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Geothermal Energy

What geothermal energy is:

  • Geothermal energy is heat from within the earth.

The Interior of the Earth

Interior of the Earth
Interior of the Earth
  • Diagram:
  • Core:
    • Almost 4,000 miles beneath the surface of the earth.
    • Made of two layers: a solid iron core and an outer core made of magma (molten rock).
  • Mantle:
    • Surrounds the core.
    • Is about 1,800 miles thick.
    • Made of magma and rock.
  • Crust:
    • Outermost layer; forms continents and ocean floors.
    • Can be 15 to 35 miles thick on land and 3 to 5 miles thick under oceans.
  • Heat is always being created in the core of the earth from the slow, natural decay of radioactive particles. 
    • The temperature of the solid inner core is as hot as the surface of the sun – about 6,000⁰ C, or 10,800⁰ F.
      • Rocks and water deep underground absorb this heat.
    • The crust of the earth is broken into pieces called tectonic plates.
      • Magma comes close the earth's surface near the edges of the plates.
        • Rocks and water deep underground absorb heat from the magma.
        • When magma comes close to the surface, it heats groundwater trapped in porous rock or in underground reservoirs.
          • This heat can be recovered and used to heat buildings or generate electricity.
      • Geothermal energy is renewable because heat is continuously being produced inside the earth.   
  • Enhanced Geothermal Systems, or EGS, is a technology that produces electricity from the heat of the earth.

The process of Enhanced Geothermal Systems (EGS)

  • Hot rock is fractured;
  • Water is circulated through an underground system;
  • Steam is created;
  • The steam drives a turbine to generate electricity;
  • The water is run back through the rocks to pick up more heat;
  • The closed-loop cycle begins again.