In my world, 500 years in the future, my population fits anti-gravity engines to salvaged boats as a form of transport. These transports fly close to the Earth's surface and are powered by a highly efficient solar panel system rigged as sails.
I'm struggling to come up with a design to propel the boats along, and the only concept that I can think of is propellers driven by electric engines.
Is there a more efficient/effective engine design that I can utilise?
- Fossil Fuels are depleted, and cannot be used.
- The largest of transports being Cargo Ships must travel at a minimum of 25 knots, and the smallest at a minimum of 45 knots.
- Fuel sources required for the engine must be in abundant supply and easy to manufacture or contain or, if a reactor is required - able to be stationed onboard the vessel and be maintained by an engineer.
- The engine must run as cleanly as possible. (As few emissions as possible)
EDIT: This question has been flagged as a duplicate due to another question that I have asked in the past. I believe that this question is not a duplicate as I am looking for a propulsion system, not an anti-gravity engine that could propel my transports. (In this case they cannot due to how my anti-gravity engines work.)