Water Electrolysis as an Energy Source

I understand that classical perpetual machines are impossible, because they invariably generate less energy than they consume. However, I wonder: (1) if there might be more energy inherent within Hydrogen & Oxygen than is required for the electrolysis of water; and (2) if such efficiency in electricity generation as necessary to perpetuate said electrolysis is achievable by the combustion of thoes elements.
- Austin (age 17)
Austin, Tx, Usa

The laws of thermodynamics apply very generally, not just to some particular classical systems. The free energy required to electrolyze water is always greater than the work obtained when the oxygen and hydrogen recombine. We've addressed this in some related questions:
https://van.physics.illinois.edu/qa/listing.php?id=16490; 
https://van.physics.illinois.edu/qa/listing.php?id=3698; 
https://van.physics.illinois.edu/qa/listing.php?id=20086; 

Mike W.

(published on 02/07/2016)