With enough renewable energy from the sun, there is very little we're constrained by

http://www.sandia.gov/~jytsao/Solar%20FAQs.pdf

"All together, the technical potentials can be estimated to be: Solar electricity: 89,000 TWc · (1-0.708) · (1-0.0345) · (0.3) = 7,500 TWc Solar fuels: 89,000 TWc · (1-0.708) · (1-0.0345) · (0.1) = 2,500 TWc Solar thermal: 89,000 TWc · (1-0.708) · (1-0.0345) · (0.225) = 5,600 TWc

These are huge potentials, dwarfing by many orders of magnitude those of the other."