Batteries are getting lighter and lighter as density increases. Also, you can use batteries as part of the structure, making them take over necessary functions.

Batteries are getting lighter and lighter as density increases. Also, you can use batteries as part of the structure, making them take over necessary functions. Next generation batteries like sulfur-silicon can power a personal car and are the size glove box and can be carried by a person. That is a decade away at least but its very promising technology. I have no problem with producing green CH4 to continue to run legacy systems.