We could bust water into hydrogen for a billion years and the sun's energy input to the planet would not be depleted one jot in consequence. We could bust water Into hydrogen (then burn the hydrogen) for a billion years and the planet would show no sign of drying up in consequence. For the purpose I referred to, in practical terms there is an unlimited supply of both solar energy and water. I don't mind wasting time typing this as long as you don't mind being accused of acting thick.