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Thread: Alternative fuels (for vehicles)

  1. #1 Alternative fuels (for vehicles) 
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    What fuels do you think will be the future, or look most promising?


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  3. #2  
    Forum Professor Wild Cobra's Avatar
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    Methane fuel cell.

    More energy than Hydrogen fuel cells, and actually working in prototypes.

    CH4(g) + 2O2(g) → CO2(g) + 2H2O(l) + 890 kJ/mol

    2H2 + O2(g) → 2H2O + 286 kJ/mol

    There are also types in use that don't use oxygen:

    Neah Methane Fuel Cell


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    Forum Isotope Bunbury's Avatar
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    Immediate future, gasoline hybrids.

    Slightly longer term diesel hybrids, when ultra-low sulfur diesel becomes the standard. I think ULSD is mandated for 2012 in the US.

    Mid-term, full electric. I don't believe this will take off unless and until CCS is proven and effective. This may never happen and then we have a quandary. You can take the soot, the ash and the sulfur out of coal flue gases, but the CO2 is much harder.

    Very long term, possibly hydrogen fuel cells, but I'm still skeptical about the so-called hydrogen economy.

    Very distant future, we'll be living inside our skulls and won't need to travel. (Just kidding, slightly.)
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  5. #4  
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    I don't understand hydrogen fuel cells. Why make hydrogen more complicated than just exploding hydrogen with air? Like, we don't dismiss gasoline because gasoline fuel cells are silly. Red herring?

    Is compressed hydrogen incompatible with internal combustion?
    A pong by any other name is still a pong. -williampinn
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  6. #5  
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    Quote Originally Posted by Pong
    I don't understand hydrogen fuel cells. Why make hydrogen more complicated than just exploding hydrogen with air? Like, we don't dismiss gasoline because gasoline fuel cells are silly. Red herring?

    Is compressed hydrogen incompatible with internal combustion?
    A fuel cell is more efficient than combustion. The problem with hydrogen it twofold. It's expensive to produce in a pollution free manner, and difficult to store any usable volume. People want cars to go more than 200 miles between fill-ups. Another problem is the membrane. Maybe recently they have overcome the issues, but last I knew, they still hadn't found an inexpensive barrier that was also resilient. It seems that contaminants in the hydrogen and air break them down. Usable life becomes a concern. If I recall, it takes 44 kilo-watt hours of energy to make the equivalent hydrogen to replace one gallon of gasoline. That's like more than $4.00 a gallon equivalent just for the power consumption. It doesn't include profits, maintenance, operational costs, etc. I don't see us ever using hydrogen for a power source except for feel-good applications.

    Methane has more energy than hydrogen, can be pressurized relatively safely for usable volumes, and is plentiful. Still have the lifecycle problems to contend with however of the fuel cell.

    As for burning hydrogen or methane instead of using a fuel cell, it is simpler. However, you have those nasty NOx molecules to contend with when you burn fuels in a nitrogen atmosphere.

    I don't think there are fuel cells that effective use complex hydrocarbon chains. I did some reading on methanol and ethanol fuel cells, but they are not so simple.
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    Forum Isotope Bunbury's Avatar
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    As WC says, fuel cells powering electric motors convert the fuel to kinetic energy far more efficiently than internal combustion engines.

    The problem with methane is that it produces CO2 from millions of dispersed sources (cars) that cannot be collected and sequestered. Production of hydrogen by convetional means (reforming natural gas or coal) also releases CO2 but now it's in a centralized location where there is at least the possibilty of capturing and sequestering it.

    Either type of fuel cell should be less polluting than ICE's simply because the energy conversion in the end user is much more efficient. If the hydrogen can be produced by "green" means then hydrogen wins out. I think it boils down to methane fule cells more convenient since almost everyone has a natural gas supply; hydrogen fuel cells on balance less polluting. However, the jury is still out.
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  8. #7 Re: Alternative fuels (for vehicles) 
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    Quote Originally Posted by brushman
    What fuels do you think will be the future, or look most promising?
    Next 50 years. ...same as today, petroleum based. Increasing hybrids during this time but still mostly petroleum derived energy. 50 years from now....depends on any break throughs in efficiency in energy conversions. More natural gas....more electric fueled by coal-fired generation (especially China, India). More electric fueled by nuclear generation.

