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Some key insights from the article:
Basically, what they did was to look at how much batteries would be needed in a given area to provide constant power supply at least 97% of the time, and the calculate the costs of that solar+battery setup compared to coal and nuclear.
Brother, with some luck a nuclear plant is in construction stage after those 20 years
China has been doing them in around 7 years from groundbreaking to grid connection and is trying to get that down to 5 years with their bailong power plant as they are developing an experienced work force and actually have experience making the parts