Here's how I like to look at the distribution of Gigafactories.
Imagine we are in an alternative world of light much like our own except that we use renewable energy and batteries for all our energy needs. So we've got about 1B vehicles with about 70 to 100 TWh of batteries in them, and we've got 6 TW of power generation capacity backed up with about 30 to 60 TWh of batteries. So on an annual basis to maintain this worlds energy system, we need to replace about 10% of these 100 to 160 TWh of batteries. Thus we need to produce about 13,000 GWh batteries this year. This is how much Gigafactory capacity our alternative world needs.
Ok, back to this present darkness, according to the 2016 BP energy review, total primary energy consumption was 13,147.3 million tonnes of oil equivalent (Mtoe). And can see how that consumption is distributed across the globe here (
http://www.bp.com/content/dam/bp/pdf/energy-economics/statistical-review-2016/bp-statistical-review-of-world-energy-2016-primary-energy.pdf).
So let's bridge from the world of light to this present darkness. We need about 1 GWh of annual Gigafactory capacity per Mtoe of current consumption, about 13,000 of each. Naturally, there are advantages to have much of this GF capacity close to where energy is consumed.
So here is what each region needs roughly:
China ....................................3000 GWh
Asia Pacific, excl. China .......2500 GWh
Europe & Eurasia .................2800 GWh
US ........................................2300 GWh
Americas, excl. US ..............1200 GWh
Middle East ...........................900 GWh
Africa .....................................450 GWh
Naturally some regions may be better suited for exporting by virtue of proximity to raw materials, abundant cheap solar and other renewable energy, infrastructure, trade agreements and other issues. The Americas, ME and Africa may prove to be exceptional exporters. Regions which must import lots of raw materials may do well to focus on recycling and import recyclables. Additionally some regions are growing faster than others, so this needs to be anticipated.
So I'd like to see our world grow into roughly this distribution of GF capacity by 2030. If Tesla wants to own say 10% of this market, then it will need 2 or 3 campuses in each of the top four regions, 1 or 2 in the Americas (excl. US) and the Middle East, and 1 in Africa. This is 11 to 15 campuses worldwide for Tesla.
The beauty of rolling out this 13,150 GWh capacity by 2030 is that this alternative world of light is will not lag too far behind. Sure, this is about a 130 fold increase in capacity over 14 years, but growing GF capacity at about 41.5% per year achieves this. Seven doublings in 14 years, and the dark age of oil will fade from sight.