Science

I'm an old man.

This is not an energy source, but it's a well known, very well known, energy storage device which is, by the way, extremely energy inefficient, since aluminum is reduced electrolytically and, since aluminum reduction is a major source of carbon tetraflouride in the atmosphere - along with semiconductor processing - a general approach to accelerating climate change by a great deal.

Carbon tetraflouride has an atmospheric half life of approximately 50,000 years, and a global warming potential that is over 7000 times as large a carbon dioxide.