few things:

I don't believe there is a "dark side" of the moon. There is a "far side", but the backside of the moon sees the light of day, too. The rotational period of the moon is almost exactly that of the orbital period it around the earth.

Second, I think the most efficient means of producing hydrogen was the electrolysis of water. Either solar or nuke makes it cheapest. Even if we burn coal, if you do it on a grand scale, there's more efficiency than on the small scale (think power plant vs. home heater)

Lastly, I think the most efficient use of hydrogen is the hydrogen cell, not combusting it. Too bsd that the current technology on hydrogen cells is not where it needs to be (cost or reliability) for general consumer use.