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Need Help With Pneumatic Battery

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  • #16
    Im not talking about a perpetual motion machine, here folks. And I agree, in part, that I am not the first one to think of this. In fact, the paper I posted by someone who knows much more then me shows not that Im deluding myself, but that I'm onto something. Sure, I will give you that the efficiency is not up to your standards(yet) but if you are talking about a week a year retreat or a day a month offgrid Bnb, efficiency IS NOT AN ISSUE. What is an issue is if It can provide the power necessary for the time necessary.

    All of your thermodynamics excuses are just saying you cant take power and put in in a batter for later use. I've seen models of using concrete blocks lifted 1000ft in the air to store power. Just because the research is putting power into chemicals does not mean that is the most cost effective over time way to do it. It means that is the direction people are being pointed in.

    It still falls into the category of "If people could fly we'd a dun it already"

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    • #17
      BTW my bet it on the concrete block approach over pneumatic The wire to wire on the block approach seems to be pretty attractive.

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      • #18
        Originally posted by happy_hipster View Post

        All of your thermodynamics excuses are just saying you cant take power and put in in a batter for later use. I've seen models of using concrete blocks lifted 1000ft in the air to store power. Just because the research is putting power into chemicals does not mean that is the most cost effective over time way to do it. It means that is the direction people are being pointed in.

        It still falls into the category of "If people could fly we'd a dun it already"
        Suit yourself. Opinions vary, but to call Thermodynamic principles an excuse does little more than put your ignorance on display. But I've called out your ignorance in that area enough.

        As for storing anything, an electrical "battery" (a battery of electrical "cells" that is) stores work, which is defined as moving a force through a distance. These days work is pretty much synonymous with the word energy. You'll be less ignorant if/when you take the time and make the effort you learn the difference between work and power, which is the time rate of doing work (or expending energy).

        If I was to say an electrical battery can't store energy, I'd be denying reality.

        While not necessarily speaking for Peakbagger, what we're saying is that the (potential) energy released by the partial expansion of a gas - while having some advantages - is thermodynamically inefficient compared to other methods of using stored (that is, potential) energy.

        The elevated block example you cite - and similar to a water reservoir BTW - is no more than an example of potential energy storage by virtue of elevation difference in a gravity field. That's what powers my tall case clock.

        Work stored by virtue of such elevation can be quite a bit more efficient than expansion work done by a gas, the expansion of which is a good textbook example - along with friction - of a process which produces a large increase in entropy - an efficiency killer.

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        • #19
          I started on a response with an example of how much energy it would take to compress a qty of air to 3000psi and then how much electricity that would generate using an air motor but decided that Happy Hipster would ignore it anyway.

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          • #20
            Originally posted by Bala View Post
            I started on a response with an example of how much energy it would take to compress a qty of air to 3000psi and then how much electricity that would generate using an air motor but decided that Happy Hipster would ignore it anyway.
            Well if you’ve done the work already, I’d like to know.

            We used to have a portable compressor to charge Scuba Tanks at work. Certainly was not electric and used a gas motor. Another place I’d charge tanks used a gas motor also. I’ve found that when items are run off gas and not electricity, its because they use a lot of power, more than electricity can easily provide (This translates to no longer 120 volt powered, and need to go to 240 at least). I doubt the energy put into charging a 80 cu ft tank to 3000 PSI is anything close to the energy that comes out of it, even if you were to take a hammer and knock the valve off creating a missile.

            I never thought about the energy lost to heating and cooling.

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            • #21
              Originally posted by Bala View Post
              I started on a response with an example of how much energy it would take to compress a qty of air to 3000psi and then how much electricity that would generate using an air motor but decided that Happy Hipster would ignore it anyway.
              How efficient the process you describe would be will depend on, among other things when and how much heat was removed from the air in the tank after compression but before expansion, and the (in)efficiencies of the equipment. That's a Thermodynamics 101 homework problem.

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              • #22
                I just looked for air motors and found one that will provide 1kw. It requires 1750 lpm ( Litres Per minute) of air to do so.

                Looking at a small handyman compressor with a 1kw motor it will make approx 160 lpm, so not even close to driving the 1kw air motor

                The bauer small dive compressor will pump to 3000psi, I have a petrol one but the electric one is listed with a 2kw motor and listed at 3.5 lpm. It takes an hr to fill a scuba tank to 3000psi from empty and that scuba tank full of air would not drive that 1kw air motor for long enough to anything meaningful, if at all.

                You also have a big maintenance factor in making, storing and using compressed air.

                I just dont have the time or need to work out the specifics of what would be needed to make enough air and store it to make electricity when I know its pointless.



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                • #23
                  Originally posted by Bala View Post
                  I just looked for air motors and found one that will provide 1kw. It requires 1750 lpm ( Litres Per minute) of air to do so.

                  Looking at a small handyman compressor with a 1kw motor it will make approx 160 lpm, so not even close to driving the 1kw air motor

                  The bauer small dive compressor will pump to 3000psi, I have a petrol one but the electric one is listed with a 2kw motor and listed at 3.5 lpm. It takes an hr to fill a scuba tank to 3000psi from empty and that scuba tank full of air would not drive that 1kw air motor for long enough to anything meaningful, if at all.

                  You also have a big maintenance factor in making, storing and using compressed air.

                  I just dont have the time or need to work out the specifics of what would be needed to make enough air and store it to make electricity when I know its pointless.


                  All that is a practical Q.E.D. to what I've been saying throughout this thread.

                  With knowledge of Thermodynamics you can prove it to yourself. I prefer the independence to peddler's hype.

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