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Water Power, in a Slightly Different Sense

  1. Jan 5, 2014 #1
    In terms of chronological status, it has been months since I have posted here, and I am now an eleventh grader (with another Physics-based interest).

    As of now, there are multiple technologies in existence that could possibly be used to run vehicles in the near future: hybrid systems, bio-fuels (ethanol), fully-electric cars (such as the Tesla), hydrogen fuel cells, etc. What I have been pondering about is whether or not it is possible to run a mechanical engine on controlled explosions caused by the reaction between Hydrogen and Oxygen (creating H20 as a result; electrolysis separates the H2O into usable fuel). This uses both Chemistry and Mechanical Engineering, so I don't know if I posted this in the correct forum; sorry if this question needs to be moved. Do you think this water-engine is possible? Give your opinion(of course, with some reasoning).
     
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  3. Jan 5, 2014 #2

    russ_watters

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    An internal combustion engine (normal car or truck engine) can be said to be "little explosions": you can use most any fuel in that type of engine, including hydrogen.

    ...but I hope you aren't thinking that you can recycle the water into hydrogen and oxygen in the car while it is running, from the energy produced in the car.
     
  4. Jan 5, 2014 #3
    Is it possible to run an engine off the combustion of hydrogen? Yes.

    Using what method it seems like you're propsing? No. I'd agree with russ_waters. It look like you're going in the direction of what sounds to be a perpetual motion machine.

    Could you separate water molecule into their constituent atoms? Yes. But it's going to take more energy than you'd create with that engine, even if you weren't moving anything.
     
  5. Jan 5, 2014 #4

    etudiant

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    You are combining two tasks.
    The easy one is using H2 to fuel an engine, that is pretty well established, BMW had a 12 cylinder demonstrator model about a decade ago. The O2 of course comes from the ambient air.
    The hard one is getting the H2 back out of the H2O that gets formed from the H2 combustion. We have lots of ways to do that, all take substantial energy and expensive equipment.
    In fairness, the analog with fossil fuels would be to regenerate the gasoline from the CO2 and water vapor produced by the internal combustion engine, also an expensive and energy intensive task.
    So you need to focus your priorities, fuel regeneration or hydrogen engine, because either poses more than enough challenges for a study year.
     
  6. Jan 6, 2014 #5

    Baluncore

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    Use sunlight and solar panels to hydrolysis local water into oxygen and hydrogen.
    Use solar electrical power to compress the H2 fuel into a storage cylinder.
    Sell, or release the oxygen, (which is heavy), to the atmosphere so you don't have to cart it around.
    When driving, use the stored H2 and oxygen from the atmosphere to run your spark ignition engine.
    That is a closed system. The only emission is heat and a dribble of drinkable water.
     
  7. Jan 6, 2014 #6

    russ_watters

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    Other than as a "Hey, look at how green I am!" demonstration, that will probably never happen because solar is very poorly suited for that task. Solar peaks in the day when power is expensive and the grid is heavily stressed. This sort of application would best be suited for nigt-time nuclear power, which is essentially free.
     
  8. Jan 6, 2014 #7

    rcgldr

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    I was under the impression that the current "cheapest" source of hydrogen is from crude oil refineries during the seperation process.
     
  9. Jan 6, 2014 #8

    Baluncore

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    I minimised the system complexity by hypothesising a closed cycle hydrogen engine economy in line with the OP's frame of reference. Science is reductionist, we need to minimise the confounding complexity in order to analyse and understand reallity. By considering the minimum closed system, it is possible to do an economic and thermodynamic analysis of the entire cycle.

    The extraction of hydrogen fuel from hydrocarbon fossil fuels is not a simple closed economically analysable system. There is no need for the intractable economic concept of “nuclear power being free at night”. Compressed H2 fuel can be generated and stored during the day by off-grid solar systems.

    Present short term domestic economics do not dictate practicalities in 100 years, or on a planet such as Mars.

    I really don't think turning this forum into a political debate about the hidden economic costs of nuclear energy such as Fukushima is wise.
     
