>>13614586there are many sophisticated vacuum/magnetic high pressure flywheels including those used by NASA
there is no such thing as infinite storage, these materials reach a limit of structural integrity, most importantly to the centripetal forces although there's also electrical challenges when you convert out
"can store the output of the entire USA in one year" - build it, or even just show your calculations
btw the output of the USA 1 year is not a fixed amount
biggest project of this nature there is I believe is still the one in Minto, Ontario
http://nrstor.com/portfolio/ - it's 10 high capacity flywheels
if you think you have something better than that or the NASA G2 flywheel, by all means build it
https://www.researchgate.net/figure/NASA-GRC-G2-Flywheel-module-cross-section_fig1_242194194existing ones have a similar value proposition in terms of cost and maintenance to batteries
