I’m pretty skeptical about this- wouldn’t a 30m sphere be incredibly buoyant when empty? I get its concrete, but it’s displacing huge amounts of water. So you’d need some massive anchoring, maybe that’s not a big deal. Second, I don’t know what depths we’re talking about here, but I feel like the stress from cycling these things daily would be insane- in high pressure salt water no less. I also wonder what the efficiency of this system would be compared to other similar batteries, like pumped hydro storage. It seems to me pumping out water to near vacuum while under crushing outside water pressure would be a significant power hog.
… you’d need some massive …
from the srticle :
… a sphere nine metres in diameter and weighing 400 tonnes will be submerged …
Can you calculate the weight of a sphere of 9 m of displaced water ?
No ? Well, it is 382 tons.
So, the concrete sphere is already massive by itself. “You” don’t need any complicated anchoring.
Same goes with the rest of your mechanical engineering intuitions : you did not work in this domain or study it, did you 😆 ?
Also, stress cycling is bad on most material, yes. But here it is compressive stress and the geometry is symmetric. Without further study, i want to believe this thing has good potential and my intuitions tells me it looks nice. Time will tell 😁 !
Thanks for the insight, I’m not a mechanical engineer, I’m a software engineer :) The walls on these spheres have got to be pretty thick- 400 tonnes is no joke. 3/4 of a meter if I had to guess.
Perfect guess ! (afaik)
ρ(concrete) ≈ 2.5 tons/m³
so full sphere ≈ (2.5 x 382) tons = 955 tons
they have 400 t so the cavity removes :
955 - 400 = 555 t … so 7.51m diam. cavity
… so, yes 3/4m thick wall 😌👍 !
I’m pretty skeptical about this- wouldn’t a 30m sphere be incredibly buoyant when empty? I get its concrete, but it’s displacing huge amounts of water. So you’d need some massive anchoring, maybe that’s not a big deal. Second, I don’t know what depths we’re talking about here, but I feel like the stress from cycling these things daily would be insane- in high pressure salt water no less. I also wonder what the efficiency of this system would be compared to other similar batteries, like pumped hydro storage. It seems to me pumping out water to near vacuum while under crushing outside water pressure would be a significant power hog.
Can you calculate the weight of a sphere of 9 m of displaced water ?
No ? Well, it is 382 tons.
So, the concrete sphere is already massive by itself. “You” don’t need any complicated anchoring.
Same goes with the rest of your mechanical engineering intuitions : you did not work in this domain or study it, did you 😆 ?
Also, stress cycling is bad on most material, yes. But here it is compressive stress and the geometry is symmetric. Without further study, i want to believe this thing has good potential and my intuitions tells me it looks nice. Time will tell 😁 !
Thanks for the insight, I’m not a mechanical engineer, I’m a software engineer :) The walls on these spheres have got to be pretty thick- 400 tonnes is no joke. 3/4 of a meter if I had to guess.
Perfect guess ! (afaik) ρ(concrete) ≈ 2.5 tons/m³
so full sphere ≈ (2.5 x 382) tons = 955 tons
they have 400 t so the cavity removes :
955 - 400 = 555 t … so 7.51m diam. cavity
… so, yes 3/4m thick wall 😌👍 !
That’s exactly the way I would have calculated it, glad someone beat me to it though. Thanks!