Electric cars are a pipe dream

Discussion in 'General Science & Technology' started by Syzygys, May 20, 2010.

  1. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    I consider the floor of a car to be the part you put your feet on, not the area under a seat.

    I agree they are "Nothing at all like { I } have been suggesting."

    I have been suggesting a multitude of small (2 inch OD or less) parallel tubes in the floor / being the floor / or a rectangular cross section "flat tank" filled with some inert atmosphere baked corn cobs or activated charcoal, etc having a huge mico-surface to volume ratio to absorb the fuel gas as a liquid film on the surface.
     
    Last edited by a moderator: Dec 13, 2011
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  3. adoucette Caca Occurs Valued Senior Member

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    As the drawings Trippy and I have provided the industry has built in both a decent size set of conventional CNG composite cylinders (~10 GGE) and a small back up gas tank (~90 mile range), for a total range of ~400 miles, and without sacrificing trunk space, so your argument that there has never been an NG designed car no longer works.

    But putting them as part of the structure in the floor is highly unlikely because these tanks need to be able to be inspected every 3 yrs/36,000 miles, and replaced if needed.

    You don't want to pay a lot for the inspection and you don't want your whole $37,000 vehicle having to be trashed because the integral CNG tank hit a rock. ($37,000 + $6,000 home PHIL unit = $43,000)

    Which is why these tanks are strategically placed in relatively protected installation locations (back by the rear axle), but can also be easily inspected and replaced if necessary.

    http://www.cleanvehicle.org/committee/technical/PDFs/Web-TC-TechBul1-ContainerInspection.pdf

    The ANG tanks are even less likely in passenger cars unless their volume per liter at least doubles over what is presently possible.

    To have the same 10 GGE ANG tank in this car, at current storage densities, would require about 2.5 times the space as those composite tanks, and that would reduce the vehicle's passenger or cargo space quite a bit.
     
    Last edited: Dec 13, 2011
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  5. adoucette Caca Occurs Valued Senior Member

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    CNG vs Gasoline.

    LA gas prices = $3.56 gallon
    LA GGE Natural Gas = $2.75

    Savings = $0.81 per gallon

    It gets 32 MPG equiv mileage.

    Drive it 16,000 miles per year, for 10 years = 160,000 miles and fuel savings = $4,000.

    But it costs $37,000.

    ($43,000 with a home PHIL option).

    The same basic car, the Chevrolet Orlando, but using a Gasoline engine, sold in Canada for ~$21,000 US.

    http://life.nationalpost.com/2011/12/07/road-test-2012-chevrolet-orlando/

    Add in the extra gas cost, and it's still $12,000 cheaper to buy the gasoline version.
     
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  7. Trippy ALEA IACTA EST Staff Member

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    10,890
    :shrugs:
    The floor of the car has non-zero thickness, and extends under the seats.

    That's not indicative of anything other than different models of Zafira.

    For example, here's a 1996 model Toyota Carib:

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    And here's a 1998 model Toyota Carib (this is what I drive, our car is even the same colour as this one):

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    The Ecoflex has been around since at least 2003.

    One is a show-room plate for an unregistered car, the others are road plates for registered cars.

    The one I posted was Ecoflex.
    However, the differences between ecoflex and ecotec has to do with specifics related to the engine, not the car.
    Ecotec engines[/quote] comprise multiple families of engines used by GM, Holden, Opel (and by extension Vauxhall).

    I've seen cutaways of the Opel Zafira that look like Arthurs, the difference is the year of the model. I deliberately chose the most recent model to try and avoid this sort of confusion.

    Note, for example, how closely Arthurs diagram resembles the 2003 Opel Zafira:

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    It may simply be that Arthurs cutaway is from early in the design process.
     
  8. billvon Valued Senior Member

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    21,634
    If that had significant advantages for fuel storage, manufacturers would have done it with gasoline tanks (which are much, much easier to make and much safer to use than pressurized gas tanks) decades ago.
     
  9. HEXiT Registered Member

    Messages:
    37
    i personally think we should switch to hydrogen run engines... we just need a clever clogs to make something that will easily and cheaply extract hydrogen from sea water.
     
  10. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    23,198
    Good question. Probable one thin walled tank does cost less, as it can be made from two stamped halves wedded together.

