electric/water powered cars coming yet?

Discussion in 'General Science & Technology' started by science man, May 14, 2010.

Thread Status:
Not open for further replies.
  1. Rogerg Registered Senior Member

    Messages:
    8
    You are absolutely right. I would just like to have his technology spread around a little for that point in time when and if oil price does spike or production gets down to a trickle. If enough people had GreenGas.cc machines and played with them I am sure they would get more economic. Also dont forget about the pollution (GHG) side. If fuels where close to the same price you should pick the one that polutes the least. Apparently Nocera at MIT figured a lower cost way to seperate hydrogen and I believe GreenGas.cc does it also. I have read it and believe it is cobalt in one of the electrodes. While I think of it we were arguing if Global warming existed, one guy said they never saw a possum in Canada till they started moving North about 20 years ago. ( not scientific I know)
     
  2. Google AdSense Guest Advertisement



    to hide all adverts.
  3. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    Why not ask him some simple questions like: At what pressure and temperature does the H2 and N2 combine to see if he is just blowing BS. I.e. check his answer against the unchangable Chemical characteristics of the reaction given in graph below:

    "... In 1909 Fritz Haber established the conditions under which nitrogen, N2(g), and hydrogen, H2(g), would combine using

    medium temperature (~500 C)
    very high pressure (~250 atmospheres, ~25,500kPa)
    a catalyst (a porous iron catalyst prepared by reducing magnetite, Fe3O4).
    Osmium is a much better catalyst for the reaction but is very expensive.

    This process produces an ammonia, NH3(g), yield of approximately 10-20%.

    Here in graph form are the FUNDAMENTAL LAWS for this chemical reaction, which GreenNH3.com can not change:

    Please Register or Log in to view the hidden image!



    "... At 200 C and pressures above 750atm there is an almost 100% conversion of reactants to the ammonia product.
    {When the equilibrium concentrations shown in the graph are finally reached - the reaction is slow at these lower temperatures.}

    Since there are difficulties associated with containing larger amounts of materials at this high pressure, lower pressures of around 200 atm are used industrially.

    By using a pressure of around 200atm and a temperature of about 500 C, the yield of ammonia is 10-20%, while costs and safety concerns in the building and during operation of the plant are minimised ..."

    Quote from: http://www.ausetute.com.au/haberpro.html

    Note also that the reaction is exothermic and also heat is also released when the gas produced NH3(g) is condensed to a liquid for storage. Furthermore, there is a lot of hot H2 & N2 remaining in the reactor that is mixed with the NH3 formed. As that NH# is cooled to the liquid state heat is also removed as the N2 & H2 cools. To have any hope of being as economical as industrial scale production all this heat must be recovered - ideally in a counter flow heat exchanger to pre heat the incoming H2 & N2. Doing this in small "backyard scale" will make the NH3 produced several times more expensive than simply buying it.

    Cease buying the "song and dance" from GreenNH3.com. They are either (1) well intentioned but very ignorant Or (2) a Scam trying to steal money from the well intentioned but very ignorant. And if you know anyone else who has been mislead, get the to read the facts here.
     
    Last edited by a moderator: Oct 20, 2010
  4. Google AdSense Guest Advertisement



    to hide all adverts.
  5. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    To Rogerg:

    I found report on MIT’s Nocera water splitting at: http://web.mit.edu/newsoffice/2008/oxygen-0731.html but it is long on promotion and short on facts; however I can guess what he has achieved. Certainly not any reduction in the minimum energy required to break the H to O bonds in water – that is set by nature at 1.23 eV; however for economically useful production rates m0re than1.23 V must be applied to the electrodes.

    Typically 1.7V is used to increase the current density (Amp/ cm^2). The H2 produced is directly proportional to the total current and that is the product of the current density times the electrode size. (Bigger electrodes are more expensive so the cost minimum is with smaller electrodes and higher current density.) Unfortunately if you want higher current density you must apply more than the minimum 1.23 V and the efficiency drops and energy cost rises as only the 1.23V is doing the separation.

    What Nocera most likely has done is found electrodes that can get the desired current density with less “over-Voltage” applied. I strongly suspect he has somewhat porous electrodes, as this is how the battery developers also achieve higher current densities (when charging that mean a shorter charge time is needed -very important for making electric cars attractive.) One can really consider these porous electrodes to have much greater “micro-area” than their gross area so really they are using larger electrodes and lower current density (on the gross area of the electrode) Effectively they have “squeezed” big electrodes into smaller volume.

    The typical problem with porous electrodes used to achieve great micro-area in small macro-area surface electrode is that they have shorter lives. I.e. all those tiny microscopic sponge holes get filled with the always present contamination molecule compounds. Or crudely put: “they gunk up.” To avoid this fate, in electrolysis, Nocera will, I predict, need to use triply distilled water, etc. and that adds cost.

    Read more here: http://www.hydrogenassociation.org/general/faqs.asp#energyused including:
    “…For 1 mole (2 g) of hydrogen the energy is about 0.0660 kWh/mole. Compressing or liquefying the hydrogen would take additional energy. One company* produces hydrogen through electrolysis at about 7,000psi at an energy usage of about 60kWh/kg H (2)….” I.e. by doing the electrolysis at the high pressure you need, you can avoid the cost of compressors (and the energy they just turn into heat instead of useful work of compression.)

    HOWEVER, again as implied in my last post 82, I strongly doubt that GreenNH3 could produce HN3 on a modest (back yard) scale even if he had unlimited free source of H2 and N2. Ammonia production is a complex industrial process with very dangerous high temperatures and pressures, special catalysis, heat recovery counter-flow heat exchangers, etc. Because it is so dangerous it would not be legally permitted on small scale in your back yard. Just to compress NH3 probably requires many special permits as it is so toxic and irritating with only a tiny leak.

    * PS note IF their electric cost were at the typical residential rate of 10 cents /kWh their cost for one Kg of H2 is $6. Now 909Kg make a ton. So residential (back yard) production without buying high pressure compressors has a cost per ton is about $5,500/ton, or more than 10 times the cost of just buying the NH3 you want (in large volumes) from industrial producers.

    SUMMARY: Having individuals produce their own NH3 is so extremely dangerous (both toxic and pressure vessel explosions) that it is surely illegal and also very unattractive economically as much more costly than just buying it.
     
    Last edited by a moderator: Oct 20, 2010
  6. Google AdSense Guest Advertisement



    to hide all adverts.
  7. jimW Registered Senior Member

    Messages:
    24
    Re alternative energy,,At Cop 15 a company named Hidro displayed sustainablepowerstation.com ,, we thought it had some merit but not sure?. Principle is that the amount of energy used to put a little air into a tank is less than the amount of floatation work that air lifts to the surface. THen on the way back down the air is first released and gravity does some work to go down. I believe it does not take as much energy to float the tank as the float ride up gives out? Maybe someone knows more. I know the rule is energy in equals energy out, but maybe there is an exception ?
     
Thread Status:
Not open for further replies.

Share This Page