But where would I start?
And how much electricity would it take to produce Hydrogen?
what other kind of powerplant could I build?
I want to go off the grid
I am afraid solar power is still too weak. (costly)

With present technology hydrogen is very costly,dangerous to make and dangerous to store. The hydrogen molecule is so small that under the high pressures required for storage, it will seep through the walls of a steel tank.

you need to do some more research i think.

If you are producing your own hydrogen through electrolysis you are going to use more power then you can get back out of it. Which is what it sound like you want to do for some reason.

if you hare just planing to get fuel cells or a generator that burns hydrogen you will need to find someone who will sell you hydrogen and have some big tanks to store it in. Still who ever you get it from will use the grid for the power to make it.

hydrogen is not a source of power we don't have free hydrogen just sitting around. It is a storage medium like a battery. If you ran your house from batteries you would need to charge then => still need the grid.

the only ways you can make your own power without burning fossil fuel are solar, wind, water turbine(if you have a steep slope and a stream in your yard(that would so rock)), or grow stuff to burn(like trees then you have a boiler hooked to a steam turbine and generator).

One where you still relay on others but not as much on fossil fuel that is feasible would be to get a diesel generator and make a deal with some local restraints for the grease from there deep fat fryers. Then you just filter and correct the pH of the grease and you can run it thought there and have your house off bio-fuel.

Producing and storing hydrogen safely is very expensive. It requires massive amounts of equipment. You can set your house up for solar energy and sell power back to the power company much more cheaply than you think. I know of a few people who have done it.