So assume a near future world with 10 billion people with average standard of living and energy use that of the current US, which has 1/3 billion people. Total energy is 4500*10*30 TWh/year, which to one significant figure is 1000000 TWh/year.
In http://withouthotair.blogspot.com.au/2014/08/shale-gas-in-perspective.html we see:
|Shale gas pad||Wind farm||Solar park|
|(10 wells)||87 turbines,|
174 MW capacity
380 MW capacity
|Energy delivered over 25 years||9.5 TWh||9.5 TWh||9.5 TWh|
|Number of tall things||1 drilling rig||87 turbines||None|
|Height||26 m||100 m||2.5 m|
|Land area occupied by hardware, foundations, or access roads||2 ha||36 ha||308 ha|
|Land area of the whole facility||2 ha||1450 ha||924 ha|
|Area from which the facility can be seen||77 ha||5200-17,000 ha||924 ha|
|Truck movements||2900-20,000||7800||3800 (or 7600*)|
So these facilities deliver 9.5/25 TWh/year. About 0.4. So we'll need 2.5 million of them. So if we take the "land area of the whole facility" to be 1000ha for wind or solar we get 2.5 billion hectares total.
Now according to google the world land area is 15 billion hectares. So no problem, right?