1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Heating water with a wind turbine

  1. Oct 11, 2015 #1
    I know there is a similar topic but it has been closed.
    It is about a wind turbine that generates wild AC from 0 to 240V(open voltage) for a maximum of 1500W. Instead of using a charge controller, a battery bank and an inverter I would like to connect a water heating element directly to the wind turbine and collect the heat into a water tank. My understanding is that if I put a 240V/ high wattage element then the turbine will be stalled and I would collect nothing until strong winds kick in. If I choose a 12V/low wattage element it will burn in strong winds. So I would like to use 20 elements of 12V low wattage that will be gradually connected in series by a device. My question is: is there any device that could do that? Connect the first element for an output of 0-15V, then connect the second element if voltage is between 15-30V, and so on untill in very strong winds it will connect the 20th element?
  2. jcsd
  3. Oct 11, 2015 #2
    It sounds unnecessarily complicated if all you want to do is collect some wind energy as electricity in order to heat water.
    All you need is to figure out what sort of power rating is appropriate for the heating element, - probably something like an electric kettle element.
    Then acquire a generator to match it, which would produce a maximum power output below that which could damage the heating element.
    (You could go further and add additional safety features like a fuse or a circuit breaker or even a transistor based current limiter if overpowering is still thought to be possible)
    If the wind is low it will simply produce less electricity and so therefore less heat, but there will still be some amount of heat, although there will be a limit below which the amount of heating is of no real use.
    Last edited: Oct 11, 2015
  4. Oct 11, 2015 #3
    This is probably incorrect. Your 1500W, 240V heating element has a resistance of 2402/1500=38.4 ohms. At lower voltages, it will simply produce lower wattages, e.g., 590W at 150V and 65W at 50V. However, if it's the turbine suppler telling you this, you might talk to another supplier.
  5. Oct 11, 2015 #4
    Well then it makes it all easy and I only have to buy 1 big element. It was just my assumption that the turbine will be stalled because I made some tests with my generator and small load made it easier for the generator to spin, and the more load I was adding the harder it was to spin it
  6. Oct 11, 2015 #5
    You *could* use multiple smaller heating elements along with a fairly elaborate switching system to turn individual elements on and off depending on the present output of the generator.
    However I very much doubt this would noticeably improve overall efficiency and you would also need to be supplying power to the switching gear and related circuitry.
    (In addition there are more potential parts that can fail eventually if you go that route)
  7. Oct 11, 2015 #6
    Thank you guys for the answers.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook