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What do hexbears think about pumped hydropower storage?
(hexbear.net)
To make solar power viable, we need a solution for overnight energy storage.
Batteries are complicated.
Do you know what isn't? Water go up. 
Recent forays into trying to do more pumped hydro in the US: https://www.hydroreview.com/hydro-industry-news/pumped-storage-hydro/alabama-power-files-with-ferc-to-surrender-chandler-mountain-pumped-storage-permit/