In my Singularity’s Children books, huge Sky Whales and floating party dirigibles use electrohydrodynamic (EHD) thrusters to generate lift and thrust. I imagine these a silent and ethereal, a near-future alternative to anti-gravity.
The tech is not pure ScFi, there are already ion-drives operating in space, but their use for atmospheric propulsion is still a way off.
A bit of background: Jet engines create thrust by burning vaporized fuel in compressed air. The combustion creates a controlled explosion which drives air out the back generating thrust to push the aircraft forward, while also turning the intake compressor to grab up more air.
Magneto-Plasma thrusters, on the other hand, use electricity to produce an ionized gas (plasma) and accelerate it with electric or magnetic fields up to extreme velocities. They frugally create thrust from a small amount of propellant traveling very fast.
These super-efficient engines are currently confined to vacuum, e.g. station keeping satellites or propelling interplanetary probes, but I was super interested to read that the first atmospheric, air-breathing, magneto-plasma jet engine has been successfully prototyped.
The European Space Agency has just demoed similar technology for operating at the edges of the atmosphere, sucking in and ionizing air rather than carrying propellant.
As I have mentioned before, writing near-future SciFi is a real race against reality!!