A recipe for zero-emissions fuel: Soda cans, seawater, and caffeine

Ignoring the catalyst that are missing in the silly title ...

The main part is an easy redox reaction

  4 Al + 6 H2O  -->  4 Al2O3 + 6 H2

and then burning the H2,

  6 H2 + 3 O2  -->  6 H2O

so the global reaction is

  4 Al + 6 H2O + 3 O2  --> 4 Al2O3 + 6 H2O

I can't understand how this can be better than just using the metallic aluminium as the anode of a battery. In the battery, you get all the energy stored in the metallic aluminum, but if you use Hydrogen as an intermediate step part of the energy is released and wasted in the first reaction.

Also, metallic aluminium is easy to recicle, but once it's oxidized it's hard to transform it again into the metallic form.