A man who has studied the issue. I do advocate tapping geothermal sources such as Yellowstone to create electricity to hydrolyze water into hydrogen and oxygen. there is enough magma in Yellowstone close to the surface to fullfill all the energy needs for the US for tens of thousands of years. There is a tempature catalized method of storing hydrogen that make high pressure storage tanks unecessary on vehicles. Mercedes pioneered this technology for bus fleets.
Ditto on your idea for Yellowstone. This would be an almost inexhaustible heat source for energy/hydrogen production, and it would also serve the dual purpose of relieving pressure and removing energy from the coming volcanic eruption we know is due to occur there again.
Geothermal would also serve to make Hawaii and Iceland the world's leading exporters of hydrogen.