Is using ethanol to distill ethanol overunity?

Discussion in 'Physics' started by strantor, Mar 29, 2012.

  1. strantor

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    Let's say I build an ethanol distiller, that burns ethanol to distill ethanol, which is in turn used to distill more ethanol. Is that overunity? Would I get more ethanol than it takes to distill the ethanol?

    I think it's not overunity, because there is energy entering the loop from an external source. Ultimately, the sun, via photosynthesis, then fermentation, and finally ethanol. But, I'm not 100% sure.
     
  2. KJ6EAD

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    Of course it's not over unity. The corn and sugar (or whatever) are not being produced by the same system that produces the ethanol.
     
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  3. russ_hensel

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    And you can be sure if a device is over unity it does not work.
     
  4. shortbus

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    Do to the number of folks in the world that believe in "over unity", why hasn't some one started to market a line of products using that as a brand name? I can see it now.... Walmart announces the new "Over Unity" battery and light bulb. Soon to come there new line of "Over Unity" emergency generators.:p:D:):eek:

    And taking a page from Loosie, I hereby copy-write this brand name.:rolleyes:
     
  5. strantor

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    I get the vibe that I worded my question in a way that led you guys to think I was making overunity claims.

    I wasn't making the assumption that it was possible to obtain a net gain in ethanol by using ethanol to distill ethanol, and then using that fact as ammunition to say "does this prove overunity is possible?"

    I was asking if it was possible to obtain a net gain in ethanol by using ethanol to distill ethanol, or is this some kind of quack overunity idea?

    I was a little low on sleep when I asked this. for some reason I kept looking at problem as if the process is actually creating the ethanol, and then using it to create more.. I knew that wasn't the case, but couldn't pull my head out of the rut.
     
    Last edited: Mar 30, 2012
  6. Wendy

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    Wood is cheaper. Of course, if you get busted cost no longer matters. The revenuers take their taxes very seriously.
     
  7. russ_hensel

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    Perhaps your question is "how does the energy to distill ethanol compare to that released when the resultant ethanol is burned?" I am quite sure you can distill it with less than the combustion requires in at least reasonable cases. In the best case you can, I think, compute the lowest required energy required by computing the decrease in entropy in the source and products. This is the best you can do, and a poor still could consume almost unlimited energy in the process.

    The fact that we do this for corn to produce a additive for gas would suggest that this energy balance is true, but politics does odd things, and as I understand it the gains in energy, reduced fossil fuel consumption and pollution are rather minor at best.
     
  8. strantor

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    I've made ethanol before in a makeshift still. it took a lot of propane. I barely got any ethanol out of it. I am considering revisiting the ethanol project, and was pondering what fuel to use this time. Propane seemed pretty expensive, so I was thinking electric - I only pay 12c/KWH and I think I could distill with a couple KW. So if I used a big hot plate that would be pretty efficient. But then, what about using the ethanol itself? A car engine is really a massive power plant in a small package when you think about it. An E85 car engine just sips ethanol. If I could replicate the way it works, maybe use an actual car fuel injector to aerosolize the ethanol at rate measurable in drops per minute (imagine hospital IV tube) and force lots of air in with a blower, I could make a pretty darn respectable energy efficient heat source. At first I thought it would be only barely efficient at all, in terms of energy spent vs energy stored in the final product, but the more I think about it, the more optimistic I am.
     
  9. shortbus

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    An internal combustion engine is more efficient do to the compression of the fuel/air mixture. How will you compress the ethanol fuel in your still heater?

    You will have to look at the BTU that it takes to heat the water present in the pot liquor, to the point of the ethanol separation. I think in the long run it still come down to the conservation of energy and thermo dynamics.

    You could get more heat from the heat source (if not electric) by looking at how a water heater or boiler works. The "chimney" for the heat source is also being used to transfer heat into the liquid in those cases. It is not just being used to heat the bottom surface of the vessel.
     
  10. Wendy

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    I've seen people cook pot roast on their engines for long trips. How about a little ethanol distillation instead?
     
  11. loosewire

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    They have a new gimick,you have to pay $ 49.95 up front to get a diagram


    of this gaget,its a ad on druge,where it gets alot of exposer.
     
  12. strantor

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    What is it about the compression that makes it more efficient? I tend to think that the work done to compress the gasses before firing isn't free - any extra energy you get after firing would be subtracted from the energy it to to compress it initially. Unless there's an exponential factor relating the energy released when compressed. I don't know how it works. Do you think it would be more efficient if I burn ethanol in my generator and use the generator to heat the still electrically? That seems less efficient to me because of all the conversions of energy involved.
    good point. I had thought about boiler tubes or installing a heatsink that penetrates the tank, transferring the maximum amount of heat into the liquid. Maybe I would do well to just scrap the air compressor tank I was going to use, and use an old water heater
     
  13. krp8128

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    Correct, you will see an energy loss anytime you convert sources. When you burn the ethanol to run the generator you are losing energy as heat, which is what you wanted in the first pace to run the still.

