Solar Energy

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Solar Energy

• Morgan Shepard

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What is it?

• About 99 of the energy we use for heat comes
  from the sun
• Solar energy travels to the earth at the speed of
  186,000 miles per second (speed of light)
• Solar energy is radiant energy that is produced
  by the sun
• The energy travels to the earth in waves or rays
  (some are light rays, which we can see, and
  others we can not see)
• The hydrogen atoms in the suns core combine to
  form helium and generate energy in a process
  called nuclear fusion
• The suns extremely high pressure and temperature
  causes hydrogen atoms to come apart and their
  nuclei to fuse or combine
• Some matter is lost during nuclear fusion

Nuclear fusion http//www.lancs.ac.uk/ug/hussainw/
fusion.jpg
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Breakdown of the incoming solar
energy http//en.wikipedia.org/wiki/FileBreakdown
_of_the_incoming_solar_energy.svg
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Uses

• About 15 of the suns energy that hits the earth
  is reflected back into space
• Another 30 is used to evaporate water--lifted
  into the atmosphere and produces rainfall
• Solar energy is absorbed by plants, animals, the
  land, and oceans.
• The rest could be used to supply our energy needs

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Solar energy can be converted into other forms of
energy

• Can be converted into electricity
• Solar power plants
• Photovoltaic (solar cells that change sunlight
  directly into electricity)
• Can be converted to thermal (heat) energy
• Heat water (homes, swimming pools and other
  buildings)
• Heat spaces (homes and other buildings

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Concentrated Solar Power

• Use solar power to make energy
• Must be concentrated to produce the high
  temperatures required to generate electricity
• Different types of solar power technologies
• Parabolic troughs use long reflecting troughs
  that focus the sunlight onto a pipe located at
  the focal line (fluid inside the pipe collects
  the energy and transfers it into a heat
  exchanger)
• Power towers Use large field of rotating mirrors
  to track the sun and focus the sunlight onto
  heat-receiving panel on top of a tall tower
• Dish/engine systems Satellite dishes that
  concentrate sunlight rather than signals
• Concentrated Solar Power (CSP) Technologies
  require a continuous amount of sunlight (hot dry
  regions such as deserts)

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Advantages/Disadvantages

• Solar energy is free and its supplies are
  unlimited
• Produces no water/air pollution
• Renewable resource
• Manufacturing the photovoltaic cells consumes
  silicon and produces some waste products
• Large solar thermal farms can hurt desert
  ecosystems
• Large surface of area is needed to collect the
  energy at a useful rate
• Amount of sunlight that reaches the earth is not
  constant
• Depends on location, time of day, time of year,
  and weather conditions