I did a bit of scratch math with the notion this might be more suited for individual, home power storage rather than grid supply - You need something in the order of a 5m tall tower bearing 73 tonnes to store 1 kilowatt hour (even then, ignoring conversion losses). So that's the weight of ~ten class-4 fully laden heavy trucks.
Once you can get it up in the air then the higher you can go you're doubling your storage in a linear fashion. Hoist one of those trucks to 50 meters (perhaps you have a handy cliff in your backyard) and you've stored as much as the ten trucks did at 5 meters.
So yeah scale seems hard, but the low technology/materials requirements and potential for gradual scale-up make this worthy of deep investigation. I think there's a lot of wandering off into dead-ends as far as limitations go though - Solutions that depend on a lot of concrete pouring, for example, are a no-go if the end goal is reducing atmospheric carbon.
Yes, but only once. This is energy storage not energy source for the purpose of human utility. The ability to pull that 1kw of potential energy back up (with some renewable source eg wind turbine) to be output over again is where the comparison breaks down.
A fairer comparison is current battery tech, you can pack something like 40kwh in 200kg of batteries (rough guess based on leaf ev battery modules). So vastly more in the same space/weight. But those are complex and energy intensive to manufacture, and have limited lifespans before further energy investment is required to recycle/replace them. The relative simplicity and long lifespan of gravity storage seems like it has potential. Not to mention the potential for owner/operator to self install, which could be great for developing nations.
Absolutely, useful just to illustrate the scale we're talking about for a given amount of energy stored as a real-world analog easy to recall.
Assuming you used cast iron as weights that has a density of ~7800kg/m³ at regular temperatures, so you're looking at about 10 cubic meters for that 1kWh of potential energy storage using an abundantly available, non-toxic material that will endure.
I can imagine this tech all packed up in a standard 40ft shipping container and dropped on premise.
This would be rather simple tech, that can supplement solar and wind on your farm, lodge, campsite or island. Another piece in the puzzle for smaller scale independence.
Not to replace metropolis-scale energy demands, as grandparent implies, but to smooth out fluctuations on hourly, household scale.
I imagine chemical batteries would be easier to ship and install, and require less maintenance. I really can't imagine any mechanical system that involves plugging and unplugging a load (or anything more complex than that) to be useful at small scales.
There will be a maximum drop rate that is supported by the machinery being built, and it seems reasonable, though not mandatory, that a 5x weight system will be designed to handle more generation than whatever it's 5x of.
Once you can get it up in the air then the higher you can go you're doubling your storage in a linear fashion. Hoist one of those trucks to 50 meters (perhaps you have a handy cliff in your backyard) and you've stored as much as the ten trucks did at 5 meters.
So yeah scale seems hard, but the low technology/materials requirements and potential for gradual scale-up make this worthy of deep investigation. I think there's a lot of wandering off into dead-ends as far as limitations go though - Solutions that depend on a lot of concrete pouring, for example, are a no-go if the end goal is reducing atmospheric carbon.