    A more importantly reason is fact that with a nearly empty tank, made of many small ID tubes, it would be difficult to get all the air out if filling it with an in compressible liquid, like gasoline.- I.e. you could not fully fill the multi-tube tank with gasoline.

    The gasoline fuel pump would make a vacuum and collapse a gasoline tank into scrap metal without some vent. This vent lets air in not gasoline fumes out. You don't dare put even only an air inlet vent in a gas storage tank. When filling a pressure tank with a compressible gas this is no problem - there would not be any vent as you need with a liquid fuel so the pressure steadily increases up to the liquifaction pressure.

    When during filling the gas pressure gets high enough to make some liquid, that reduces the volume of gas in the tank, so you keep adding gas at that constant pressure until there is only liqufied gas in the tank.
     
    Last edited by a moderator: Dec 14, 2011
  11. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    Yes there is lots of hydrogen on Earth - Getting H2 as / for fuel is more expensive than gasoline or sugar cane alcohol, but the main problem is how do you store it in the vehicle. There are several solutions but all add a lot of weight to the car.
     
  12. adoucette Caca Occurs Valued Senior Member

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    7,829
    CNG does NOT become a liquid when you fill a CNG tank to 3,600 psi.

    If you want LNG you cool NG to -162 C and store it at near atmospheric pressure.

    http://en.wikipedia.org/wiki/Liquefied_natural_gas
    http://en.wikipedia.org/wiki/Compressed_natural_gas
     
  13. adoucette Caca Occurs Valued Senior Member

    Messages:
    7,829
    If it had significant advantages for CNG storage manufacturers would have done it.

    They don't.

    Indeed 9" diameter is as small a CNG tank as I've been able to find, because they apparently aren't more economical the smaller you make them.

    I found these bottles (Small Pony bottles for SCUBA, at 3,000 psi, so very similar to CNG storage, but by necessity, much smaller)

    Here is the Cost per Cubic Ft of air stored:

    6 Cu. $15.50
    13 Cu. $8.69
    19 Cu. $6.11
    30 Cu. $4.90
    40 Cu. $4.25
    80 Cu. $2.00 <== std SCUBA tank.

    Which clearly shows why manufacturers go to larger diameters, not smaller, when building tanks for storage of high pressure CNG.

    http://www.amazon.com/dp/B0000E1MDX
     
  14. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

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    23,198
    Thanks for actually quoting me this time, rather than saying I had stated CNG became a liquid at 3600PSI.

    I don't know (have not seen, have not searched for) CNG's pressure vs temp curve for the gas / liquid equilibrium.

    This is why I have NEVER stated any pressure for tanks, whose geometry and efficiency I did discuss, to operated at. When "efficiency" is defined, as I did, by the storage VOLUME to wall volume there is no need to specify any pressure. I did once or twice calculate with 3600psi when you or billvon suggested I consider that pressure.

    Also I note that while in some applications it is true that larger diameter tanks are the most common, in other application they are the exception, especially when very high pressures are used. For example a truck transporting hydrogen or Helium gas will always have many parallel small diameter tubes not one large one. See photos at end.

    Despite your many posts saying large ones are preferred, and telling I was wrong, it is true that the efficiency of a cylindrical pressure tank does NOT depend upon the diameter to first order in the wall thickness, t, to ID, d, ratio (t/d). I.e. as t << d, the higher order term (t/d)^2 is un-important compared to the t/d terms.

    Two H2 transport trucks:

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    Note truck's wheels lower left of the second photo. The truck's tractor does not show. Behind this foreground truck is second truck with four small tube H2 modules and one is sitting on the floor showing end view.
     
    Last edited by a moderator: Dec 14, 2011
  15. adoucette Caca Occurs Valued Senior Member

    Messages:
    7,829
    Except Billy your whole post was wrong.

    CNG isn't a liquid above about -87 C and no current fuel is pumped in as a gas and liquefied within the receiving tank as you erroneously suggested.

    Even Propane, which is used as a liquid, is transfered from the storage tank to the receiving tank as a liquid (they vent the tank as they fill it until liquid emerges).

    Yes, you are wrong Billy.

    As the previous post shows.
    It is much more expensive to use a lot of small tanks to store a given quantity of gas than one larger one.

