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Battery + Fuel Cell Hybrid???

Discussion in 'Electric Vehicles' started by ratsbew, Jan 10, 2015.

  1. ratsbew

    ratsbew Member

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    I've been thinking about future cars a lot, and my conclusion is that a battery + fuel cell hybrid car is the way to go. If you have a 100 mile battery and a medium/small sized fuel cell you can do almost all daily driving on battery power and never have to fill up with hydrogen. For road trips you could fill up with hydrogen to maintain highway speeds (which really only requires about 20KW). The battery serves as a high power source for accelerating and climbing mountains along with accepting regen power.

    For most people you would almost never have to go to a hydrogen station. This means hydrogen stations could be far less numerous than current gas stations (more like Supercharger layout...along travel corridors).

    Imagine a Model S with a fuel cell for a moment and what it would be like to own. You could have a smaller, lighter 40kWh battery to reduce cost.

    Thoughts?
     
  2. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    I can imagine additional complexity and cost--not just cost to me but to the general public at large. $2M for each silly state funded hydrogen station comported to $250K for a Supercharger. Then there's the safety aspect. 10,000 psi is scary. And you can't fill at home. And... And... The list goes on.
     
  3. SteveG3

    SteveG3 Active Member

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    ratsbew, I see what you are saying. It may not work, but at an initial glance, your suggestion and it's effect of making the need for hydrogen stations nearly as rare as SuperCharging stations (though not quite) certainly looks like a big improvement over a strictly fuel cell vehicle.

    jerry33, while I'm hopeful Tesla will dramatically reduce SuperCharging time, or find some other means of very substantially reducing recharge/drive time for road trips, right now it takes 40 minutes to fill up a Tesla 80%. if this can be done in 2 or 3 minutes at a hydrogen station, the $2 million to $250K ratio of costs may not be so crazy. not saying ratsbew idea would work, I'm with you re concern about safety, but ratsbew does have an interesting idea in terms of addressing the infrastructure question for hydrogen.
     
  4. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Well, it's not likely to stay 40 minutes (and that seems a very conservative estimate), and as Superchargers get closer together, the time spent at them will be less even at the same rate. There is still the complexity and cost of both car and infrastructure. Toyota just announced that it will be 100 years before hydrogen takes off (and who will be around then to even remember). And it certainly won't be any lighter than the current Model S. It will also have far less room. I just can't see a good side to this.
     
  5. Doug_G

    Doug_G Lead Moderator

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    All fuel cell cars are hybrids, because the power density is too low on fuel cells for acceleration.
     
  6. ratsbew

    ratsbew Member

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    I figured this was true, but how big of a battery do they have? My thought is that the battery should be large enough to only need the fuel cell for long distance travel.
     
  7. Johan

    Johan Took a TSLA bear test. Came back negative.

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    Plug-in HFCVs make a lot of sense, you like plug in hybrids like the Volt, PiP etc. make sense today. The size of the battery though: if it's big, then why have it be a hybrid at all (gas or hydrogen), let it be a BEV in all it's simplistic glory and build out fast charging, right?
     
  8. ratsbew

    ratsbew Member

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    The problem is that "fast charging" isn't very fast.
     
  9. Johan

    Johan Took a TSLA bear test. Came back negative.

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    But it is. Supercharging the first part of a large battery like the 85kWh Model S battery happens at a refill rate of some 300 miles per hour. Gas today is bit, but not that much, faster. Hydrogen may prove to be faster too, we don't know yet. Battery swapping will be faster than any form of chemical refill.
     
  10. ratsbew

    ratsbew Member

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    If a gas pump puts out 5 gallons per minute and your car gets 40 mile per gallon that's 12,000 miles per hour!
     
  11. Johan

    Johan Took a TSLA bear test. Came back negative.

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    Yes it can be impressive. There are also some thing about the fill that takes time no matter what: getting off the road, driving up, plugging in/starting to fill, plug out/hang back nozzle, close lid, drive away. Anyway, my point is there is a certain point on the battery size curve where batteries that big don't make sense to use in a hybrid of any sort. It will change with many variables such as cost, convenience, preference etc.
     
  12. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    And if you are on a trip, there is a 100% chance you are going go do more than just those actions that at the gas pump. Also, for safety reasons, it's a really good idea to take a 30 minute break every 150 miles. EV charging time is probably the one thing that will result in substantially increased road trip safety. (There's a paper in that.)
     
