This came up a long time ago. It doesn't work well, the amount energy it stores is simply too low. I've seen a calculation somewhere, but it's too late here so

This came up a long time ago. It doesn't work well, the amount energy it stores is simply too low. I've seen a calculation somewhere, but it's too late here so can't reproduce - does anyone remember? Edit: here it is. https://news.ycombinator.com/item?id=6739349 https://news.ycombinator.com/item?id=6739349