Environment & Energy

Something is ALWAYS lost, that something being energy. You lose LESS energy using a catalyst than you would without it, but to claim absolutely nothing is lost in the transformation would essentially be creating a perpetual motion system.

http://www.4college.co.uk/as/atm/catalysts.php

That's not to say this isn't a VERY promising development. You just have to tie it into an energy source that's renewable (such as solar and wind), because you need an external energy supply to both crack water into hydrogen and push the reaction. The same goes for the idea of using CO2 as a fuel stock; you just need a way to extract and compress it to high enough concentrations.

It also has the benefit of being a way to store renewable energy without requiring massive battery banks or large hydro systems.