Geothermal Energy

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Geothermal Energy
2013-12-06 23:00:53
Geothermal Energy

Geothermal Energy
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  1. Earth core temp
    Reaches a max temp of 4000 Celsius
  2. Heat transfer type through earth
  3. Average geothermal heat flow at the surface
    • g = 0.06 W/m^2
    • delta T = 30 Celsius per km
  4. Dry steam plants
    Use steam from geothermal reservoir as it comes from wells and route it directly through turbine/generator units to produce electricity
  5. Geysers
    • Opens systems
    • emit some air pollutants (H2S) and trace amounts of arsenic and minerals
  6. Flash Steam Plants
    • most common
    • water at 182 degrees pumped at high pressure
    • P is suddenly reduced, some of the hot water is flashed for the turbine/generator
  7. Flash
    Converted into steam
  8. Binary Plants
    The water from the reservoir is used to heat another working fluid which is vaporized and used to turn the turbine
  9. Binary Plant advantage
    • Operate with lower temp water (107-182)
    • Use working fluids with lower boiling point
    • Don't produce air emissions
  10. Geothermal Energy
    heat from the earth
  11. Most US geothermal reservoirs are located:
    western states, Alaska, Hawaii
  12. Types of geothermal power plants
    • dry steam
    • flash steam
    • binary cycle
  13. Dry Steam Plant Diagram
  14. Flash Steam Plant Diagram
  15. Binary Cycle Plants Diagram
  16. Geothermal Direct Use
    • Reservoirs can be used to provide heat directly
    • i.e. using the hot water to heat up a room

    A well is drilled into a reservoir, the water is brought up the well and a mechanical system delivers the heat directly
  17. Geothermal Heat Pumps
    Winter: The pump removes heat from the exchanger and pumps it into the indoor air delivery system

    Summer: The pump moves heat from the indoor air into the heat exchanger
  18. Geothermal Advantages (6)
    • No by-products
    • No fossil fuels
    • No greenhouse effect
    • Little maintenance
    • Self-sufficient 
    • Small plants
  19. Geothermal Disadvantages (5)
    • Area must have suitable hot rocks
    • Particular type of rock (for drilling)
    • Harmful mineral and gas can escape from underground
    • Pollution due to improper drilling
    • Area can run dry