Coal is an abundant dark colored resource found on the majority of planets. It is most players first source of power as it is the simplest.
It can be used for two types of setups, Coal-Based (Which directly converts coal to power using BurnerGenerators) and Steam-Based (Which uses coal in a Boiler to convert Water to Steam which gets turned into power).
Outside of power generation, it can be used to produce Plastic.
In-game Description
"A natural resource found abundant in mountains, and is commonly used as a source of generating heat and energy. Can be placed in a BurnerGenerator to generate energy."