    And expense is a valid measure of efficiency, since it includes the cost of making the cylinders.

    Of course, as you go up in size eventually you get to a point where the efficiency of manufacturing is overwhelmed by the cost of handling much heavier materials and so at some point, making very large cylinders also becomes less efficient and impractical because it increases your manufacturing costs and increases your handling costs, which is why that in the real world almost all CNG tanks are between 9 and 16" in diameter. Like those pictures of tanks you posted. They look like they are in the ~16" catagory.

    Smaller and your costs goes up per m^3 of gas and over a certain size and your manufacturing/handling costs go up as well.
     
    Last edited: Dec 14, 2011
  16. billvon Valued Senior Member

    Messages:
    21,634
    And is more volumetrically efficient.

    With a vent at the top of each end that would be trivial.

    Are you honestly saying here that you don't think gasoline tanks have vents?

    Here we go again.

    You can't liquefy room temperature natural gas by just adding it to a tank at 3000-4000psi. It won't liquefy. It may well liquefy at some pressure far beyond that, but that's going to require some very exotic tanks and materials - certainly not a bunch of welded together C's.

    Next you're going to post "but I never said I planned to put that particular pressure in my excellent flat tank!" even though that's the tank we're talking about. Whatever.
     
  17. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    Yes, true for holding a liquid, like gasoline at near atmospheric pressure. It is only pressure tanks efficiencies that are independent (to first order) of the diameter because, unlike a low pressure tank, the wall thickness must increase with the pressure of the gas contained. This makes contained volume to wall volume (product of thickness and circumference) ratio a constant, neglecting end effects, which usually very slightly favor the smaller ID tanks.
    It would need to be a very sophisticated valve that allows the air to escape but does not allow the gasoline fumes (and certainly not the gas one is trying to hold in the tank.) to escape. One way values are not very complex, but the discriminating exit valves you speak of/ are suggesting / need to sense and discriminate what is leaving (Gasoline vapors vs air) – Perhaps a small spectrometer as the detector could do this task?
    No, I clearly said they have a simple “one way” valve that lets air into the tank but lets nothing go out. Read again the sentence of my post now bold.

    I guess so as both you and adoucette* don't read with full comprehension what I ACTULLY say. Instead you both often think I said something I did not. This is for example why you asked me the above question even though I clearly not only said the gasoline tank has a valve but even told it was valve that let air in but not gasoline fumes out. ~60 or more years ago when there were less cars and people were not so aware of health damage caused by petro-chemical smog, I think the vents did let gas fumes, as well as air go out.

    Another very common example of assuming something I never said is in next part of your post below. There are quite a few gases that could be stored (several even for use as a fuel) as liquid in pressure tank but you, I think, are assuming the tanks I have discussed (geometry and efficiency only) can only be used to hold gas like CH4. I will not bother to look up the pressure vs. temperature curve for gases that would liquefy at modest pressure but bet heptane and hexane would easily liquefy at modest pressure near room temperature. Again for what is about the 20th, time I have not specified any pressure or any particular gas. Assuming that I have and then being critical of me for your assumption is not fair. MY POSTS ARE ABOUT TANK GEOMETRIES & EFFICIENCIES, NOT SPECIFIC PRESSURES OR SPECIFIC FUELS unless asked to consider some particular pressure and gas as you did when concerned that the tank would explode if it held the 3600 psi which YOU suggested.
    That is true for some gases (like CH4) and false for others (like C7H16, heptane, or some shorter hydrocarbon gases if heptane is already a liquid at room temperature and pressure).
    Yes. I see you have become aware that I am speak of the tank, not what it contains, but I admit the gaseous fuel (not the tank) most discussed in this thread is CH4 with only a few posts pointing out that there is much to be said for butane and some (but not me) think for H2 especially if tank is filled with a highly porous material to surface adsorb it.

    When not forced to reply to / discuss / pressures or specific gases suggested by others, my posts have concerned two novel pressure tank types: One a set of many parallel small ID tubes & and the other many parallel rectangular cross section “tubes,” all but one sharing a common wall, which having no pressure across it does not “bow out.” – These common walls are really a “tension webs” between the two flat sides.