    As far as the still goes, you have a set BTU requirement to perform the required heating. The still does not care if that heat is gas, electric or other fuel, it still requires "X" BTU to make more ethanol. You need to pick the cheapest/most efficient fuel source available. The still will always use more energy then the content of the newly created ethanol, or else you have just found the golden physics loophole and created a perpetual motion device.

    Of course, if you have all this ethanol lying around already, why make more?
     
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  14. Wendy

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    I've said this before, but in the states this is illegal, though you can get permits if you so wish.
     
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  15. shortbus

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    Do a google search on DIY propane forge burners. Just adding air from a blower, even a hair dryer, gets more heat from the available gas, compared to a stove type blower. Have you ever seen a steam train engine run? Even when burning wood or coal they send a certain amount of the steam exhaust through the fire box to burn the fuel more efficiently. Thats what makes the puff of smoke come out the stack. Any added air to fuel creates better combustion.

    And I didn't mean to generate electric to heat the pot.
     
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  16. strantor

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    Thanks for the reply. I will respond out-of-order:
    That's where my mind was when I asked the question initially, but I think it's incorrect. The process does not create the alcohol, it simply refines it. The alcohol is already in existence, the product of biological processes (photosynthesis, fermentation, etc) suspended in a low energy density solution of water & alcohol (beer, basically). I suspect that if it took more energy to refine ethanol than what you get out of it, it wouldn't be for sale at the pump. That would also make the same true of refining oil to obtain gasoline, as refining oil & distilling ethanol are basically the same process as I understand it. Does it take more energy to refine oil than the energy you can get out of gasoline? I'm not 100% sure, but I'm betting heavily that the answer is no - I doubt we would have built our infrastructure around such an inefficient process, and where would all the surplus energy come from anyway?
    understood. I am several experiments away from determining how many BTU are required and the cheapest & most efficient means of delivering these BTU to the still. I am leaning heavily toward using ethanol though, for my own reasons. I probably will not choose to go electric or gas unless the ethanol proves to be grossly inefficient.
     
  17. strantor

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    understood. I'm still far from any action; I'm just in the research phase. I have filled out the paperwork from the ATF already a couple of years ago when I was distilling, but never filed it, because I never finalized a design on my still. In the ATF's paperwork, you have to disclose the details of your still and it's production capacity. Unfortunately, while designing the still, you don't know if it's going to work or what kind of capacity it's going to have until you fire it up. I don't know about you, but when I'm designing something, it goes through many iterations of metamorphosis before I settle on something final. I'm not going to submit new paperwork that takes >6months to file (last time I checked), and then wait for it to be approved before I fire it up and see if my latest modification worked.
    Ironically, I have looked into DIY propane forge burners in the past when I was forging knives, and already some designs in mind based on that. I never built one, but I went to go look at some for ideas. Have you seen my forging videos?

    I was thinking something along the lines of a very fine mist of ethanol injected into a venturi with compressed air flowing through it, and a circular vent (can't remember what it's really called) around the outside at the end to draw more air into the mix, after it exits the venturi just like a propane gas forge.
     
  18. THE_RB

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    The energy is contained within the sugars and starches in the initial "mash", all carbohydrates and 4 calories per gram of carbs.

    Fermentation converts most but not all of the carbs to alcohols, which have 7 calories per gram, (but there are less grams of alcohol obviously as there is no "overunity").

    Distillation extracts most but not all of the alcohols. Some of those alcohols can be burned to provide heat to contribute to the heat needed for distillation.

    Anyway, all the energy in the final alcohol product was originally in the carbohydrates, and some percentage of that energy will be in the final product. Technically you would get more energy out burning the original "mash" as that one step will have less energy losses...
     
  19. strantor

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    good point. I could probably get even more efficient by taking an additional step backward and just burn my crops. I need a fuels that will run a car engine though.
     
  20. shortbus

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    Your probably going to be farther ahead to have some type of thermostatically control on the still. The problem when I tried this, was keeping the pot at allow enough temperature to vaporise the alcohol and not create steam from the water. The excess water as steam means you have to distill a second or even third time to raise the proof.

    Is ethanol even the best form of alcohol to make for a engine? Methanol is the stuff used for racing. And methanol can be made from waste, plant stems, wood chips and such. No higher expense for corn or wheat that can be sold as food.http://www.consumerenergyreport.com...ol-technical-merits-and-political-favoritism/

    The oil to gasoline is more efficient do the use of catalysts in the production process. And all distillation I think follows any "industrial" process - the bigger the scale the cheaper the individual product.
     
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