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Thread: Energy Conversions

  1. #1 Energy Conversions 
    Forum Masters Degree SuperNatendo's Avatar
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    Seems to me that the way we currently transform different types of energy into electricity are pretty archaic, basic and simple. We can pretty much instantly transform mechanical and kinetic energy into electricity, and after the advent of photo voltaic cells, you can pretty much directly convert light into electricity. These are fine for mechanical, kinetic, and light forms of energy, but collecting energy for use as electricity from other forms are currently less efficient.

    For instance, as far as nuclear and heat... we have to first convert it into mechanical or kinetic energies before we convert it to electricity.

    As far as nuclear, we only use the heat generated to make steam to mechanically turn a turbine.

    As for heat, again, it is used to first boil water, which loses energy, then the steam produced spins a turbine, again losing energy in the process.

    Just seems very inefficient to me, with the exception of photo voltaic cells converting light, we seem to first try to convert to mechanical or kinetic energy before we convert to electricity.


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    If you have a lot of energy to play with, it probably won’t matter much if you “waste” some of it – particularly if you’re generating more energy than you can conveniently store in a short space of time. This is probably the case in the nuclear case, when a massive lot of energy is produced in just one go.


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    Quote Originally Posted by JaneBennet
    If you have a lot of energy to play with, it probably won’t matter much if you “waste” some of it – particularly if you’re generating more energy than you can conveniently store in a short space of time. This is probably the case in the nuclear case, when a massive lot of energy is produced in just one go.
    Yes...but as we are starting to realize, over time, we find ways to use that energy and then we start needing better more efficient ways to convert, store, and utilize that energy.

    There needs to and ought to be a way to directly convert heat into electricity without first converting the heat into yet another form of kinetic energy in the form of steam. I mean, heat pretty much IS mechanical and kinetic by nature, its just that our methods of collecting that energy requires converting water into steam which loses a lot of that energy. If we could directly convert heat without first transferring it through a liquid medium, we would greatly increase energy production and efficiency.

    Just as fuel cells harness much more energy per gram of mass than combustion engines, there are probably much more efficient methods out there for converting heat into electricity that have yet to be discovered.
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    Quote Originally Posted by SuperNatendo
    Just as fuel cells harness much more energy per gram of mass than combustion engines, there are probably much more efficient methods out there for converting heat into electricity that have yet to be discovered.
    No, not without violating the laws of thermodynamics.
    Carnot's theorem is a formal statement of this fact: No engine operating between two heat reservoirs can be more efficient than a Carnot engine operating between the same reservoirs.
    http://en.wikipedia.org/wiki/Carnot_...ot.27s_theorem
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    Thermoelectric coolers use a direct heat difference to electricity method, but they are only 1% efficient.
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  7. #6 Re: Energy Conversions 
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    Quote Originally Posted by SuperNatendo
    Seems to me that the way we currently transform different types of energy into electricity are pretty archaic, basic and simple. We can pretty much instantly transform mechanical and kinetic energy into electricity, and after the advent of photo voltaic cells, you can pretty much directly convert light into electricity. These are fine for mechanical, kinetic, and light forms of energy, but collecting energy for use as electricity from other forms are currently less efficient.

    For instance, as far as nuclear and heat... we have to first convert it into mechanical or kinetic energies before we convert it to electricity.

    As far as nuclear, we only use the heat generated to make steam to mechanically turn a turbine.

    As for heat, again, it is used to first boil water, which loses energy, then the steam produced spins a turbine, again losing energy in the process.

    Just seems very inefficient to me, with the exception of photo voltaic cells converting light, we seem to first try to convert to mechanical or kinetic energy before we convert to electricity.

    How else would you keep the nation poor, ignorant and willing to work in medieval, dangerous conditions, for retards?


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    we seem to first try to convert to mechanical or kinetic energy before we convert to electricity.
    That's the only way when the energy source is a fossil fuel. Engineers are constantly working to improve the conversion efficiency, but, as Harold points out, there is a thermodynamic limit.
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    bunburry, there is much more energy potential inside fossill fuels than we harness by burning it. We just don't KNOW of any better ways yet, doesn't mean they don't exist.
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    Of course you're right. A coal meteorite could produce much more energy than its chemical energy by impacting the Earth, but it would be tricky to harness it.
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    we talk of converting heat energy into elctrical energy..........
    on the contrary we have means enough to use heat energy itself for various domestic purposes....................cooking.............

    And many a times we use electrical energy(possibly converted from thermal power station) to produce heat as in microwave..............
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  12. #11  
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    Quote Originally Posted by anand_kapadia
    And many a times we use electrical energy(possibly converted from thermal power station) to produce heat as in microwave..............
    Note: A microwave oven does not produce heat directly to cook your food. Instead, the microwaves work by exciting the molecules of water contained in food.

    But of course that there are countless appliances that do convert electrical energy directly into heat (electric iron, electric kettle, etc).
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    excuse me
    but what did u say about the microwave oven............
    but the mechanism is the same as electric iron i.e. by supplying electricity to nichrome element..........
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    A microwave oven does not have a nichrome element. It generates microwaves with a magnetron. The mechanism is not the same.
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    Of course it is very easy to convert electricity into heat, but usually the only way we use to convert heat into electricity is by boiling water and producing steam in order to turn a turbine.
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  16. #15  
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    Quote Originally Posted by JaneBennet
    A microwave oven does not have a nichrome element. It generates microwaves with a magnetron. The mechanism is not the same.
    And a question. Since it produces microwaves then is it so that microwaves have heating effect as infrared rays...........
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  17. #16  
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    To answer the above post, microwaves excite the water molecules in the food or beverage, causing friction within the food allowing the temperature to rise.

    Here is what I'm talking about! Harnessing heat energy using new methods, not sure how much more efficient this scheme would be, and safety and environmental concerns definitely need to be studied, but at least it is a new idea!

    http://www.foxnews.com/story/0,2933,372487,00.html

    "The AVE could generate energy from this waste heat because it connects the ground to the upper atmosphere where the temperature gets as low as negative 60 degrees Celsius (80 degrees below zero Fahrenheit). This cold reservoir draws the warm air up fast enough to turn turbines.

    "All you have to do is send the heat up there," Michaud said, and the extra energy from the AVE could increase the output of a power plant by 40 percent."


    Either way, any idea that uses heat that we have in the past just been rejecting since it is not enough heat to feasibly convert to energy using the steam turbine method it is worth considering!
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  18. #17  
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    Engineers are constantly working to improve the conversion efficiency, (of fossil fuel power plants)
    and this AVE that you reference is a good example of that effort:

    "All you have to do is send the heat up there," Michaud said, and the extra energy from the AVE could increase the output of a power plant by 40 percent.
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