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A car that runs on hydrogen

  1. Sep 12, 2006 #1
    I have been trying to figure out how much hydrogen it would take to run a car. I am having a lot of problems finding the right equations and such and was hoping someone could help me out. Here are the things I am wanting to know:

    1. How much energy or force does it take to move a piston up and down. I know that force=(mass*volume)/time but I am not sure how to use it and have it make sense?

    2. How do I messure how much energy is being put out when gas is burned to cause a little explosion to move the piston of the engine?

    3. How would I make hydrogen equal to the numbers gas puts out? What numbers do I need for hydrogen and gas to make all of this work?

    4. How do I collect the hydrogen when I use electrolysis? The contraptions I am using don't seem to work.

    5. And last but not least, How much gas is shot into a piston. I know it is just sprayed so it souldn't be to much.

    I really appreciate any help anyone can give me. I am sorry if I posted this in the wrong place. I do think it is possible that a car can run on hydrogen efficiently and for a better price than gas. I am not sure if what I am doing is going to work but at least I have gained knowledge from thinking about this so much. Somebody is eventually going to make a car that is used by everyone that doesn't run on gas. Thank you again for your help.

    Ben Hall
  2. jcsd
  3. Sep 12, 2006 #2
    Right off the bat I'd have to say the tough thing to overcome is getting enough hydrogen into the car. Sure it is abundant, but in it's gas form I don't think you can carry enough to make the car practical. In it's liquid form it would be great but would have to remain cooled to more than -400deg F to remain a liquid. Until you can work out these details you are out of gas...:cry:
  4. Sep 12, 2006 #3
    PS. I see in step 4 you are attempting to collect H gas. You need to be really careful. This stuff is odorless and invisible and highly flammable. You can get into trouble fast. People have even reported explosions from charging car batteries in areas with poor ventilation, due to the hydrogen given off.
  5. Sep 12, 2006 #4
    Search for a paper by crabtree. It's about a Hydrogen economy and has all kinds of information. It might be a publication out of Argonne.
  6. Sep 12, 2006 #5


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    Lower calorific value of petrol/gasoline: 60,970 kJ/l
    Higher calorific value of petrol/gasoline: 65,270 kJ/l

    Lower calorific value of hydrogen gas: 10.00 kJ/l
    Higher calorific value of hydrogen gas: 11.85kJ/l

    It can be done, and they have been made, but the volume specific energy density of petrol and Diesel is so phenomenal that they're very hard to beat. Hydrogen can be stored under pressure, but to attain volumes which would make automotive use viable requires extreme compression, with the resultant added weight of tanks strong enough, and energy consumption for the compressor itself. Cryogenics can also be used to liquefy the gas, but again, energy is required for refrigeration, and the tanks need to be very well insulated (ie bulky).

    Even when liquefied, the energy density of hydrogen is only around a quarter that of petrol/gasoline.

    Ammonia can be used to store hydrogen which is released when required by means of a catalyst. With a relatively small amount of compression and refrigeration the energy density can become reasonably high, but ammonia requires a lot of energy for production, and is a pretty noxious substance; you wouldn't want it on your garage forecourt. Incidentally, these are the same reasons why ammonia is not the favoured catalyst for selective catalytic reduction for Diesel emission controls.

    Metal hydrides can also be used to store hydrogen, and currently this seems to be the industry favoured route for automotive use, with a tank requiring "only" three times the volume and four times the weight of a petrol tank holding the same amount of energy. However, safety issues restrict the type of hydride used to a few levels.

    The thing to bear in mind with hydrogen is that it's not a source of energy, merely a means of storing this energy.

    If you want an efficient, practical, economical vehicle that performs well and is better for the environment than petrol/gasoline, then buy a modern Diesel.
    Last edited: Sep 12, 2006
  7. Sep 12, 2006 #6
    You can also investigate Hydrogen fuel cells. This is what car companies are working on now. Instead of burning the H, like a regular combustion engine, you can make a fuel cell which would create current through an electro-chemical reaction with the hydrogen. The byproduct is H20, which is a welcome emission these days.
  8. Sep 12, 2006 #7


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    However, it should be noted that regardless of what the end-use of the hydrogen is, half of the power to make it comes from coal (unless some special provisions are taken), so water is not the only emission to consider.
    Last edited: Sep 12, 2006
  9. Sep 13, 2006 #8


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    Hydrogen seems to be long way off from becoming an economical and environmentally friendly fuel source for cars. Ethanol and biodiesel make a lot more sense in the foreseeable future.
  10. Sep 13, 2006 #9


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  11. Sep 16, 2006 #10
    A primary benefit of using pure hydrogen as a power source would be that it uses oxygen from the air to produce water vapor as exhaust. Another benefit is that, theoretically, the source of pollution created today by burning fossil fuels could be moved to centralized power plants, where the byproducts of burning fossil fuels can be better controlled. Hydrogen could also be produced from renewable energy sources with no net increase in carbon dioxide emissions. However, as explained below, the technical challenges required to realize this benefit may not be solved for many decades.
    The main challenges in using hydrogen in cars are the very high costs and the low energy efficiencies; so far, there is not much likelihood of overcoming these challenges. Consequently, only a few demonstration vehicles have been made at high cost.
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