My Earth is similar to our real Earth, and some scientists have found out a really cheap way to use geothermal energy. Huge generators are built, but one scientist eventually found out that the Earth is not as hot as it was before this huge usage of geothermal energy. The Earth gets colder inside and nobody can stop the cooling. Soon enough, the Earth liquid core has become just like a huge rock.
My question is: are there any catastrophes that are likely to happen, or what will happen? (These power stations will stop working and there is a really big need of power) or will just everything run as it is and there will be no volcanoes or earthquakes any longer (because the energy responsible for the movement of the tectonic plates is no more)