the energy they receive is directly from the magnetic fields surrounding city electrical grids the lust for brains is because of an anthropomorphic realization that they dont think as good as they used to. You can disassemble them but the parts keep moving. Dunno how muriatic acid would work though

that convention is an old one from the fifties, the original zombies were field hands that worked with no free will.
http://zombies.monst...ming_a_zombie.htm

Haitian Penal Code:
Article 249. It shall also be qualified as attempted murder the employment which may be made against any person of substances which, without causing actual death, produce a lethargic coma more or less prolonged. If, after the person had been buried, the act shall be considered murder no matter what result follows.

thats the old school version, now new school is a viral state which from external observation (watching the movies) an ebola like hemorrhagic fever grips the infectee, the heart stops then the corpse starts moving while mumbling brains.

In the dawn of the dead cycle, the shopping mall had zombies that were just wandering around bumping of of walls until they came close to a living person then became animated to infect. So they cycled a long time with no apparent source of nutrition except for florescent light. That just leaves magnetic force from the power grid as the alternative.