  13. Reykjavik

    Reykjavik Member

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    I don't see a big advantage for a plug in hydrogen hybrid over a plug in gas or diesel hybrid. I think biofuels are more promising than hydrogen, especially at small volume like it would be if 99% of driving is done on electricity from the grid. It is easier to transport the fuel and it is less explosive.
     
  14. derekt75

    derekt75 Member

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    Agreed. I think that a plug in fuel cell vehicle is one of the sillier combinations. The range extender on a plug in vehicle should be inexpensive and convenient. MPGe doesn't matter as much since it's rarely used. Gasoline is perfect for that application, and Hydrogen seems somewhat worst case to me.
     
  15. richkae

    richkae VIN587

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    #15 richkae, Jan 16, 2015
    Last edited: Jan 16, 2015
    You will need vastly more hydrogen stations than superchargers unless the FCHV has a battery as big as the Model S.
    If it is as big as the Model S, why bother having the fuel cell bits? The car will cost twice as much and have a lot less interior room to save a few minutes a handful of times per year. For the cost and the complexity of the fuel cell bits and the H2 storage, you could just have a bigger battery.

    A BEV tops up at home every day, can refill slowly at a ten dollar 120 volt outlet - this is the critical advantage. The hybrid FCHV will deplete its hydrogen a little every time it drives beyond the limits of its battery, and you can only refill it at an H2 station.

    If you have an FCHV with the electric range and chemical fuel range of the Chevy Volt, and the use pattern of the Volt - it would drive about 72% of its miles as an EV. The other 28% of the miles will require H2. You will need H2 stations everywhere with the same coverage as gas stations - many people will need regular top-ups. They will need to be convenient to every neighborhood.

    Since 72% of the miles are not H2 fueled, you could have less H2 station capacity than gas stations.
    Exactly how many H2 stations would you need relative to gas stations? I'm not sure - but filling up with H2 is less than 1/2 the speed of filling with gas.
    Unless there is large over-capacity in H2 refilling - like we have with gas stations - so that no one ever waits, then the advantage over a BEV is lost.
     
  16. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    And at $2M per station, paid for by your tax dollars, it's a very expensive solution to a problem that already has a much better and lower cost solution.
     
  17. ItsNotAboutTheMoney

    ItsNotAboutTheMoney Active Member

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    The problem I think is that even if it worked technically, the economics would be off. The more plug-in you have, the less you use your extender. The less you use your extender, the less you buy fuel. As you reduce extender fuel consumption the less cost and complexity you want to put into the extender. If you have long-EREV you could radically reduce gasoline consumption, potentially by enough that syn and biofuels could replace fossil gasoline and diesel.
     
  18. richkae

    richkae VIN587

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    This report has some projections about H2 filling stations. http://www.nrel.gov/docs/fy13osti/56412.pdf

    The theoretical "early commercial" H2 stations would serve about 70 cars per day for $2.8 million dollars ( estimating it runs at 74% of capacity ).
    The theoretical future large scale H2 station serving about 250 cars per day for a $5 million dollar cost for the station ( estimating it runs at 80% of capacity ).
    An 8 stall supercharger that is 80% full for 12 hours will serve about 150 cars, for a cost of about $150K.
    ( I don't know if the NREL report assumes that that 80% utilization is during daytime hours, or for the full 24, going to assume daylight. )

    So today's supercharger is about 40x more bang for the buck than the "early commercial station", and 20x more than the "future large scale" station.

    But then remember that from above, each Tesla may get about 5% or 10% of its energy from a supercharger, but a hybrid FCHV needs 28%.
    If you call it 10% for the Tesla, then it goes to 112x for the supercharger vs "early commercial" and 56x for the "future large scale" station.

    If the FCHVs aren't hybrids, but get 100% of their energy from the H2 stations, it is 400x and 200x.

    And you haven't even factored in the cost of the fuel.
    That is insanity.
     
  19. VolkerP

    VolkerP EU Model S P-37

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    A large battery in a fuel cell PHEV will serve as a range extender :tongue: between hydrogen fill up stops. People will quickly turn towards the source of energy that is more convenient to obtain. Go figure.
     
  20. Reykjavik

    Reykjavik Member

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    Going to a station is less convenient than plugging in at home. People will use the battery only for most of their driving, especially if the battery range is more than 50 miles or so.
     

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