The goal of this project is to demonstrate the different levels of the Earth's interior. Bring Play-Doh or colored clay for each student, or create one Earth for the entire class. Roll a small red ball to be the inner core. Wrap additional layers in different colors around the small red ball. Use separate colors for the outer core, the mantle and the crust. Let the model of the Earth dry overnight and slice it in half in the morning to reveal its cross section. Use the model to explain to the class where the heat originates from and how it can reach Earth's surface.
Once the basics of geothermal energy have been established, take it to the next level by showing the class how thermal energy works. Using a plastic 1-liter bottle, large balloon, bowl of hot water and bowl of ice water, a class can learn how geothermal energy is an effective energy source. Cool the balloon and the bottle in a freezer for about five minutes. Meanwhile, fill the bowl with hot water. Put the balloon over the mouth of the bottle and place the bottle in hot water. The air inside the bottle will expand and inflate the balloon. When the bottle is placed in cool water, the balloon will deflate.
This project will teach students how steam is used to turn a turbine attached to a generator to make electricity. Gather a small pinwheel, aluminum foil, an empty soup can, a wooden ruler, a small cooking pot, a hot plate, a hammer, nail, tape and pot holder. Using the hammer and nail, punch a hole in the end of the tin can near the edge. Punch another hole across from it. Attach the ruler to the can with rubber bands. Then, put water in the pot and cover the top of the pot with two layers of tin foil tightly. Using the nail, punch a hole in the top of the tin foil cover. Put the pot on the hot plate and bring to a boil. When steam comes out of the top, hold the pinwheel over one hole and notice how fast the pinwheel spins. Take the can on the ruler and place it on top of the pot. You should now see steam coming out of the top of the can through the two holes. Again, hold the pinwheel so that the holes are on opposite sides of it. Notice how fast the pinwheel spins now! It is that energy coming from the steam that powers larger geothermal power plants.
One of the most common and beloved science fair projects is an exploding volcano. This is a demonstration of geothermal energy. Making a volcano out of paper mache; it is easy to make the volcano erupt when the time comes by adding detergent and baking soda to the water that is in the volcano. Place the mixture in a bottle and place the volcano over it. Pour some vinegar into the bottle and watch it erupt. Explain to the class that this is an example of geothermal energy that naturally occurs under the Earth's surface. This is also a great introduction to a chemistry lesson.