It is one of the "Hydrogen" systems that use "surplus" alternator power to use electrolysis to split water and feed the hydrogen into the intake.
We discussed it a while back in a
classic Dean vs. Scott battle I have no urge to repeat.
The unproven theory is that hydrogen changes the combustion characteristics to provide more complete combustion and/or faster flame front.
I still think the Mythbusters need to test it.