What energy does the capsule use?

At present, the fuels used by spacecraft are all chemical fuels, some are kerosene, some are hydrazine and some are liquid hydrogen. Of course, there are also essential oxidants, mostly liquid oxygen. The principle is that the chemical fuel is mixed with oxidant in the combustion chamber of the engine to produce high-temperature gas, which is ejected backward from the nozzle, and the spacecraft is pushed forward by the principle of acting force and reaction force. Some small engines used by spacecraft to control flight attitude use compressed gas. By using the switch, the compressed gas is ejected for a short time, which produces a reverse force and changes the attitude of the spacecraft. This is not fuel.