    ---------------
    *For another example in next post 1337, adoucette assumes I must be speaking of fuel tanks, and yes that is one use but not the only use of tanks. Especially as at one point I did not know my multi-chambered, shared wall / tension web / tank was already for sale, I was thinking in term of a patent and trying to be as general as I could be - tanks have many uses other than as fuel tanks. It is really a sad waste of my time that at least half my posts must point out that I never said the thing I am be criticized for. Adoucette's post are usually filled with unstated assumptions. For example that heptane can not be used as fuel as it has zero octane rating. - It works just fine in a Sterling engine - the most efficient engine that exist.
     
    Last edited by a moderator: Dec 15, 2011
  18. adoucette Caca Occurs Valued Senior Member

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    7,829
    Hilarious Billy.

    Heptane is the zero point of the octane rating scale. It is undesirable in petrol, because it burns explosively, causing engine knocking,

    http://en.wikipedia.org/wiki/Heptane

    LOL

    Dance much?

    There is NO automotive fuel that makes sense to use in your 2" OD multiple tube tank.
     
  19. billvon Valued Senior Member

    Messages:
    21,634
    All modern cars have one. Google "onboard refueling vapor recovery."

    Nothing so complex is needed. Activated charcoal works just fine.

    I did, and that sentence is still incorrect. Cars do not have a simple "one way valve" on their gas tank.

    "You can store methane in a cool new tank I thought up!"

    "You can't store methane in a tank like that."

    "I never said it had to be methane. I said . . . . heptane! Yeah, that's the ticket."

    "It can't be heptane, it's a terrible fuel."

    "I never said it was heptane! YOU ARE LYING!"
     
  20. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    If any of this is supposed to be a statement of mine, give link to post where I said that (or even something close to that). It is things like this "putting words in my mouth" that I find both annoying and dishonest.

    I may very well have said: "I never said it was heptane." when replying to someone stating I had said it was heptane, but yes tanks can store heptane, but I don't want to be specific about their use. I want and only do discuss tank geometry and efficiency, not their uses, unless forced to in replies.

    I am certain I would, not even in a reply, say: "You can store methane in a cool new tank I thought up!"
     
  21. adoucette Caca Occurs Valued Senior Member

    Messages:
    7,829
    Billy do you take us for fools?

    YOU started this whole line of argument discussing NG because you claimed a NG car hadn't been designed:

    AND

    AND

    AND

    AND

    (Red highlights added for emphasis)

    So Billy, it's by your own admission that these tanks you were designing were NG Tanks.
    You said it OVER AND OVER AND OVER.

    Your posts were clearly stated as solving the problem of CNG storage in a car designed for CNG.

    Only after you posted that picture of the Propane tank that you claimed validated your design did your story change and you started to distance yourself from CNG.

    Finally to your outright lie in post 2296:

    So yes, your ability to lie and lie and lie again, was caught perfectly by billvon paraphrasing your posts.

    Worst thing Billy is you have lost all credibility over such a trivial issue.

    Arthur
     
  22. billvon Valued Senior Member

    Messages:
    21,634
    You're an amusing guy.
     
  23. Billy T Use Sugar Cane Alcohol car Fuel Valued Senior Member

    Messages:
    23,198
    Yes I certainly, especially in this thread about next generation cars, I do want the novel tanks I have been suggesting to be part of that next generation of cars.

    And yes, thinking about how LNG could be better stored in that next generation is why I "invented" the tanks and began several post of analysis on them, which you refused to understand / review. You should have as it was quickly done and had errors you could have pointed out, but you preferred to basically claim those tanks are not possible ("unobtanium" you called them) and or parroted the common POV that circular cross sections must be best (and they are if only one tank is to be used) even showing photo of air plane cross section and lots of commercial data on cylindrical tanks to "prove" your POV, but nothing relevant to joined multiple parallel cells with shared common walls being the tank.

    Fact that initially I was trying to find better tank for LNG cars does not mean I am limited to that for ever. Better tanks have many uses. - Once I got the idea that many parallel rectangular cross section tanks, sharing common wall, could be more efficient, then my focus was on tanks, not what they contained.

    Unfortuntely I was not the first to think of this idea - later learned they are for sale when I got serious about seeking patent (spending money) and did a more complete search - found the seller of them, who has patents in several countries in addition to the US.
     
    Last edited by a moderator: Dec 16, 2011

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