It is Radioactive Decay.
The volcano may not be a type of geothermal energy but lava is surely a type of geothermal energy.
geothermal energy and solar energy
geothermal
The oldest energy known to man is Geothermal energy.This geothermal energy originates from the original formation of the planet, from radioactive decay of minerals, and from solar energy absorbed at the surface. It has been used for space heating and bathing since ancient Roman times, but is now better known for generating electricity
The primary use of geothermal energy is in the agricultural industry. This type of energy is the primary source of heat in greenhouses.
The primary use of geothermal energy is in the agricultural industry. This type of energy is the primary source of heat in greenhouses.
renewable
renewable
Geothermal energy
renewable
Geothermal energy - electricity.
gamma decay