it in my head how it could work but its difficult to explain. Does any of it make sense or am I full of shit?

Your intention might be good but there is nothing there. I advise you to read about thermodynamics and particularly understand the first and second law, so you can actualy understand why you can't violate those laws. If your system violates those laws (which most likely does) then you most certainly made a mistake.
And I can say that the charged particles will not work, you wouldn't need to create a field, all you needed is to make a conductor loop, have a circuit corrector and a charger. It wouldn't work not only because the termal vibrations are microscopic and because ionized particles aren't exactly solid or stable, but also because of the electromagnetic feedback (if such effect didn't existed you would violate the second law of thermodynamics, if the law doesn't add up it is a good indicator that you left out something essential).

 

[borrofburi]

So, what if heated molecules were moved though a field utilizing their own magnetic polarity to produce a current? Basically, have a system which would orient the molecules so that their spins are uniform, then pass them through a coil that would produce the electons.

The heat would be used to actually move the molecules through the collector, and some kind of field would be applied to them at the same time so orient the dipoles so that they are in alignment.

Well, that's basically how the sonic heat conversion thing works, only without the quantum rationalizations. The problem is that heated molecules are on the macro level effectively random, so anything we do first needs to organize them, hence the sonic heat conversion thing (or a steam engine, etc.).

 

[Netheralian]

Its called the thermoelectric effect and is the reverse effect used in peltier coolers. It's pretty much what all the nuclear powered spacecraft ever sent into space use to generate electricity. It is really old technology and is exactly how thermocouples work.

http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

It is already being discussed to use this effect to replace alternators in cars

http://www.zigwheels.com/News/Thermoelectrics-to-replace-car-alternators/Thermoelectrics12_20090212-1-1

edit: that last link is kind of annoying if you have skype installed as it thinks its a phone number. I had better uninstall that feature...

Edit2 : I seem to be having lots of trouble imbedding links at the moment...

 

[Eidolon]

Its called the thermoelectric effect and is the reverse effect used in peltier coolers. It's pretty much what all the nuclear powered spacecraft ever sent into space use to generate electricity. It is really old technology and is exactly how thermocouples work.

http://en.wikipedia.org/wiki/Radioisotope_thermoelectric_generator

It is already being discussed to use this effect to replace alternators in cars

http://www.zigwheels.com/News/Thermoelectrics-to-replace-car-alternators/Thermoelectrics12_20090212-1-1

edit: that last link is kind of annoying if you have skype installed as it thinks its a phone number. I had better uninstall that feature...

Edit2 : I seem to be having lots of trouble imbedding links at the moment...

Ah! I thought I was forgetting something! I hadn't actually though of thermocouples. We used them in labs when I was majoring in electrical engineering, but their output was on the level of microvolts so they could only really be used for temp sensors, but seeing as putting many of them in series would create high potentials, it becomes useful.

The article said they aren't very efficient with energy transfer, but it seems that the efficiency would be limited by the density of the thermocouples in the system so more thermocouples per unit should yield better energy transfer. The idea I had in mind was to use the coolant to transfer heat from the engine block to the heat to electricity converter, there by recapturing some of the lost thermal energy.

Usually to utilize heat, water has to be heated to the boiling point, which takes alot of energy to do, and in the process alot of the energy is lost before it even makes it to the turbine, but if water can simply be heated to a level in which the converter can max out its efficiency, then power plants can operate using significantly less fuel.

 

[Netheralian]

@ Eidolon

Read the last link I posted (zigwheels). Volkswagen is claiming 600W from their thermoelectric generators. That's not bad and should completely remove any requirement for alternators (and could potentially power an electric turbo - I'm not going to bother to work out how much power that would require so no clue as to the efficiency).

So sufficient use of the generators could have a number of combined effects. - Electrical energy obviously (improved efficiency with no alternator), engine cooling as a product of electrical production and energy conservation (also improved efficiency and weight with no water pumps or water cooling system. Maybe you still need convective cooling but perhaps only air is required), and the excess energy can drive an electrical compressor or something to improve performance/efficiency further that doesn't affect the mechanical efficiency negatively (from the turbine side of the compressor).