  10. Jan 6, 2014 #9

    russ_watters

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    No, you definitely should not.

    Here's some information on the phenomena, which sometimes results in negative pricing:
    http://cleantechnica.com/2012/12/29...ugh-thursday-due-to-strong-wind-power-supply/

    It also applies to hydro power and surprisingly happened recently for wind power in Europe (they had strong winds and mild temperatures at night).
     
    Last edited: Jan 6, 2014
  11. Jan 6, 2014 #10

    Baluncore

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    The negative energy pricing simply indicates over production of renewable energy and the need for a bigger sink. Any grid needs to be able to manage it's energy flows. A wind generator should feather it's production in an overvoltage situation. Likewise solar inverters on the grid should reduce output current during periods of higher voltage. Where such excess energy is available there should be an industry able to utilise all available “free” energy. There are hydro plants that pump water back up hill as energy storage for use at times of peak demand later. I guess market forces take time to get industry on grid.


    The Japanese car industry penetrated the Western World by running an extra night shift. Since all the depreciation, tooling and labour on-costs in Japan were assigned to the day shift, as production for the Japanese market. It put up the cost of cars to the Japanese people and distorted the market. Selling the night built vehicles at half price in the West could not be classed as price dumping by the West because of the clever accounting involved.

    US farmers are now subsidised on the farm input side by the US Government. They claim they are not price dumping and export to countries that have no import tariffs. This distortion of the market is paid for by the US taxpayers. They are only doing to others what the Japanese did to them.

    Clever accounting and energy analysis rorts like those cannot be performed on a closed system.


    Your antipathy to a closed and analysable system appears to be based on the fact that the closed system I proposed was both “green” and “sustainable”. In order to economically and energetically analyse a system it needs to be closed, or at the very least have solid bulkheads as boundary conditions.

    "Hey, look at how green I am!" = "Hey, look at how analysable I am!"
    I cannot think of a closed analysable system that is not “green”, can you ?
     
  12. Jan 6, 2014 #11
    For future reference (in how I respond), I will attend to as many questions as possible, depending on which ones receive the most mention. I do not intend to ignore any of you; I will attempt to get to all queries within this month.

    From the looks of it, a lot of people are wondering about how this system will provide enough electrical power to facilitate the chemical reaction needed to provide the hydrogen and oxygen for the engine to run. From recent research, I have a small list of possible solutions that may solve this energy issue:

    Electrical Generators- from information I read on Wikipedia (not the best, but a starting point) sending hydrogen and Oxygen through the "free radical" process of internal combustion could yield useful energy in the form of thermal energy, and can have up to 60% efficiency. Also, this is assuming: "a compression ratio of 10 and specific heat ratio of 1.4", based upon the Otto Thermodynamic cycle. This supports the idea that an electrical generator could possibly provide viable power for electrolysis.

    Part 2- If so, these generators could be placed in strategic positions around the vehicle where they would provide maximum output, and minimal degradation of performance. But, these generators probably won't be the only items providing electricity.

    Piezoelectric Generators- these dielectric materials release electrons under mechanical stress. Keeping this in mind, you could also generate energy from the stresses that act on the chassis of a vehicle while in motion. Once again, this probably won't be the only item providing electricity.

    Electrocatalysts- This would possibly lower the activation energy required to initiate electrolysis.

    Thermoelectrics and Thermionic Cathode Properties- Due to the fact that engines heat up while in operation (along with any metal chassis parts nearby), an electrical current could be produced if the engine block and chassis are made of metals that maximize energy output due to thermal and thermionic reactions between the metals.

    In conclusion, implementation of multiple solutions could make the idea of electrolysis, occurring within the vehicle, possible. But, all of these solutions require the use of materials that may or may not be able to stand the stresses of vehicular operation. There are, most likely, still other options that I have missed...
     
  13. Jan 6, 2014 #12

    russ_watters

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    Sorry, no: Conservation of energy applies, period. A car cannot perpetually power itself. And we do not indulge perpetual motion here. Thread locked.
     
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