Uh, standard automotive starting battery technology has evolved quite a lot in the past 150 years. There are two types of SLA batteries rather than the old type you require water for, which are more durable and last longer and produce more power per density. They suspend the acid in wildly different ways (one with a glass microstructure, one with a gel, IIRC) instead of sloshing it into open cells. To say that the basic technology is the same is to say that the basic technology of rocketry is the same as the basic technology of cars--burning fuel to move things has always been a thing, but rockets, scram jets, and combustion engines all operate on wildly different principals (for one, burning fuel like that at high altitudes and high speeds to get thrust doesn't actually work--RAM jets and SCRAM jets are made specifically to compress and ignite fuel in ways that don't work at low speeds, and rocket engines have their own design considerations).
Water isn't a high-density fuel. Natural gas is usually stored at 500PSI in adsorption tanks, whereas with just a steel tank you can stuff the same amount of fuel in there at 4000PSI. How much PSI do you think the freed hydrogen from 1gal water would be under stuffed in a 1gal jug?
'dependency hell' doesn't sound like a thing to me. People complain about 'dependency hell' in Fedora/RPM and in Deb, all the time. That's everyone's excuse for running away from stupid broken Redhat and for running away from stupid broken Debian. I've run into dependency issues where I had to knock a package out because neither Yum nor Apt is smart enough to iteratively construct a dependency graph until convergence. I can probably trigger it in a few known cases (install Puppet 2.7, then add the puppetlabs repo and install Puppet 3.0... on Ubuntu 12.10) and get it added to apt, while Yum will probably lag behind forever. Note that the same happens with i.e. Percona, if you switch to Percona-Cluster-XtraDB from just Percona-Server... it can't reconcile that it needs to remove the Percona-Server-shared package (which is required for a dependency) and replace it with Percona-Cluster-XtraDB-shared (which satisfies the same dependency), so you have to rpm -e --force it and then install the package and Yum is happy.
Of course, in apt you can just apt-get -f install and it figures out what's wrong and fixes it. (-f means 'fix', and -f install fixes whatever's broken by installing the correct thing, replacing dependencies as needed without crying about it).
It's completely stupid anyway.
Consider when you burn 2H2 + O2 you get 2H2O + heat. That means you need energy to go from H2O to H2 + O. Heat, current, something.
Catalytic water reaction: Will eventually freeze itself. It may reach absolute zero; probably not nearly. Will require heat input.
Non-catalytic water reaction: will take as much energy to produce the fuel as is required to break down the water, at least. Really, more energy in (and lost) than energy out. Catalytic recycling of the reactionary products of the fuel would absorb heat, see above.
To be honest, I'd be much happier if Redhat/Fedora leveraged a more Debian-like system. I mean, with systemd and all; but call apache2 apache2 instead of 'httpd' (isn't nginx httpd?), have
Quantity is no substitute for quality, but its the only one we've got.