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Homework Help: Energy and efficiency

  1. Oct 29, 2007 #1
    Hi all. I'm new to the forums and am looking forward to contributing. At the moment, i'm having trouble figuring out this chemistry problem i have for homework.

    The United State's gas and oil supplies are shrinking and are now using the electrolysis of water as a source of energy. The source of electricity is from
    photovoltaic (PV) conversion of sunlight in the southwestern
    US. (a) Assume that a flat plate PV system is used, with a solar
    conversion efficiency of 20 percent and a hydrogen
    production efficiency of 100 percent. Assume the average annual
    insolation in the southwest is 270 watts per square meter.
    Calculate the annual electrical energy produced in kJ/sq. meter. Calculate
    the weight of hydrogen (kg/sq. meter) produced per year.
    (b) The US consumed 44 EJ of petroleum in 2000. How many
    square meters of PV collectors would be needed to supply the equivalent
    amount of energy in hydrogen?
  2. jcsd
  3. Oct 31, 2007 #2


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    What do you think you should do? Where do you start?
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