Let's do back of the envelope calculations:
Great Pyramid of Giza weights 500.000 tonnes. It is 146 meter high. It's center of gravity is at 1/4 of it's hight, 36m. It's potential energy is about 50 MWh.
These guys claim that they can store 35MWh in their tower. Basically claiming that they can build the pyramid in a day and take it apart at night.
A pyramid has an centre of gravity which is intentionally low. This is evidenced by it only being at a quarter height. I'm not saying there aren't issues with the technology, but it's not the best example.
I just wanted to palce the claim into context. To give it some scale. This is also what I've found:
"San Francisco use about 6,500 MWh daily with around 800,0000 residents."
So assuming that it is to store solar power, you would need to build 100 towers to make it through the night. And it has so many moving parts, that make it really unreliable.
I think the clear way to store energy is Power to gas (LNG). The round trip efficiency is not that great at the moment, at around 75%, but that is not important*. Storing gas is a solved problem. 1 cubic meter of LNG is about 600 cubic meter of natural gas, about 6000KWh. In a 30 foot container that is about 200MWh, or 8 of these towers. The entire concept is just silly if you compare it.
This is 135000 cubic meter, or about 810000 MWh, enough to power the SF for 4 months.
*What is important is the total system cost. If you spend 2 EUR (including amortization) storing 1 EUR worth of electricity, you are doing it wrong**. What matters is the electricity cost at night. You can overcome efficiency problem with "just" more solar power.
** That is why the ie powerwall is a futile concept. It costs more to store the electricity than to buy it.