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anti diesel idea not working.....

Discussion in 'Motoring Related Discussion' started by turbopete, Dec 22, 2017.

  1. Craiglxviii

    Craiglxviii Senior Member

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    Cost. Always cost. Solar panels have a ~20 year return on investment vs. grid ‘leccy as it stands. Storage of H is decidedly non trivial as everything has to be machined to seal to much finer tolerances AND it’s explosive from the 35% H: air saturation point onwards.

    The other issue is that burning H in a car points to an engine other than a piston type, most likely a turbine or fuel cell. Now, fuel cells are an order of magnitude more expensive than IC piston engines so right now, they’re out. Turbines on the other hand are a power of ten more expensive (7-8x per unit power).

    The problem with them is fuel efficiency. They’re horrendous. They work best when being run at continuous high power and just being left there for as long as possible. Cycling of the power only makes the fuel burn worse. So, the best way to take advantage of a turbine in a car is to link it to a generator and that to some form of electric drivetrain. Yes that’s right, a hybrid.

    Hybrids in this case use a battery to act as a grid, soak up the power generated and provide it back to the drivetrain. Exactly what a fuel cell would require.

    So, the argument becomes one of cost. Internal combustion piston engines (with already developed and paid for infrastructure) at known cost versus massive design and cost problems to achieve the same performance. With the enormous infrastructure problems behind it all.

    That’s the problem behind the debate.
     
  2. Craiglxviii

    Craiglxviii Senior Member

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    ;)

    It would indeed be very neat, but just imagine the outcry over “sealed coolant for life” when its liquid sodium!
     
  3. C350Carl

    C350Carl Senior Member

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    Flubber is the way forwards. ;)
     
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  4. LostKiwi

    LostKiwi Senior Member

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    Or a Rotary... (Mazda already have them running...:)
    (Just don't ask about the range before refills...)

    https://en.wikipedia.org/wiki/Mazda_RX-8_Hydrogen_RE
     
  5. Craiglxviii

    Craiglxviii Senior Member

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    100km!!!
    on how much fuel?!? At 350ba... and I’d love to see the cost of the fuel system!
     
  6. LostKiwi

    LostKiwi Senior Member

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    Yep... 110 litres to do 100km (2.4MPG!) on hydrogen vs 61 litres to do 550km (24.5 MPG)
     
  7. Craiglxviii

    Craiglxviii Senior Member

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    Here’s another one for you. 99.99% pure hydrogen needs to reach a ~50% saturation point with air to become explosive. 95% or below purity needs to reach a much lower saturation point. That’s one of the reasons for the loss of the Hindenburg, by the way, Nazi Germany didn’t have the capability to make very pure hydrogen. The leaking cells shouldn’t have caught the way they did (as its design assumed 99.99% purity).

    When petrogas fuels have purity issues we suffer rough running. What happens when hydrogen fuels do the same- explodey engines?!?
     
  8. mikestrivens

    mikestrivens Senior Member

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    It will happen fairly soon, Kim Jong Un is working on it as we write.
     
  9. Craiglxviii

    Craiglxviii Senior Member

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    Nah. He’s a little short of it...
     
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  10. Naraic

    Naraic Moderator

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    Whilst not a universal battery, it does show it to be possible:

     
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  11. Craiglxviii

    Craiglxviii Senior Member

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    The trouble with any universal battery is, it has to physically fit into the volume available in every car that uses it, and with that battery those cars then have to meet their range targets that they are marketed with and the crash targets they’re homologated to. A non- optimal battery will either result in the battery being too small for the car, or the car being too big for the battery in just about every case. Given that it took the computer industry 35 years to agree on the size of USB connectors I can’t see this one being a flyer. It’s just not in anyone’s interests.

    The issue though is the availability of energy at the point which it’s required. Cars don’t need physical batteries changed (and those batteries moved around, plus the enormous warranty & transportation liabilities that would entail. Each battery is a high voltage thermic bomb.), they need installed batteries charged. Either by a massive proliferation of rapid chargers, or massive investment on wireless charging pads (at traffic lights, under every car park bay etc)- that way the investment is capital based and only undertaken once in a generation, not labour based and continual.
     
  12. colin ling

    colin ling Senior Member

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    Looking at wiki etc, and googling btu’s I found afdc.energy.gov
    This site suggests hydrogen has just under half the btu’s of petrol or diesel
    What measure do we need to compare grunt per £1 in real world terms and then MPG ?
    Thanks
     
  13. LostKiwi

    LostKiwi Senior Member

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    Look at the real world figure of the Mazda.
    110 litres to cover 100 litres using hydrogen at 350 bar (2.4mpg) vs petrol at 20-24mpg.
    Energy density is the measure to use as it measures the amount of energy for a specific volume as opposed to a specific mass.
     