    Hydrogen? Depends on practical conversion. So far not promising.
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  9. #8  
    Forum Professor Wild Cobra's Avatar
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    Quote Originally Posted by Bunbury
    The problem with methane is that it produces CO2 from millions of dispersed sources (cars) that cannot be collected and sequestered. Production of hydrogen by convetional means (reforming natural gas or coal) also releases CO2 but now it's in a centralized location where there is at least the possibilty of capturing and sequestering it.
    That fear implies that CO2 is a problem, and I have strong feelings against that idea. I have not seen any empirical evidence that goes beyond causation to show CO2 is a problem. I see plenty of well understood and tested science to show otherwise.

    wiki: Correlation does not imply causation

    Rather than continuing an explaination here, off topic, I will make a new thread for it:

    Geosciences of Global Warming
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  10. #9  
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    Seawater! Just fill the tank with a bucket of sea water and run as today.
    All car and engine manufacturers say that it is impossible to create such an engine, but it is only just around the corner now!
    We will never go empty for fuel ever and it is free of charge for all to use.
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  11. #10  
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    Quote Originally Posted by Wild Cobra
    A fuel cell is more efficient than combustion. The problem with hydrogen it twofold. It's expensive to produce in a pollution free manner, and difficult to store any usable volume. People want cars to go more than 200 miles between fill-ups.
    Many prototype and "concept" cars have been demonstrated that get 200+ miles on internally-stored hydrogen.
    If I recall, it takes 44 kilo-watt hours of energy to make the equivalent hydrogen to replace one gallon of gasoline. That's like more than $4.00 a gallon equivalent just for the power consumption.
    Not really a relevant comparison since fuel cells can be 60+% efficient, while your car's gasoline engine is only something like 20-30% efficient. When you buy gasoline you are really buying 3-4x as much energy as you need to move your car, because most of it's going to end up as waste heat. That's why fuel cell cars are able to go 70+ miles on a kilo of hydrogen, while you would be lucky to get 25 miles on a kilo of gasoline. The efficiency disparity will probably only continue to increase, since fuel cells have been getting steadily more efficient in recent years while internal combustion efficiencies haven't improved in any significant way.
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  12. #11  
    Forum Professor Wild Cobra's Avatar
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    Quote Originally Posted by InsaneDesign
    Seawater! Just fill the tank with a bucket of sea water and run as today.
    All car and engine manufacturers say that it is impossible to create such an engine, but it is only just around the corner now!
    We will never go empty for fuel ever and it is free of charge for all to use.
    OOICU812
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  13. #12  
    Forum Professor Wild Cobra's Avatar
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    Quote Originally Posted by Wild Cobra
    If I recall, it takes 44 kilo-watt hours of energy to make the equivalent hydrogen to replace one gallon of gasoline. That's like more than $4.00 a gallon equivalent just for the power consumption.
    Not really a relevant comparison since fuel cells can be 60+% efficient, while your car's gasoline engine is only something like 20-30% efficient. When you buy gasoline you are really buying 3-4x as much energy as you need to move your car, because most of it's going to end up as waste heat. That's why fuel cell cars are able to go 70+ miles on a kilo of hydrogen, while you would be lucky to get 25 miles on a kilo of gasoline. The efficiency disparity will probably only continue to increase, since fuel cells have been getting steadily more efficient in recent years while internal combustion efficiencies haven't improved in any significant way.[/quote]
    This is true. Fuel cells are about twice as efficient and when you have en electric motor, you can easily have regenerative braking as well.

    There is a highly probable way that hydrogen can be stored safely in a car, I think the dangers are almost fixed:

    Hydride Compressor
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