Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Solar powered hydrogen car

  1. Nov 24, 2008 #1
    So me and a few friends have a crazy idea for a science fair project. We want to make a small toy car that runs from hydrogen produced by hydrolysis harnessing electrical power from a solar panel and possibly wind turbines on the car. Besides the problem that we are merely high school students and don't have a great engineering background, I have trouble finding this idea even plausible. Could the solar panel really make enough electricity to make enough hydrogen to run the car? Can we cram enough stuff into a model car for this to work? Our science teacher, says that we could make an attempt and if it doesn't work that could simply be the result of the experiment, but i don't want to invest too much time in something that will not work. So what do you guys think? Is this a plausible idea? Could we do this in 3 months? Do we as high school students have sufficient access to the materials and knowledge required to build this? Money isn't a problem as a local hardware store will sponsor us if we present them with a good enough plan.
    Is this possible?
    Last edited: Nov 24, 2008
  2. jcsd
  3. Nov 24, 2008 #2
    Well we all do what we can or find the most interesting. But there is absolutely no point in converting solar energy to hydrogen. Too much energy is lost in the conversion. Instead consider using solar energy directly to charge batteries and to drive electric motors, which is the best choice. Not to mention that the hydrogen car is much more complicated to build without any experience. Also wind turbines might generate a little bit of drag and make the car unnecessarily complex. I would never say that something is impossible, but the hydrogen model might be a bit out of your reach at the moment.
    Last edited by a moderator: Nov 24, 2008
  4. Nov 24, 2008 #3


    User Avatar
    Science Advisor
    Gold Member

    It's theoretically possible, but the problem is that it would probably be significantly less efficient than if you just drove some electric motors from the solar panel directly (but solar cars have been built for science fair projects a million times). How are you planning to harness the hydrogen once you've made it, a fuel cell?

    That cannot work because it would be a prepetual pachine. You would be using wind turbines to capture energy from the car, only to put that energy back into the car minus any losses you have from the process. Basically the turbines would only net a less efficient vehicle.

    While it is in theory possible (as long as the solar panels are big enough), the problem I see is that electrolysis is a relatively inefficient process. If you want the vehicle to be as effcient as possible, you will want to minimize the number of energy conversion steps you are utilizing. Right now you're talking about converting energy in the following steps:

    1) Solar -> Electrical
    2) Electrical -> Stored Hyrdogen
    3) Stored Hydrogen -> Electrical (I assume)
    4) Electrical -> Mechanical

    Note that the first and fourth steps are compatible with each other, so technically 2 and 3 aren't really required. As a proof of concept it is possible though, albeit with significant efficiency losses in steps 2 and 3.

    You teacher is correct in saying that your scientific experiment could fail and still be valid, that's the nature of the scientific method. However I'm not sure that building a vehicle that uses solar energy to perform electrolysis on water which will then be run through a hydrogen fuel cell is necessarily a "scientific experiment," it's more of a combined application of many technologies together.

    The plan overall is plausible (minus the wind turbines) and could work as long as you try to minimize the losses in your system. 3 months isn't very long, you'd better get started!
  5. Nov 24, 2008 #4
    One could, however, use wind turbines to charge batteries while the car was stationary. When moving the turbines should be locked and folded.
  6. Nov 24, 2008 #5


    User Avatar
    Science Advisor
    Homework Helper

    It could be a worthwhile scince fair project just to show how inefficent it is!
    Build two cars, one solar->electric motor, the other solar->electrolsys->internal combustion engine. Compare the numbe rof parts, weight, complexity and the performance.
    The main tricky bit is going to be building a motor for the H2 powered car, you might be able to get a small single piston engine from a model aircraft to work.
    Forget about the wind turbines that's just complicating matters.
  7. Nov 24, 2008 #6


    User Avatar
    Science Advisor
    Homework Helper
    Gold Member

    Hi tycon.
    When you say this, I think what you mean is to put the solar panels or wind turbines on a 'stationary refueling site' as opposed to on the vehicle itself. If you put solar panels on the vehicle, it would be much easier and effective to use the solar power directly to run an electric motor. And as Mech Eng points out, putting wind turbines on the car isn't feasible - unless perhaps your car sits in one spot and allows the turbine to generate hydrogen, then store the turbine inside the vehicle when it's driven. I don't think that's what you really want though.

    So take a look at putting the solar panels or wind turbines at your refueling station to generate hydrogen, then storing that hydrogen in the vehicle. Understanding how fuel cells work and how electrolysis works, for a high school student, I think makes an outstanding science project! For a college level or graduate student, doing applied technology like this might not be a good project only because it is in principal something that can be done and it's really up to industry to make such things economically viable. For a college student, focusing on specific areas of research is more appropriate. For industry, the excersize goes from one of being a learning experience (such as it would be for a high school or college student) to an excersize in making an economically viable system. Right now, industry is doing exactly that. They are 'playing' with ways to make this kind of system economically viable. Note the systems being developed by industry can be thought of as being divided into 2 main areas of research. The first is producing hydrogen from renewable resources (ie: green resources) and the second being the development of vehicle equipment and the infrastructure to support this new technology.

    You might be interested in looking at various car models you get purchase that do exactly what you're suggesting (using solar power for electrolysis and using hydrogen to power a model fuel cell car). Try a few of these links and look for others. Also, look on YouTube for students like yourself who've made these models and powered them using electrolysis.
    http://www.discoverthis.com/fuelcelcaran.html [Broken]
    Last edited by a moderator: May 3, 2017
  8. Nov 24, 2008 #7


    User Avatar
    Science Advisor
    Gold Member

    An interesting thing to do might be to get two model cars, one that is the solar powered fuel cell car and the other being a straight solar-electric car, and power them under a strong incandescent light bulb (say around 150W) to see which one is more efficient given the same power input.
    Last edited by a moderator: May 3, 2017
  9. Nov 24, 2008 #8
    If you are going to do this, I would recommend making it a rocket car.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook