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Direct conversion from heat to electrical energy

  1. Jul 1, 2014 #1
    Hi to all.

    I'm looking for ways heat could be converted directly to electrical energy. I figured out some machinery out there that can convert heat to electricity by difference between temperatures, but this method seems to be inefficient. I just came with an initial idea of how a new machine could be developed, but I even don't have a clue of how this machine could look like.

    Heat means electrons orbiting at high speeds in their atomic orbits right?
    Isn't there a way to extract that energy by magnetic or electric means?

    For example, in a magnet we have orbitals wonderfully aligned in the same direction (right?). Is there a way to extract 'heat' energy of electrons from the magnetic field or something like that?.

    I'm not an expertise on particles behavior, quantic theory and relatic topics, so I would very appreciate any help. Thanks.
  2. jcsd
  3. Jul 1, 2014 #2

    king vitamin

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    Heat is almost never due to electron motion in orbitals (and I say "almost" just because I can't even think of a case where it's relevant, though there may be one). In a gas (like air), most heat is due to the kinetic and rotational motion of the air molecules. In solids at room temp, most of the heat is due to vibrations of the lattice of ions (sound waves) which make up the solid. Heat in liquid is usually due to similar (but more complicated) sound waves.
  4. Jul 1, 2014 #3


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    If a large group of atoms/molecules is vibrating in an "orderly way" it is called sound; when it becomes disorderly it is called heat. Some of this energy will excite the available electronic systems; this will decay after a short time by emission of a photon (quantized electromagnetic radiation) or a phonon (quantized sound).

    So some of the heat escapes as radiation, and the rest just rattles around.

    In metals there are many "free" electrons; these may carry heat via their motion, but they make up an insignificant portion of the total heat of the system.

    Yes; there are a number of ways of harvesting energy from so-called waste heat.

    Temperature difference; here is a recent article:

    and another:

    And another:

    Here is a more general article:
  5. Aug 9, 2014 #4
    Hi to all, in my opinion,

    the better way to capture radiative energy or heat (infrared radiation) and convert it to ordered energy such as electrical energy, could be a novel device that NASA researchers built near 2010. It's composed of 'nanoantennas' arrays, and they could convert radiation (dispersed energy) into electrical energy (ordered energy). The problem now that NASA team is facing with this initiative is the conversion from high frequency electricity to commercial type of electricity.

    Here is a link: http://goodnews.ws/blog/2011/01/30/flexible-nanoantenna-arrays-capture-abundant-solar-energy/

    But above solving an engineering problem, I have curiosity about the working of the universe with the current understanding. I refer very specifically to laws of thermodynamics and such. A very direct question is: What if all the bodies in the universe were at the same temperature?... Would there be radiation from matter?. If conservation of energy and laws of thermodynamics holds true, there should be a temperature difference between objects to exist radiation, right?
  6. Aug 10, 2014 #5
    Could anyone answer to questions I made in the last paragraph?
  7. Aug 10, 2014 #6


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    A temperature difference is not required for radiation to exist. The only requirement is that the objects be above absolute zero.
  8. Aug 11, 2014 #7
    I think is all about advances in science that this kind of things had been overlooked. It's about the "solve the problem" agenda over scientists too. Probably money is involved too?
    Energy could appear from far faaaar away and we wouldn't know nothing about it's origin. If NASA technology is for real, It could be used to make electricity from a lot of kind of radiation that hits planet earth every day.
  9. Aug 11, 2014 #8


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    We have been doing this for a long time, Hydro, PV and wind power all harvest the suns radiation in various ways.

    I would guess the NASA tech. will not be employed on a large scale as the Watt/$ is prohibitively high. ("nano" generally translates to "ridiculously expensive")
  10. Aug 11, 2014 #9


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    Well, except for the fact that the amount of radiation hitting the Earth that originates from outside the solar system is minuscule. The overwhelming majority (99.9% or more) of radiation that hits the Earth originates from the Sun, and we already use several different methods to harness that. Solar panels is one method that comes to mind.
  11. Aug 11, 2014 #10
    The problem is that using technology like hydro or wind could affect global climate and life on this planet. Put simply... using hydroelectricity makes water flow slow, and so is with wind. That could lead to a disequilibrium of the complex system here in this planet.

