A certain form of energy does not cause any pollution and is easily converted into electricity. It is not obtained directly or indirectly from the Sun. It is technically very difficult and expensive to obtain this form of energy and it is not available everywhere. What is this form of energy called?

The heat energy present within the Earth is known as geothermal energy. This energy is not obtained directly or indirectly from the Sun.

However, this energy is not distributed equally throughout the earth and is concentrated in specific places, this makes geothermal energy extraction an expensive procedure. Geothermal systems can be found in regions with a normal or slightly above normal geothermal gradient, especially in regions around plate margins where the geothermal gradients may be significantly higher than the average value.