> Batteries are not a source of energy. They store energy. (You'd be surprised at how many people don't grasp that.) Talking about how many batteries we need to power the world without talking about where that energy is coming from is silly.

I'm not sure why you got such a weird impression. In his talk he clearly states that the power would be coming from solar energy. He even explained how much space you'd need for solar arrays and batteries if you want to provide the entire United States with power day and night (the biggest need for batteries).

He also mentioned there is utility for the battery to be used with your powergrid but the big win is using it with solar energy.

Not a direct reply, but to put some scale around the numbers:

20,000,000,000,000 kWh = 20,000,000,000 MWh = 20,000,000 GWh / 8,760 hours/year ~= 2,283 GW average steady-state generation, globally.

A typical utility-scale nuclear reactor produces around 0.5 GW.

Right, that one pixel was 2B powerpack. Solar Panels are quite larger than powerpacks, but that still looks like a large number to me.