Thermal Power - sswelm/KSPInterstellar GitHub Wiki
Thermal power is generated by Reactors and Microwave Thermal Receivers. It is consumed by Electrical Generators, as well as the Thermal Rocket Nozzle and Thermal Turbojet.
Thermal power is measured in megajoules (not to be confused with MegaJoules, another resource which represents electrical power). The rate at which thermal power is produced is determined by the power rating of the reactor. A 1 gigawatt reactor produces 1000 megajoules of thermal power per second.
Generators convert megajoules of thermal power into megajoules of electrical power according to their efficiency rating.