Re: Small steps...
I'm not going to downvote you, but analyze each of your ideas as simply as possible so you understand maybe why so many people are being 'negative':
1. That's called a blimp or a rigid airship, not a plane. H2/He is lighter than air, but metal, people, and batteries are far, far proportionally denser than air. Therefore you need a massive volume of lifting gas relative to the aircraft, which becomes a whole new set of engineering problems beyond an airplane.
2. This is at least a plausible idea, but I would guess that given the weight of two sets of engines this wouldn't be worthwhile. A jet engine that can run on both hydrocarbons and by electricity seems like it would be too much of a compromise in either direction. Ground-assist takeoffs for short transits may be more practical, such as the plane drawing electrical power from the runway until it gets airborne or maybe even a scaled-up carrier slingshot.
3. That's called a 'battery', electrochemistry is the principle behind batteries, lots of chemists are always working on better ones, and wanting batteries that can be recharged seems to impose some engineering restrictions on what chemicals can be used.
Biting the hand that feeds IT
