Comment on Solar Photovoltaics with Battery Storage Cheaper than Conventional Power Plants
jol@discuss.tchncs.de 3 months agoPumped 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.
sushibowl@feddit.nl 3 months ago
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:
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.
jol@discuss.tchncs.de 3 months ago
Thank you for doing the math! I think this was the video of the fella doing his water tank battery: youtu.be/CMR9z9Xr8GM?si=go28fQ6DYXyW1GTi