It's ~6000 Tesla Megapack stations [1], along with HVDC transmission lines (if we're upgrading transmission lines from AC->DC, drop those aerial lines underground while you're at it for reliability and to stave off the NIMBYs). I entirely appreciate the scale of the problem we're facing regarding energy storage (climate change keeps my up at night), hence my arguments for solutions available today, not those that might (might!) start producing power in a decade. You can buy these battery stations today (Tesla quotes a 3 month deployment cycle). You can recycle their battery cells today.
There are over 7,000 power plants in the United States run by over 3,000 companies. There are over 55,000 substations and over 450,000 miles of high-voltage transmission lines. I don't believe what I'm proposing is unreasonable. Hard? Sure. But unreasonable? Absolutely not. Going to the Moon was hard, and we still went to the Moon.
[1] https://www.tesla.com/blog/introducing-megapack-utility-scal...