conservation of energy

Discussion in 'Science and Nature' started by Sunn, Jan 31, 2011.

  1. So recently i've been thinking...why is everyone so worried about how we get our energy? It is a simple fact that energy cannot be created nor destroyed. As such, there is no possible way we could ever deplete any energy whatsoever from the universe. So ideally, we just need to create some sort of 2-part system. Part 1 gathers energy in some way that has the least negative effect on the world. Wind power, for example. Then, create a way so that all biproducts of the electricity produced by the wind power are the same. Say, water for example. Then have another source of power that converts that water back into electricty, and whose biproduct would be wind, thus fueling the first power source again. So you have a cycle which fuels itself.

    Obviously this example isn't really meant to be an actual solution, but just to get the point across. I think it's quite possible to eventually create some kind of system like this. It could have other uses as well. For example, you could create a car that contains some kind of 2-part system like this, and the car would rarely, if not never, need fueling.
     
  2. Sounds like a really complicated perpetual motion machine. Which by the laws of thermodynamics cannot work.

    The generators that run off the wind will convert some of the wind energy to heat. That heat will represent a loss in the system. All the wires that convey they electricity created from the generators will again turn some of the energy into heat. Again losing energy.

    Even if you somehow recover that heat and turn it back into kinetic energy or electricity or something, there will never be a surplus anywhere in the system. And if there is, that surplus which is used (to light your house or run a factory or whatever) will take energy away somewhere else.


    An example of this is like a dam with a hydroelectric plant. The plant will never produce enough electricity to run a pump to pump the water back up into the reservoir above the dam because the generators, the wires, and the electric motor on the pump will consume some of the kinetic energy of the water just creating heat and noise.

    Or distilled to it's most elemental form. If you had an electric motor with a belt on it and the belt runs a generator, the electricity that comes out of the generator will always be less than you fed into the motor because of the heat created by the motor, the generator, the friction in the belt, and the resistance of the wires.


    All you are doing in your idea is adding more steps between the generator and the motor.


    Yes, energy never goes away, it just changed into other forms. But those forms are not always easy or even possible to recover and turn into something useful. Most of it just goes into making the atmosphere a teensy bit warmer or something.

    The best you could ever hope for is to break even.

    And breaking even only means you turn kinetic to electricy in enough quantity to turn that electricity back into the same amount of kinertic to turn back into electric and so on. Breaking even doesn't run your lights or air conditioning or car.

    For that, you need a surplus in the system.



    Our problem with energy right now is that most of what we do relies on coal and oil. Coal and oil are really just batteries. They are stored up surplus solar energy that hit the earth millions of years ago. Plants turned that solar energy into physical mass through photosynthesis. Some plants died and their mass turned into oil. Some of it got eaten by dinosaurs that (indirectly) turned that solar energy into muscle tissue which also has been turned into oil.

    And now a few million years later we are extracting that stored surplus solar energy by burning it.

    But there is a finite amount of energy down there in the ground. And we are burning it up pretty fast. When it runs out (or when it become prohibitively expensive to extract it) we will no longer have that stored surplus energy to draw from and we will only be able to use the energy created by the sun presently - in the form of solar or wind or biofuels.


    That's why nuclear is really the only thing that stands to replace oil and coal. Because it can be a surplus when there is no more buried surplus in the ground. Nuclear doesn't rely on the sun heating up air (creating wind) or growing plants. It's like extracting kinetic energy created in the core of stars billions of years ago.

    We can extract more energy from it than it takes to produce it.


    Or something like that...
     
  3. There's 2 problems with this:
    1) The efficiency of anything we make won't allow us to make the 2-part system your talking about. There is ALWAYS heat loss in a system so anything you can EVER make won't be able to do what your talking about. You can make really efficient systems but the cost of making most systems above say 80% efficiency makes it not worth doing (no one wants to pay a supercar's cost on a car that gets 200 mpg). The reason nature seems to have systems that can last forever is because they usually have a large source of power (or heat in the case of the planet); black holes, the sun (or any star), rotation of the planets core, all huge sources that lose energy from heat.

    2) "It is a simple fact that energy cannot be created nor destroyed. As such, there is no possible way we could ever deplete any energy whatsoever from the universe."

    The problem here is that while it's true that it can't be created or destroyed, it all is trying to become heat to "heat up" the universe. Once it becomes heat there isn't a way to get that energy back in another form. Sure it works at higher temp.'s but think about space, how do you heat something up when the outside temp. is ~4 kelvin above absolute zero? You have to bring in another form of energy AND you will ALWAYS have to feed that system energy to keep it at that temp because it's always losing heat (because the object is also trying to heat up the colder space around it).

    This is why perpetual machines can never be made, at best they could only "draw" power or energy from another universe so it would look like one in this one but in the other universe it would look like an energy "hole".

    Edit: Just saw the other response and they covered it all. The one thing I will say is that nuclear at the moment is the best option but even that one is crappy. It's using the power of atoms but it's basically just a steam engine. Fusion is where the real improvment will come, just once they figure out how to get energy out from the reaction (there are a few projects that are fairly close).

    Just a reminder, Fusion is combining two elements (the sun) and Fission (nuclear reactors) use the decay of an element into several others as it's heat source.
     
