More specifically how was the problem of intermittent power solved? I'm not aware of any grid-scale solution to this problem unless you include vast amounts of hydro to provide power when there is no wind or no sun or both.
I looked up the McKenzie report[1] where I think the 5.7 trillion comes from. In short, the renewable energy would be 1.5 trillion, and batteries 2.5 trillion (transmission is the rest). If you have 50% hydro, then you don't need batteries, so the cost for the US would drop by 2.5trillion. Having hydro is a big reason why some countries can do it easier than others. It's not a white and black situation, after-all, the US is already investing a lot in renewable energy.
Second, the report says it provisioned for 900 "gigawatts" of batteries. If they mean GW rather than GWh (Which I think they do), that is not nearly enough, that is just 2000 GWh at today's prices. The US needs 500GWh on average each hour, so you only get batteries for 4 hours. You need to either build much more PV, or buy many more batteries. Also, 2000GWh is about 2 years worth of current global battery manufacturing. It's just not the same building out a small country or a large country electrical grid.
https://e360.yale.edu/digest/shifting-u-s-to-100-percent-ren...
That being said, it will happen, we'll soon switch to PV production, and it will happen faster than people think. It will be a disruption previously only seen in software. By 2030 we'll probably be pretty much powered by PV panels.
Transitioning the US to 100% clean power would cost - at most - $5.7 trillion.
We spent $8 trillion fucking up the middle east for oil.
Think about that - take all the time you need. Because if you still think this is about hydro access, and not leadership, you're holding up the change that is necessary.