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PowerPoint Presentation - Geothermal Energy

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					Geothermal Energy
      By: Amalie Vega
     Geothermal Energy in Natural
            Phenomena
When a volcano erupts, it spews hot lava,
                                        QuickTime™ and ath
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 or magma. This magma starts
 underground and heats rainfall that has
 seeped deep into the Earth’s soil.
Sometimes, this water moves back up
 through cracks in the underground rock,
 and comes back up to the surface in the
 form of hot springs or geysers.
Pools of water that collect underground toand athis p
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 are called Geothermal Reservoirs.
Energy Transitions: Where it Starts

If you travel into the Earth, it gets hotter
 and hotter as you get deeper and deeper.
The center of the Earth (the core to all
 those science types) is the hottest…
But about a mile underneath the ground is
 naturally hotter than above.
The kinetic energy is high- and ready to
 be transferred
Energy Transitions: Heating Water

The seeped rainfall mentioned earlier is
  heated by the magma--
(the system is the water)
                   KE                PE
 System

And here’s why: the temperature of the water goes
up (the increase in kinetic energy), and goes
through a phase change (the increase in potential
energy).
  Energy Transitions: From Water to
          Steam- Way #1
 Sometimes, the magma is hot enough close to the
  surface that the water turns to steam-- and the
  temperature is over 300ºF. (gains PE and KE)
 The steam is trapped and is used to move a turbine--
  (system = water/steam)
 And here’s why: the temperature of the water goes
  down (decrease in kinetic energy),
  and undergoes a phase change                   KE PE
  (decrease in potential energy).
                                         sys
 Plants that use this
  system are called Dry
  Steam Power Plants.
Energy Transitions: From Water to
  Steam- Way #1-- A Visual Aid
                 Turbine                    Generator             Load




                                                   Rock Layers

        Production Well           Injection Well




             http://www.nrel.gov/geothermal/geoelectricity.html
  Energy Transitions: From Water to
          Steam- Way #2
 Geothermal water can also come in the form of
  high-pressure, very hot water.
 That water is then depressurized (known as
  flashed to those science types) to produce
  steam (gains PE and KE)
 The steam is trapped and used to move a
  turbine (see slide 5 for energy transfers-- they
  are the same.)
 Plants that use this system are called Flash
  Steam Power Plants.
Energy Transitions: From Water to
  Steam- Way #2-- A Visual Aid
                                                              Load
     Flash Tank      Turbine            Generator




                                                Rock Layers
                               Injection Well
            Production Well
 Energy Transitions: From Water to
         Steam- Way #3
More often, water in a geothermal
 reservoir is between 100º and 300º F.
To use this water, it is pumped to a heat
 exchanger, which transfers the heat from
 the water to a liquid with a lower boiling
 point- most often a hydrocarbon. (1)
The hydrocarbon becomes steam to turn
 the turbine. (2)
Plants that use this system are called
 Binary Cycle Power Plants.
Energy Transitions: Binary Plants
 1: system: water
 1: here’s why: the water undergoes a phase change (gas to
  liquid) (the decrease in PE), but is still hot (the small
  increase of KE)
 2: system: hydrocarbon
 2: here’s why: the hydrocarbon goes from a gas to liquid
  (phase change; decrease in PE). The temperature goes
  down (decrease in KE)
    1:      PE      KE           2:      PE      KE
    Sys                          Sys
Energy Transitions: From Water to
  Steam- Way #3-- A Visual Aid
                 Turbine            Generator             Load




                              Heat Exchanger




                                            Rock Layers
        Production Well    Injection Well
Energy Transitions: The Generator
The turbine is moving- in any of three
 different ways- what next?
The turbine is connected to wires inside
 the generator and moves them through a
 magnetic field. (1)
The movement causes an electrical
 current to flow in the wire. (2)
The wire is connected to a light bulb-- and
 makes it light up. (changes in energy on
 next slide.)
Energy Transitions: The Generator 2

1: system: turbine
1: here’s why: the turbine has been
 moving and will continue to move at the
 same pace (no change in KE).



1:    KE    PE

Sys
Energy Transitions: The Generator 3
2: system: generator
2: here’s why: electricity is flowing
 electrons moving along the wires to light
 the light bulb (increase in KE). The
 electrons all have the same charge-- and
 by being next to each
 other, they rebound off 2:          KE PE
 each other, increasing
 their potential energy.     Sys
 And Finally, a Generator Visual Aid




The wires are red in this example, and they are moved
through the blue magnetic field by the crank-- the
turbine in the geothermal world. This creates an
electrical current through the red wires, which are
connected to the light bulb-- and it lights up!



               http://www.wvic.com/how-gen-works.htm
Geothermal Areas in California
 There are 25 geothermal areas, and 14 of them
  use dry steam or flash steam power plants.
 San Bernadino has the largest geothermal use--
  directly heating 37 buildings
 Geysers (a real city) was the first city in
  California to utilize geothermal energy-- starting
  in 1960 -- it is one of only two locations in the
  world that can use a dry steam plant- and the
  only location in the US
 California produces 40% of the world’s
  geothermal energy, and in 1999 geothermal
  produced 4.9% of California’s energy.
Sustainability and Renewability
 Magma is natural- and always producing heat.
 Natural rain and snowfall keep geothermal
  reservoirs full
 The water is heated up anyway-- why not use it?
 US Department of Energy says YES! It’s
  renewable!
 Some questions: Will global warming affect rain
  or snowfall?  Should we rely heavily on one
  energy source?  How do droughts play into the
  renewablility of geothermal energy?  Is this an
  option for places like India that have very little
  overall rainfall?
Bibliography
   Green, Bruce. "About Geothermal Electricity." Geothermal Technologies Program.12 Feb. 2008
    <http://www.nrel.gov/geothermal/geoelectricity.html>.
   "How an Electric Generator Works." Wisconsin Valley Improvement Company. 27 Apr 2006. 12
    Feb. 2008 <http://www.wvic.com/how-gen-works.htm>.
   "Overview of Geothermal Energy." California Energy Commission. 9 Jan. 2002. 12 Feb. 2008
    <http://www.energy.ca.gov/geothermal/overview.html>.
   "What is Electricity?" Energy Kid's Page. Nov. 2007. 13 Feb.
    2008 <http://www.eia.doe.gov/kids/energyfacts/sources/electricity.html>.

				
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