@Tfmonkey I would also like to add that the problem with hydrogen isn't that it takes heavy tanks to store (you're thinking of methane/natural gas). The problem is that hydrogen can't even be stored in a tank at all (it literally passivates through any material). So you need to store the hydrogen in materials called hydrides. The problem is that all the hydrides that actually work well are illegal because they are critical components to thermonuclear bombs thus are ITAR materials.