I’ll note that aggregate system cost still benefits significantly from including wind and other non-solar sources of energy; having a mix of different intermittent sources (and some firm generation such as geothermal) means less storage is needed.

  • jol@discuss.tchncs.de
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    3 months ago

    Pumped hydro is great for taking advantage of the geography but it’s thousands of times less energy dense. There was this guy that made a pumped hydro water tank on his roof and by his calculations a cubic meter of water was equivalent to a AA battery. A professional damm might be a bit more efficient though.

    I’m looking forward to see more heat based storage, like molten salt, heated sand, or pumped geothermal.

    • sushibowl@feddit.nl
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      3 months ago

      There was this guy that made a pumped hydro water tank on his roof and by his calculations a cubic meter of water was equivalent to a AA battery.

      That sounds crazy. Let’s do some math. From what I can find, a double A battery contains about 10-14 kilojoules of energy. Let’s use 14 to be charitable.

      A cubic meter of water weighs about 1000kg. We know the formula for potential gravitational energy U = mgh. So if we used all the energy from the battery, we could lift the water:

      14000 = 1000 * 9.81 * h
      h = 14000 / (1000 * 9.81) ≈ 1.43 meters (4 feet 8 inches)
      

      That assumes 100% efficiency of course. Still, lifting a ton of water even two feet ain’t nothing to sneeze at. Batteries have a lot of energy.