I did some math on it, I'm not a chemist but it doesnt look good
I used the Punch HHO High-Output for an example ($300 HHO unit)
The Punch makes 72L of HHO per hour using 20 amps at 12 volts
HHO is 2/3 Hydrogen and 1/3 Oxygen, so 48L of Hydrogen
48L of Hydrogen is 550BTU
20amps at 12v for 1 hour is 240 watt-hours, or 819BTU
So you put in 819BTU and got 550BTU out of it - a waste, but it gets worse
The alternator that supplies the energy to the HHO unit is only 55% efficient, so it actually took 1489BTU from the motor
And then the motor is only 20% efficient, but lets say its a super high compression with a super efficient turbo and throw in some alien tech to make it 50% efficient. In that case it took 2978BTU of fuel to make the 1489BTU the alternator needed.
So in the end you have spend 2978BTU of fuel to make 550BTU of Hydrogen
