[jacquesm]

It takes a 747 quite a bit more than 2.5 minutes to reach cruising altitude. 30,000 ft at 5000 fpm is 6 minutes, and engine input is a lot higher than 90 MW because engines are not even close to 100% efficient (neither are electrical ones).

Also, the weight on landing is critical not on takeoff, and you can't exactly shed battery weight because empty batteries weigh roughly the same as full ones do, so you will need to take maximum landing weight into account.

Finally, you need to take reserve fuel into account, alternates and headwinds.

I think you should re-do these numbers with more realistic inputs.

[riazrizvi]

Reserve fuel? I didn’t even allocate any fuel to land, I am assuming passengers won’t mind the bumps at their destination, you know for the planet.

[catalogia]

There are more practical ways to reduce the population than cratering airplanes into runways.

Fuel is a major expense for commercial airlines, they don't burn it just for shits and giggles. Airplanes use fuel when landing because destroyed aircraft and piles of corpses will quickly cost more than any fuel they'd save by trying to glide every plane to the ground.