I've seen a number of back of the napkin calculations involving electric airplanes, but even when compared with fuel cells, traditionally fuelled airplanes have

I've seen a number of back of the napkin calculations involving electric airplanes, but even when compared with fuel cells, traditionally fuelled airplanes have the advantage that their weight greatly decreases as they use fuel. Apparently a significant portion of the range of an airplane comes from when the tanks have < 50% fuel. This shifts the economics even further in their favour, aside from simple energy density calculations (as you're lugging the now useless, yet still very heavy batteries / fuel cells all the way to the destination). While I'd love to see a shift in a more sustainable direction, I wonder if we're going to be close to that anytime soon.