    Well, this post is also about entropy. It's about disorder and the point of view that energy is going to kill us when the planet reach certain temperature by its nature. Finally is all about heat, and the laws of thermodynamics. Heat could go through radiation without a destination right?. And more about.. matter itself try to disipate heat by itself right? (coloumb forces and/or nuclear forces involved here?). It's the fact that energy should be studied different in these days.
    Last edited: Aug 11, 2014
  12. Aug 11, 2014 #11


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    I think you are stretching the realms of credibility there !!

    of all the ways used to generate power ... hydro, PV and wind would be the least likely to cause damage globally to life on earth

  13. Aug 11, 2014 #12
    I have to quote myself because I want to focus in my last paragraph.
    I really don't know what's going on at the nano scale. I'm not nuclear physicist or alike. My common sense tells me that there should be a temperature difference between two isolated bodies in order to emerge radiation. But also comes to me the picture of atoms disintegration. I mean, if bodies really try to stabilize themselves by wonders of nuclear forces, if they couldn't transfer energy throught radiation, they probably disintegrate in the long term (loss mass or something?). Well, I really don't have any experimental evidence about all of this.
  14. Aug 11, 2014 #13


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    This is utter nonsense.

    <Picture removed by moderator>
    Last edited by a moderator: Aug 11, 2014
  15. Aug 11, 2014 #14
    Hmmmm well, you want an answer to this right?

    Please read newtonian physics before throwing some argument. But more deeply, take a look about what is INERTIA, and what is ACCELERATION, and COLLISIONS. You can see experiments from NASA astronauts in the space, they are very helpful in giving knowledge to people about the real world. The fact is that wind velocity is reduced when it hits a turbine. It transfers it's kinetic energy to the machine. Wind and/or Water velocities affect the whole climate. We as humans have changed global climate. There are advantages and disadvantages about geoengineering, or in more simple words, changing natural course. We can turn desert into land, but we also can do the otherwise. By collecting water in super mega big tanks and altering its flow, we also can control the people right?. But above this, weather is changed. Remember the very basic school water cycle. If the course of water is modified, that can produce disturbances in the evaporation into atmosphere.

    Finally I'm more intrigued about the laws of thermodynamics, so I will very appreciate if someone specialized in the field could answer my last questions.
    Last edited by a moderator: Aug 11, 2014
  16. Aug 11, 2014 #15


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    While hydroelectric plants have clear issues with disrupting the local environment, wind power is effectively benign. The amount of wind you would need to harness to appreciably affect the environment is enormous and beyond our capability at the moment.

    Heat is the transfer of energy, it is not a substance in and of itself. Radiation carries away energy from the emitting object and deposits it in the absorbing object. This tends to reduce the temperature of the emitter and increase the temperature of the receiver.

    I don't really know what this means. Matter emits thermal radiation by virtue of being above absolute zero. This process is extremely well understood and governed by well tested laws.

    Your common sense is incorrect. Two objects at the same temperature will emit radiation from themselves and absorb the radiation from the other object. This means that putting any two objects close to one another tends to increase their temperature, as they are absorbing more radiation, and thus energy, than they previously were when they were isolated. (Also, the term is "emit radiation", not "emerge radiation")

    Not really. If the object couldn't emit radiation it would simply stay at its current temperature until it could get rid of its heat through other means, such as conduction. It wouldn't disintegrate or decay.

    Some articles to read:

    Last edited: Aug 11, 2014
  17. Aug 14, 2014 #16
    I want to finish my post by very thanking Prof. Jim Al Khalili series about Physics Science at BBC, they were really helpful to me. I wouldn't forget series like "Order and Disorder", "Story of Electricity", and "The Secret Life of Chaos". Here some links:

    Order and Disorder 1/1:

    Order and Disorder 2/2:

    Story of Electricity 1/3:
    Last edited by a moderator: Sep 25, 2014
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