[azernik]

Unfortunately, aerospace is a place where energy density really really matters. If your car's battery weighs twice as much as equivalent hydrocarbon fuel, that will decrease your range, but probably won't affect your performance or total energy usage all that much.

For planes, however, using a more environmentally-friendly but heavier energy storage medium is self-defeating, because you have to spend a lot more energy lifting the extra energy-storage weight. Unfortunate, but it is what it is.