They are not as efficient as those powered by fossil fuels, but they work.
Problem is, fossil fuels can be almost any chemical fuel. They are about as densely populated as possible without being explosive. They still weigh more per unit of energy delivered. Even if they could match fossil-fuels’s weight, batteries still weigh more per unit of energy delivered.
Alternativly, solar cells could be used if you don’t have batteries. There are two issues with this.
- What do you do at night? You still need a big battery
- Solar cells are also not very energy-dense. There isn’t much space between the wings and the back of a plane. This is low energy output at slow speed.
My conclusion is that although electric flight is possible, it is not practical.
However, lighter than air travel is a completely different proposition.
Air blimps that are lighter than air have a problem with fossil fuels. They can’t stay neutrally buoyant while burning fossil fuels simultaneously. You will sink if you don’t release enough lifting gas.
Blimps work by being heavier than air and then using engine power to lift them off the ground. Because you can remain buoyant and constant in weight, this is actually a benefit. Electricity makes perfect sense when you consider that lighter than aircraft have low energy requirements and lots of space on the top to house solar cells.
Lighter than air vehicles aren’t very popular, except for the Hindenburg. We could not prevent this day, even if Hydrogen was available in blimps. The Hindenburg was able to travel at 80 MPH/130 KPH. Modern jet liners go about seven times faster.