Post Aocv4eUDQycnIsSGwq by quokka1@mastodon.au
 (DIR) More posts by quokka1@mastodon.au
 (DIR) Post #Aocv4eUDQycnIsSGwq by quokka1@mastodon.au
       2024-12-02T04:52:54Z
       
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       @ewen i wonder if, with my simplistic understanding of power grids. the idea of using the excess to pump water uphill for later power-generating descent is in any way practical or helpful. Would certainly surprise some fish.
       
 (DIR) Post #Aocv4g4PXtAiDQOh0K by stfn@fosstodon.org
       2024-12-02T06:26:20Z
       
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       @quokka1 @ewen it has been done for the last hundred years https://en.m.wikipedia.org/wiki/Pumped-storage_hydroelectricity
       
 (DIR) Post #Aocv96D4Iiu2RcYTXU by stib@aus.social
       2024-12-02T04:58:02Z
       
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       @ewen I was interested to do a back-of-the-envelope estimate.Say we make the weights out of something relatively cheap like concrete. 1 cubic meter of GP concrete weighs about 2.3 tonnes. To lift 1kg up 1m takes 9.8 Joules, so to lift 2,300kg up two storeys (say, 10m) is 225,553J which looks like a lot, but works out to 62 Watt hours. So it would take a lump of concrete the size of a bar fridge being hoisted a couple of storeys to run, say a bar fridge for an hour.I think that might be why it's not being investigated as an energy storage medium for domestic use.
       
 (DIR) Post #Aocv97pkGPR1TresSm by wall0159@aus.social
       2024-12-02T05:15:58Z
       
       0 likes, 1 repeats
       
       @stib is totally right, sadly. For gravity storage of energy, you need a lot of mass (like a dam full of water) and 50 - 100m of elevation change ("pumped hydro")Some interesting work has been done with high speed flywheels (at 100000s rpms), but I think not for home storage (more for grid-level stabilisation). Also, you really don't want it to break at speed! ;-)@ewen
       
 (DIR) Post #Aocv99GivabpvpHw9Y by stib@aus.social
       2024-12-02T05:24:26Z
       
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       @ewen If you used steel it would be about 7,800kg, or lead 11,340kg, so the energy density would be three to five times higher, though more expensive to buy. And of course lifting any large weight is going to be a non-trivial engineering issue; and the higher the energy stored the greater the demands on the building. Not an engineer, but I'd reckon yeeting a dozen tonnes up a stairwell would probably require structural strength that couldn't be retro-fitted into an existing structure.