You forget Australia!Sage wrote:...Apart from Arizona and E Calif., our Arabian friends have a monopoly on sunshine, too!...
Anyway, even if it only could do a very unimpressive 100 watts per square meter at noon, a square kilometer solar collector would give 100 MW peak power. A solar array 100 kilometers on a side, which would hardly be noticed in the vastness of the American southwest, would generate 1000 GW of peak power.
I've tried to find the "efficiency" of splitting water into hydrogen and oxygen by electrolysis. The best answer I found is that it is very efficient. That is, if the reverse of the process - combining the hydrogen and oxygen back into water in a fuel cell, for instance - were 100 percent efficient, you'd get back most of the electrical energy used to make the hydrogen. As an energy storage cycle, electrolysis combined with fuel cells is about as efficient overall as any other way of storing energy. The problem is the well-known difficulties of storing hydrogen.
I read somewhere that methanol actually has more hydrogen per unit volume than liquid hydrogen. It is obviously much more practical to store. The missing link is how to make methanol, or any other easily stored compound of hydrogen, from sunlight and water vapor.