Geothermal energy

Geothermal energy is a scientific term used to describe the amount of energy a planet could produce from internal heat generated by the core. Some planets with surplus energy trade it for goods needed, for example construction materials.

During the 15th century, the Vaadwaur utilized an efficient means of drawing energy from their planet's geothermal core. 

On the moon of Andoria, Andorian cities were built underground to take advantage of the moon's geothermal energy. 

The planet Deneb IV had abundant reserves of geothermal energy. The energy was used to hold a space creature captive, a being able of forming itself into any shape the captors wanted – in this case, Farpoint Station. Eventually, the crew of the USS Enterprise (NCC-1701-D) freed this creature from its tormentors. 

On an unnamed asteroid in the Delta Quadrant, a group of Talaxians established a colony where they dug several tunnels and used the asteroid's geothermal energy to melt the ice that covered most of the outer surface, which provided them with oxygen and water. That technology was later given to Nocona and was converted into fuel used to power his ships.