[elihu]

Let's see: it takes 9.8 joules to lift 1 kg by 1m. Let's say the tower is 100m high. The video says the blocks are 30 tons. 1 joule is 0.000278 watt hours.

9.8 * 30000 * 100 * 0.000278 * 0.0001 = 0.81732 kilowatt hours per 30 ton brick.

They claim they can store 100 mwh of energy. So, that's 100000 / 0.81732 = about 122,351 bricks.

From the top of the building it looks like it stores about 22x24 cubes per level, assuming the parts that aren't following the grid pattern are the lifts. So, 528 cubes per level. That would mean they need 231 levels of upper cube storage at an average height of 100 meters above the lower cube storage area, and it looks like they've only got about 29 total so far.

The math seems suspicious, but maybe my assumptions are wrong, or I made a calculation error. The structure might continue underground quite some distance, or the 30 ton cubes in the video aren't what they're using on the actual structure, or what looks like a single cube in the images are actually 8 or 27 cubes stacked into a bigger cube.

I'd be curious how this compares to the cost of LFP batteries, which are somewhere around $100 per kwh or so (in China). My guess is it's probably a lot more expensive than batteries or pumped hydroelectric storage.

[defrost]

Assuming your 278 factor is correct in value and scale (I didn't check)

9.8 * 30000 * 100 * 0.000278 * 0.0001 = 0.81732 kilowatt hours per 30 ton brick.

should(?) read

9.8 * 30000 * 100 * 0.000278 * 0.001 = 8.1732 kilowatt hours per 30 ton brick.

surely? 0.1 is a tenth, 0.01 is one hundreth, looks like you threw in an extra shift for luck.

> My guess is it's probably a lot more expensive than batteries or pumped hydroelectric storage.

Location, location, location!!

Not everywhere is suitable for pumped hydroelectric - relatively few places have dams or are dam suitable.

This at least fits in with modern city aesthetics and might be integrated and expanded to include dual use electric vehicle parking functionality ... (with vaguely interesting optimal usage algorithms).

[elihu]

Ah, so I did. 8.1 kwh per brick sounds like a more substantial amount of energy. They'd need about 12,235 bricks at a 100m height, which is closer to practical.

I'm still kind of skeptical. I mean, pumped hydroelectric storage is pretty cheap. It's hard to compete with that; but then maybe there are uses for a big gravity battery in a dense urban area where hydroelectric isn't an option and maybe even batteries are a potential public health and safety risk. Maybe I've spent too much time alternating between Kicad and Factorio lately, but the concept of plopping down a bypass capacitor the size of a large building to buffer out "noise" on your power grid seems kind of like a normal thing to do.

[realusername]

> Not everywhere is suitable for pumped hydroelectric - relatively few places have dams or are dam suitable.

Sure but one of the prototypes was based in Switzerland... probably one of the best place on earth for dams.

[defrost]

Yeah, thing about Switzerland is that a lot of global companies are based there and market products and services globally that aren't swiss clocks, chocolates, dams in the alps, lederhosen, etc.

This particular company has multiple gravity battery designs that it's shopping globally and building the first industrial scale installation in China (checks map) some distance from Switzerland.

So, again, not everywhere is suitable for pumped hydroelectric and (obviously one would have hoped) it's okay to develop products for places that have no dams while living in a place that has dams.

Do you have a point to make?