This is actually quite a good idea and I like the concept.
http://www.file22.com/?p=509

Basically, this invention utilizes the concept that water has dissolved gases and these gasses (which fish extract with their gills) can be extracted by centrifugation from the water. Therefore, all that one needs is power to rotate the centrifuge. Apparently a one-kilo battery can provide enough power to extract enough gas for a person to breathe for on hour. This seems to be a reasonable thing to do for a nuclear submarine (for example) that has the power.

Wise.