Exploring Low-Temperature Geothermal Energy

Activity Source: American Association of Petroleum Geologists

 

Background

Geothermal energy harnesses Earth’s internal heat to generate power. Typically, it involves tapping into high-temperature reservoirs of hot water deep beneath Earth’s surface. However, as the demand for clean energy grows, researchers are developing innovative techniques to access common low-temperature geothermal sources found closer to Earth’s surface. New technologies broaden the geographic reach of geothermal energy, making it a more accessible and sustainable energy option.

Materials

  • PVC pipe with end caps (6–10 ft length; - 2 in diameter recommended)
  • 2 liquid bulb thermometers (one with an attachment to hang it)
  • Measuring stick or tape
  • Post hole digger
  • Heavy-duty string or twine
  • Scissors
  • Duct or other heavy‑duty ​tape
  • Drill (optional)

Procedure

  1. With approval, use a post hole digger to create a hole 2 ft shorter and slightly wider than your PVC pipe.

  2. Cap one end of the pipe, and place that end into the hole. Pack soil around the pipe.

  3. Drill a small hole in the middle of the second end cap.

    a. Cut a piece of string that is about 1 ft shorter than the pipe.

    b. Thread the string through the hole in the end cap and secure with duct tape.

    c. Tie the other end of the string to a thermometer.

    d. Gently slide the thermometer into the pipe and cap the top of the pipe.

  4. Tape the second thermometer to the outside of the pipe so you are still able to read the temperature.

  5. Wait at least 1 day.

  6. Record weather conditions and the temperature from both thermometers. Work quickly to take the internal temperature to prevent heat exchange with the environment.

  7. Repeat steps 5 and 6 for at least 10 days at approximately the same time each day.

Analysis

  1. Graph your data with both the interior and exterior temperatures on the same axes.

    a. Describe and compare the trend for both sets of data. Explain these trends.

    b. Read about and summarize the uses of low-temperature geothermal energy.

  2. How might your results differ with a longer pipe? Explain your reasoning.

    a. Study Figure 1 on this website. How does this data compare to your hypothesis?

    b. Why do you think there is a different trend at different locations?

  3. Study a map of geothermal potential across the U.S.

    a. What do the areas marked with high potential all have in common?

    b. This map considers areas with high temperature reservoirs. How would this map change if it showed low‑temperature geothermal potential?

Further Steps

Read more about “New Geothermal Energy ​Directions”.

NGSS Connections

  • SEP: Planning and Carrying Out ​Investigations
  • DCI: ESS3.A: Natural Resources
  • CCC: Energy and Matter

SDG Connections