Urine is put into an electrolytic cell, which separates out the hydrogen. The hydrogen goes into a water filter for purification, which then gets pushed into the gas cylinder. The gas cylinder pushes hydrogen into a cylinder of liquid borax, which is used to remove the moisture from the hydrogen gas. This purified hydrogen gas is pushed into the generator.
And what is doing all of the pushing?
They harness the bladder pressure of guys who haven't peed in a couple days.