[einpoklum]

1. The energy overhead seems quite significant - as the concrete barrels don't really drop. 2. What guarantees non-collapse in case of winds (and ignoring floods)? 3. Does this really scale? I mean, concrete is more dense than water, but I think it's only... what, twice the density?

[666lumberjack]

Not the person you responded to, but you correctly identified some of the serious flaws in this idea. They claim to be using commercially available crane technology, but existing cranes are generally not designed to operate in high winds, so they seem like a poor match for wind energy. According to [0] tower cranes are typically limited to operating in wind speeds of 20m/s or less, where as wind turbines[1] top out at ~35m/s. That would mean when the turbines are at peak production (i.e, when you want to be 'charging' your storage) wind speeds would be too high for co-located concrete block storage to work.

The design also seems to have quite poor power density; their website[2] shows a single tower in front of fields of turbines, but they only quote a power output of 4-8MW - the equivalent of 1-2 large turbines - so in reality you'd need dozens of them for a single installation.

[0] https://www.cranes.org.nz/uploads/2/0/5/7/20572552/wind4.pdf [1] https://www.enercon.de/fileadmin/Redakteur/Medien-Portal/bro... [2] https://energyvault.com/