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Environmental Science

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Environmental Science Solar Energy Lecture Notes Solar Energy is RENEWABLE Renewable vs. Nonrenewable Energy Resources DEMO: Solar Energy can be used 3 ways: Solar ... – PowerPoint PPT presentation

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Title: Environmental Science


1
Environmental Science
  • Solar Energy Lecture Notes

2
Solar Energy is RENEWABLE
  • Renewable vs. Nonrenewable Energy Resources
  • DEMO

3
Solar Energy can be used 3 ways
  • Solar Heating
  • Solar Heating ? Electricity
  • Solar Radiation ? Electricity

4
Solar Hot Water
  • 1890 solar water heaters used in sunny states
    like California, Arizona, and Florida
  • Artificial gas made from coal was available, but
    cost 10X the price we pay for natural gas today
  • 1920 1,000s of solar water heaters had been
    sold. BUT large deposits of oil/natural gas
    were discovered in U. S.
  • Solar water systems were replaced with heaters
    burning these cheaper fossil fuels.

5
Solar collector for heating water
A home in California in 1906
6
  • Today, solar water heaters are making a comeback
    (more than ½ million in California alone!).
  • Heat water for homes/businesses and swimming
    pools (see picture)
  • Panels on roof contain water pipes. Sun hits the
    panels and pipes.
  • Warmed water is then used in a pool

7
Solar Thermal Electricity
  • Solar energy ? electricity
  • Some solar power plants (see picture from Mojave
    Desert) use curved mirror called PARABOLIC TROUGH
    to focus sunlight on a pipe running down center
    of mirror.
  • Mirror focuses sunlight onto the pipe, causing
    the water to boil and produce steam. Steam can
    then be used to turn a turbine to make
    electricity.
  • These rows of solar mirrors arranged in "solar
    thermal power plants. They make electricity for
    more than 350,000 homes.

8
Solar Thermal Electricity
  • PROBLEM Works only when sun is shining. On
    cloudy days/at night, the power plants can't make
    electricity.
  • Some solar plants, use "hybrid" technology?
    During day they use sun. At night/cloudy days
    they burn natural gas to boil water to
    generate electricity.

9
SOLAR THERMAL ELECTRICITY
10
  • Another form of solar power (heat) to make
    electricity
  • (Central Tower Power Plant) ?
  • Sunlight is reflected off 1,800 mirrors
    (HELIOSTATS) circling the tall tower.
  • Fluid (liquid sodium) is heated by sun's rays.
    The fluid is used to boil water ?make steam ?
    turn a turbine and generator
  • This experimental power plant is called Solar II.
    It was built in California's desert.
  • Scientists say larger central tower power plants
    can make electricity for 100,000 to 200,000
    homes.

11
Solar Cells or Photovoltaic Energy
  • Sunlight converted directly to electricity using
    solar cells
  • Solar cells also called photovoltaic cells (PV
    cells) and can be found on many small appliances,
    like calculators, and even on spacecraft
  • First developed in 1950s for U.S. space
    satellites.
  • Made of silicon, special type of melted sand
  • Sunlight strikes solar cells and electrons (red
    circles) are knocked loose. They move toward
    treated front surface (dark blue color). When the
    two surfaces are joined by a wire, a current of
    electricity occurs between negative and positive
    sides.
  • Solar cells ? PV module ? Array.
  • Some arrays are set on special tracking devices
    to follow sunlight all day long.

Photovoltaic Energy Video
12
  • Electrical energy from solar cells can be used
    for lights/appliances
  • Solar energy can be stored in batteries to light
    roadside billboards at night
  • Energy can be stored in a battery for emergency
    roadside telephones where no phone wires are
    around
  • Some experimental cars also use PV cells. They
    convert sunlight directly into energy to power
    electric motors on the car.
  • Solar cells are used in satellites in outer
    space. Here's a picture of solar panels extending
    out from a satellite.

Rooftop PV Modules
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