I only have high school chemistry but know you don’t get to split water, make hydrogen, for free. It takes energy and in this case it’s supplied by aluminum which is quite expensive. In supplying this splitting energy the aluminum becomes aluminum oxide. To reuse the aluminum oxide you turn it back into aluminum by electricity.
I fail to see what’s so clever about this scheme
Nothing that I can see either other than it may be more energy dense than batteries. For that matter you could run a car on calcium carbide and water, but no one does it. might be a good test bed for this process