It didn't take me long to see that the energy released in the combustion of hydrogen might be more than the energy required to split water.
This is so not true,...get thee to a community college and take physics...read about James Prescott Joules.
I will even describe the experiment for you…
You build a Hydrogen/oxygen generator entirely inside of a calorimeter, measuring the energy going into the splitting of the hydrogen from the oxygen. Then you burn the hydrogen and oxygen derived thusly inside another calorimeter and measure the resulting energy. The resulting energy will be the same that went into the first calorimeter, minus the inefficiencies of the process.