What is the major problem in using geothermal power?

Some of those cited are pollution, waste, conversion, and corrosion.

Releasing poisonous gasses

1. May Release Harmful Gases : Geothermal sites may contain some poisonous gases and they can escape deep within the earth, through the holes drilled by the constructors. The geothermal plant must therefore be capable enough to contain these harmful and toxic gases.
2. Transportation : Geothermal Energy can not be easily transported. Once the tapped energy is extracted, it can be only used in the surrounding areas. Other sources of energy like wood, coal or oil can be transported to residential areas but this is not a case with geothermal energy. Also, there is a fear of toxic substances getting released into the atmosphere.

It has caused earthquakes. Countries that has openly reported these problems include Germany, Switzerland, and United States.