I was wondering the same thing - they don’t specify the size of a “barrel”, but charitably assuming it’s a 55-gallon drum, not a 42-gallon oil barrel, they claim to get 440 lbs of hydrogen from 412 lbs of water.
Somehow circumventing the Law of Conservation of Mass.
“, they claim to get 440 lbs of hydrogen from 412 lbs of water.”
You forgot to add in the weight of the barrel.