  14. dry run

    dry run Senior Member

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    I wonder how much cleaner and more fuel efficient we could make the I.C.E. if we put the money and brainpower currently being expended on alternative power units, towards that task?
     
  15. C350Carl

    C350Carl Senior Member

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    Why do that though? It's nugatory work as ICE won't last forever. We need something that is more eco friendly delivering equal or better performance (both in terms of power and efficiency). At the moment this appears to be Electric power.

    The problem is the old and bold amongst us stifling the initiative of the younger generation. They need to move out of the way and allow the young to develop technologies. After all they are the one that are going to be using it once the old and bold move on.

    There are many many brilliant young minds out in the world. But they are being held back because of dinosaur CEO's, boards and governments aren't willing to give up the gravy train they currently have when it comes to Oil revenue (be it through profit or taxes).

    Put simply, if Governments and business invested more in the future rather than current tech then a decent solution would be found and funded sooner. Making it cheaper for the consumer. Early adopters will always pay more (current cost of a Tesla) but think about the proposed cost of a Tesla 3. As more companies get on with it then the costs will come down. At least the 2040 change will start to shift the focus of companies towards the future. They've got 22yrs to sort it!
     
  16. dry run

    dry run Senior Member

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    That's a very positive view of the future - I hope you're right. However, the youth of today could soon esily become the old and bold of tomorrow. I don't see the likes of Google, Apple, Tesla, et al acting a lot differently than the older established dinosaur corporations, once they have the power. Which reminds me, its time to do my tax return :(
     
  17. Craiglxviii

    Craiglxviii Senior Member

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    Brayton cycle Internal combustion engines have an efficiency governed by the equation: work done/ heat absorbed.

    Work is proportionate to the difference between the starting and ending pressures during the expansion phase, so increasing the starting pressure can increase the work done. This is accomplished by increasing compression ratio.

    An engine suffers losses due to internal friction. Fuel pumps, alternator, all the ancillaries reduce nett efficiency so anything using electricity in the car is a loss contributor. An operating engine also suffers pumping loss, which is the friction of air & gas moving into and out the engine. When stationary this is negligible, but it increases as the square of vehicle speed. At top speed an engine is using around 18% of its total power output to overcome losses due to friction and pumping.

    Finally, the maximum theoretical efficiency of any heat cycle engine is governed by the temperature differential between heat entering the engine and that of the environment at which it dumps its waste heat. One is fixed (combustion temperature of the fuel) and, as we use pressurised water, the coolant temperature is also fixed at around 80 degrees C.

    So regardless of the technology, any heat cycle engine is governed by its operating pressures and temperatures. Those put together give a maximum theoretical limit of efficiency of around 55-60% of energy in: energy to the crankshaft. Typically this puts car engines at the 35-40% efficiency level.

    So, we look to other means to improve road vehicle efficiency. One of those is electricity generated by means other than heat cycle- solar PV, wind, hydro etc. These have much higher generative efficiencies to the point where total system loss to your 3 pin plug is around 30%. So the work is going into how to increase the energy density of batteries to rival petrogas fuels. Figure that out and 1200- mile range leccy cars are easy.
     
  18. LostKiwi

    LostKiwi Senior Member

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    Energy density is indeed part of the key. The other part of the key is replenishment of Energy once depleted.
    Electric motors are highly efficient (in isolation) and typically run between 78-93% efficiency (calculated on the basis of Pout/Pin). If the generation side can be cracked and storage density improved then it really becomes a no brainer and electric cars will be the future.
     
  19. C350Carl

    C350Carl Senior Member

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    Always the optimist me. ;)

    But in all seriousness look at Tesla. Musk was initially ridiculed at first and now look how they’re doing. They’ve stolen a march on everyone when it comes to a decent EV (talking actually in production and not currently being developed).

    If their EV HGV takes off (UPS alone have placed an order for 125 of them) then they will jump way ahead.

    They offered Australia a deal to build the worlds biggest battery (129Mwh) in 100 days or it would be free. That netted Musk and co $50m as they did it in 93.

    You don’t see any oil company saying they’ll give oil away for free if they don’t build a refinery in time.
     
  20. sailorjim

    sailorjim Senior Member

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    The idea of swapping a partly discharged battery for a new one at a dedicated station is the way to go - I believe they used to do this with home batteries for radios etc before home mains supplies were commonplace. (Long before my time, of course, but I seem to remember folk talking about it) It would need to be an automatic system I imagine, and universal to all models.
     

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