Propulsion - Harvested Energy, Internal Reaction Mass

Energy is gathered from the surrounding environment, and used to expel reaction mass for thrust.

If the power supply is solar panels gathering electricity, you have a solar-electric rocket system. The power supply dominates vehicle performance in this case, and any of a variety of electric thrusters may be used, such as:

Ion Engine

If the power supply is a 'windmill', extracting energy from the flow of surrounding space plasma past the vehicle, you have:

q-drive