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Geothermal Exploration

Introduction:

Geothermal energy is the heat from the Earth. It's clean and sustainable. Resources of geothermal energy range from the shallow ground to hot water and hot rock found a few miles beneath the Earth's surface, and down even deeper to the extremely high temperatures of molten rock called magma.

In the United States, most geothermal reservoirs of hot water are located in the western states, Alaska, and Hawaii. Wells can be drilled into underground reservoirs for the generation of electricity. Some geothermal power plants use the steam from a reservoir to power a turbine/generator, while others use the hot water to boil a working fluid that vaporizes and then turns a turbine. Hot water near the surface of Earth can be used directly for heat. Direct-use applications include heating buildings, growing plants in greenhouses, drying crops, heating water at fish farms, and several industrial processes such as pasteurizing milk.

Task:

GeoPower Corporation (a developer of geothermal sources) has recently completed drilling three 1,800 foot deep exploration holes in an attempt to locate a geothermal resource thought to be in the Eastern part of Arizona. The holes were filled with water, and after several weeks, the water temperature became the same as the temperature of the surrounding rock. Readings of the water temperature at every 200 feet were taken to determine how the temperature changed with depth.

*A temperature of at least 300 °F is needed to make use of a geothermal source for electricity production.

Use the table to below to graph how temperature changes with depth in each bore hole.

(Use a different color for each line, and be sure to include a key)

Table 1: GeoPower –Eastern Arizona Exploration Results

Depth (Feet) / Bore-Hole #1 (°F) / Bore-Hole #2 (°F) / Bore-Hole #3 (°F)
200 / 40 / 60 / 42
400 / 40 / 85 / 44
600 / 42 / 105 / 50
800 / 44 / 115 / 55
1000 / 50 / 135 / 60
1200 / 60 / 155 / 75
1400 / 80 / 158 / 95
1600 / 105 / 160 / 120
1800 / 116 / 162 / 150

Questions:

  1. Which bore-hole would you recommend developing for electricity production? EXLPAIN WHY you chose this hole over the others!
  2. At what depth would you expect to reach 300°F in the geothermal reservoir you chose?
  3. Which bore-hole would you recommend developing for a heat pump? What are heat pumps used for and EXPLAIN WHY you chose this hole over the others.
  4. Describe each of the 3 types of geothermal power plants.
  5. Which type of power plant would GeoPower most likely be developing with this bore-hole? EXPLAIN WHY!
  6. Who are the top two geothermal producing countries?
  7. What are 2 disadvantages of geothermal power?
  8. Describe the process of producing geothermal electricity.
  9. Describe the 3 other forms of renewable electricity that were presented today.
  10. With a little research if necessary rate the 4 types of renewable electricity from 1 to 4 in terms of cost (lowest to highest)
  11. With a little research if necessary rate the 4 types of renewable electricity from 1 to 4 in terms of environmental impact (lowest to highest)