  4. Wow very detailed responses...well, i wasn't really talking about perpetual motion. That would be cool, but personally I don't think that's possible. I guess i'm just talking about a really efficient energy system. Even when heat is lost from the reactions and such, if you built some sort of closed system it could still be theoretically possible to recapture that lost energy and put it back into the system. I'm not saying that I know how, but I won't rule out that possibility completely.
     
  5. no system will ever be the ideal closed system. ever.

    the universe has constant energy, yes. this means that the energy lost by any system is moved into the surroundings, and thus the net energy lost by the universe is zero. in the grand scheme of things, conservation of energy is a great ideal.

    however, even the most efficient devices are very inefficient. energy is LOST to the surroundings when generating power. that energy has the possibility of being captured; but usually at a higher energy cost than what can be returned.

    ideally, energy should come from renewable, low cost resources.

    hydrogen. bacteria. chemical reactions.
     
  6. ya... not all energy produced is usable energy, some is converted into thermal energy (heat and sound) which is basically lost into the rest of the universe (so yes your right energy is conserved but its not doing us a whole lot if its dispersed around the universe is it?)
     
  7. Our only option is to go nuclear. Contrary to popular belief, nuclear energy is actually very clean and safe. Unfortunately, we haven't figured out how to harness nuclear fusion for energy yet. Fusion is exponentially more efficient than fission. Fusion is what powers the stars in the sky.
     
  8. nuclear FUSION is clean and safe. however, the efficiency of fusion reactors is not comparable to cost of the reactors and reagents themselves... thus rendering it very cost ineffecient at this stage.
     
  9. Well yeah, why the hell would you ever use fission?

    I don't think cost is the priority at this point. In a few short decades, we won't have a planet anymore unless we switch to fusion.
     
  10. cost IS priority because we have created a world dependent on market economics.
     
  11. Well if the human race plans on surviving much longer, they're going to have to kick that habit.

    Maybe fission could be used, but we'd need a good place to dump all the waste. In my opinion, we could dump it on oceanic crust subduction zones, and just hope it all gets pushed into the center of the Earth. Not very promising, though.
     
  12. I tried making a perpetual motion machine before. I was obsessed with it for the longest time. Then I switched my focus to trying to create things that people use everyday to save energy. Nothing world saving, but if everyone ran, say a water heater or dryer that saves on electric, it'd save overall.

    Once I get some of my smaller ideas running and bring in some money, I have a water heater design I want to build. If it works how I have planned, it'd take only 600W to run as good, if not better than the water heaters with dual 4,500W elements.
     

  13. And pollute the oceans if it doesn't work? I don't understand why people are so bent on using nuclear energy when we can use geothermal, wind, wave, and tide. Those are unlimited energy supplies and are probably MUCH cheaper and safer to convert to energy.
     
  14. What about geothermal energy?

    wrap the heat source such as an engine in a conductive material and theres the energy source. Just need that geothermal energy converter lolz


    in our lifetimes we will see a lot of solar panels. good stock investment
     
  15. because they don't make sense everywhere on the planet. Unless you don't mind running power lines across your whole country. This is also why people saying that the deserts are the best place for solar, they forget that power has to get from way out there to a city.

    There are ways to use the "spent" fuel that your calling pollution as more fuel. Not many do it because it's crazy expensive to make the first element in that whole process. The French I know have more reactors that use the "reusable" versions.

    Yes those sources are "unlimited" but they also aren't as powerful. You can make 1 reactor that puts out more power than 50 or 100 stations of any combination you want to pick. Now you have more land area to put whatever else you want to build and you don't have to build a power station in the middle of a natural spring.
     
  16. Well said. Nuclear energy is the way to go.
     
  17. 100% efficiency doesn't exist :wave:
     
  18. Yes, they are called "Breeder" reactors. Breeder reactor - Wikipedia, the free encyclopedia

    I do not believe nuclear is the best long term solution given current issues like disposal of waste, but it does make sense for now. Despite the fact that the US has not built a reactor in about 30 years (to completion), scientists have still been working on reactor safety. Three Mile Island happened in the 70's and Chernobyl was based on graphite core tech which is similar to the Manhattan Project (World War II). Aside from these two disasters there have been very few incidents in the nuclear field.

    Also consider the large stockpile of Uranium we have in the ground and all the Plutonium we have in ICBM's, warheads, etc., we have enough fuel to power our country for a very long time. We can still pursue solar, wind, geothermal in places that would be appropriate, but the idea of running a power line a thousand miles from the source is not realistic.

    One thing that I am surprised by is the lacking of funding on trying to capture some the the energy released by the nuclear waste. I mean it is pouring out gamma rays, x-rays, neutrons, etc., why can't we make a solar cell for that?

    In the meantime I am going to keep working on my hemp oil diesel idea...grow my own fuel and get stoned in traffic ;)
     
  19. It does exist, we just have not harvested it. The phsyical law 'energy cannot be created or destroyed means that the energy is all 100% there, we are just using 90% of it efficiently and the other 10% is transferred into geothermal or other forms of unused energy that just dissipates. For example, the heat from you car exhaust, it cools down, and all of that thermal energy goes to the atmosphere.



    wow I just typed this out and re-read your post. Im stating the exact same thing as you. I typed it all out so I'm gonna leave it lol. You are completely correct.
     

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