Introduction
Cities, as well as individual homes, can use geothermal energy to heat and cool buildings efficiently, lowering electricity use and pollution. This hands-on activity simulates how underground soil maintains a relatively constant temperature and can exchange heat with water. Students will observe thermal energy transfer using simple materials and visualize how geothermal systems work.
Materials
Per Group
- Student Handout
- 2 clear containers filled with soil (one chilled overnight, one at room temperature)
- 2 resealable plastic small Ziploc bags
- 2 liquid crystal thermal temperature strips
- 2 measuring cups or beakers
- Warm water (~40-45 degrees Celsius)
- 2 pipette droppers (or other tool to drip water slowly)
- Timer or stopwatch
Student Objectives
Students will be able to
- Describe how geothermal energy involves heat transfer between underground soil and fluids.
- Observe and compare how temperature changes in different soil conditions.
- Explain the basic principle of geothermal heating and cooling.
- Reflect on how natural energy sources can support sustainable city design.
Procedure:
- Give each student or student group a copy of the Student Handout
- Divide the students into groups and provide them with the materials to start the experiment.
- Once students have completed the experiment, have them answer the reflection questions to analyze their observational data and draw conclusions.
Big Ideas
The temperature strip in the chilled soil should show a bigger temperature change as it pulls heat from the water. The temperature strip in the room temperature soil should show less change, demonstrating less cooling.
This shows that underground soil can absorb heat or stay cooler than the air above. It acts like a sponge for thermal energy. Because soil underground stays at a steady temperature, it can either pull heat away when it’s hot or give off heat when it’s cold—like a natural heater or cooler.
Answer Key
The Student Guide contains the Heat Transfer Lab – Student questions.
Reflection Question Sample Responses
Question 1: The container with the chilled soil showed the bigger temperature change. This is because the cold soil absorbed more heat from the warm water, causing the temperature strip to cool down faster. The soil at room temperature didn’t need to absorb as much heat, so the strip didn’t change as much.
Question 2: This shows that underground soil can absorb heat or stay cooler than the air above. It acts like a sponge for thermal energy. Because soil underground stays at a steady temperature, it can either pull heat away when it’s hot, or give off heat when it’s cold – like a natural heater or cooler.
Question 3: If we use underground pipes filled with water, they can carry heat to the buildings in winter, and take heat away in the summer. This reduces the need for air conditioners or heaters, which use electricity.
Question 4: Answers will vary.