XeonPony This one is actually storage. It uses concrete lifted by cables against gravity. Like clocks of old that used a chain weight to power the clock. I don't think it passes the "smell" test. Pumped storage of water works because of the height and mass of a lake of water. That much concrete would take up too much space. An amount that could be safely raised and lowered by a tower wouldn't last long enough to be practical. It's too easy to do. If it actually would work in a practical safe fashion it would already be done.
Somewhere we acquired two rolls of stainless steel cable, 1000 feet long. takes up about an 8 inch diameter spool 4 inches thick, safe working load probably 300 pounds, breaking strength on the order of 700-900 pounds. my folks live on the side of a gully/creek recently been classified as a salmon stream for which it isn't.
Anyhow, the sides of the creek are about a 45 degree slope. so we actually discussed getting 200 feet of angle iron and making a rail track up the side of the creek, and run the cable back and forth 10 times. could load the "train" with 4000 pounds of rocks. neglecting the losses.. could store all of a tenth of a kilowatt hour. practical power density/capacity, on the order of 15 minutes at 400 watts.
at 1 cent per trip worth of stored power, need to move up and down the hill about 100,000 times to pay back the investment, or 54 years at 5 trips per day.
