Purrpetual Energy

Purrpetual Energy is a cat-themed superfuel.

It is accepted by most power generators (from Alternator Generator to Quantum Reactor), but because it requires non-craftable Kitty Hat or The Un-Cat Hat, it can't be obtained in any meaningful quantities.

Lore
Cats always land of their feet, and sandwiches with butter always fall "butter to the floor", so if we tie a sandwich to the cat's back, it will rotate infinitely. This rotation powers the reactor.