Metal hydrides as alternative energy source?

I have an oral presentation to do on Metal hydrides as an alternative energy source. I tried to do some research on metal hydrides and all I come up with are published scientific research papers and people selling cells of metal hydrides.

I don't want you to do my homework for me; I want to do it myself. But, could someone give me like an introduction or overview of Why/how is metal hydrides an energy source?

Thanks and 10 points for best answer!