I recently saw this question and I immediately thought that the discussion was too limited to current energy production, it simply assumes that the amount of energy we use today is the amount of energy we currently need. But the biggest part of the world population live in countries that do not produce enough energy to cover their demand.
So I was wondering how big should be a solar panel array in order to supply the world energy needs. But I guess that first one should determine what could be the energy need compared to the current production. Predicting real energy need, by the time the solar array would be ready, I think is impossible because it should take into account technological changes population growth and additional demands like desalination due to the exhaustion of fresh water. But at least a rough estimate could be made on the hypothesis of no population growth and simply the developing countries aligning to the developed ones. I saw this list which gives an idea of how skewed is the production. So my question now is:
if the developing countries want to reach a per capita energy consumption similar to that of China, which seems reasonable, how much the current energy consumption would grow?