Geothermal energy uses heat from rocks and fluids underground to make electricity and heat buildings. It creates very little pollution. To make electricity, the rocks need to be very hot, over 100°C. For heating, a range of temperatures can be used for things like heating homes, pools, and greenhouses. Scientists are finding new ways to get heat from the Earth even when there isn't much fluid underground. This will help us use more of the Earth's heat for energy.