What is the energy generated from the Earth's internal heat referred to as?

The energy generated from the Earth's internal heat is referred to as geothermal energy. This form of energy originates from the heat produced within the Earth, primarily due to the decay of radioactive materials and the residual heat from the planet's formation. Geothermal energy can be harnessed for various applications, including electricity generation and direct heating.

Unlike solar energy, which comes from the sun, or fossil energy, which is derived from organic materials over millions of years, geothermal energy provides a reliable and constant source of power that is not dependent on weather conditions or time of day. Additionally, nuclear energy is generated from nuclear fission processes and does not relate to the earth’s internal heat. Thus, geothermal energy is the correct term to describe energy derived from the Earth's internal processes.