Also it would severely reduce the mechanical complexity of the engine...

 

[kf00kaha]

There's also research going on using TEGs (Thermo-Electric Generators) in trucks, with efficiencies of 1 kW or more. The trouble right now is to get high efficiency in the right temperatures and to fit the TEGs onto the round pipes ect. Can't say too much though, since I would violate some agreements, so you just have to trust me on this But it is a part of a project included in my research program.

 

[Netheralian]

There's also research going on using TEGs (Thermo-Electric Generators) in trucks, with efficiencies of 1 kW or more. The trouble right now is to get high efficiency in the right temperatures and to fit the TEGs onto the round pipes ect.

Cool - not surprised really (although 1KW isn't an efficiency!!! Just being pedantic...). I have been thinking about this for years and had been seeing some hints around as soon as I looked. I'm sort of surprised it hasn't been commercially done yet as the basic technology is as old (or I guess older) as thermocouples themselves.

I'm tempted to ask where you work or if you are at university, if you have any industrial partners...

 

[Eidolon]

@ Eidolon

Read the last link I posted (zigwheels). Volkswagen is claiming 600W from their thermoelectric generators. That's not bad and should completely remove any requirement for alternators (and could potentially power an electric turbo - I'm not going to bother to work out how much power that would require so no clue as to the efficiency).

I know, I read both articles. I was just going by what the first one said in that they were mostly inefficient in that thermocouples don't produce a high current, but having enough in series should be able to create a much higher current, and a denser parallel configuration could increase efficiency and provide more current potential.

Also it would severely reduce the mechanical complexity of the engine...

That is what I was getting at before. The idea of removing engine peripherals and driving them electrically with power from the engine heat alone would increase engine efficiency tremendously. Since most of the energy released in an engine goes to heat and not kinetic movement, utilizing the heat to produce usable energy then compensates for the engines inefficiency.

On a side note, I wonder why modern cars still use compressors driven by the engine instead of a compacted independent system like a small window unit inside the dash. Taking the drag of the AC compressor off the engine would increase efficiency quite abit since an electric compressor wouldn't require as much energy to achieve the same effect as the mechanical one does.

 

[Netheralian]

On a side note, I wonder why modern cars still use compressors driven by the engine instead of a compacted independent system like a small window unit inside the dash. Taking the drag of the AC compressor off the engine would increase efficiency quite abit since an electric compressor wouldn't require as much energy to achieve the same effect as the mechanical one does.

Can't find any links, but I'd be surprised if a car AC uses under 500W to run and more likley 1kW... So I would think there is some more work to do to get enough power to make this feasible. I also think it is a great idea though

 

[scalyblue]

Uh..an electric compressor is identical to mechanical compressor aside from the drive being an electric motor.

Aside from that, an automotive AC unit takes about 7-10kw of energy.

Your compacted window system would completely fall apart in the environment of an engine compartment, and it wouldn't cool the passenger compartment very efficiently even if it didn't.

If the engine compartment stops being a very hot, vibrationy box then that might be subverted someday, but not in any modern car with an IC engine.

 

[kf00kaha]

Cool - not surprised really (although 1KW isn't an efficiency!!! Just being pedantic...). I have been thinking about this for years and had been seeing some hints around as soon as I looked. I'm sort of surprised it hasn't been commercially done yet as the basic technology is as old (or I guess older) as thermocouples themselves.

The trouble with the TEGs is so far that the scientists haven't found materials that have a high enough ZT (a measure of how good the thermo-electric material is) in the right temperature interval. Another problem is how to shape them (as I mentioned before). A third at least has been the cost of the materials, but that may have changed...

I'm tempted to ask where you work or if you are at university, if you have any industrial partners...

I'm a last year PhD student at Chalmers University of Technology (dissertation is hopefully in October next year) working with NOx abatement in the E4 MISTRA program (I know, the homepage is awfully out of date... ), but I have some colleagues working with the TEGs. And, yeah, there are some industrial partners in on this also as you can see by the homepage...

 

[Netheralian]

@kf00kaha - Thanks. I'll check it out...