A West Texas company says it's found a remarkably simple way to slash air cargo costs as much as 65% – by having planes tow autonomous, cargo-carrying gliders behind them, big enough to double, or potentially triple their payload capacity.
Besides, if you can do it with an electrical locomotive on the ground, the energy conversion to electricity of a power plant should be better than the energy conversion of a jet engine from fuel to movement.
So imo, cheaper seems plausible, energy efficient is a maybe.
It said “cheaper” not “energy efficient”.
Wings are easy, jet engines are hard.
Besides, if you can do it with an electrical locomotive on the ground, the energy conversion to electricity of a power plant should be better than the energy conversion of a jet engine from fuel to movement.
So imo, cheaper seems plausible, energy efficient is a maybe.