Potential energy of 25000kg at height of 16 m is roughly 1kWh. At least in Earth's gravity. Same energy can be stored in small box of 100 regular li-ion cells.

What goes down must come up! The weight must be pulled up by energy input, therefor the unit is out of use while this happens. Two shafts would seem to be necessary. I have other ideas, which I cannot divulge, so I will say no more!

I used 25000kg @ 16m with a m/s of 9.81 (earths gravity) and got 3924000 Joules which is 1.09 kWh. I just used calculators I found on Google but I got the same result as @Pio Tr. Can anyone shed light on how gravitricity came up with 250 kW or fix my math/info?

@Pio Tr
1kWh seems low Have you allowed for the x 3600 to convert kW/s to kWh? SI units are per second
(1 joule = 1 Watt for 1 second)

This was made for imperial units - fitting that it takes place in Scotland ( James Watt defined horse power)
25000 KG = 55000 lb
to lift 550 lb 1 ft in 1 sec takes 1 hp
Shaft is 50 ft deep
Each weight can generate 100 HP (55000/550 ) for 50 seconds
.75 KW per HP = 75KW per weight (for 50 seconds)
2 weights
150 KW total for 50 seconds
If they drop it faster they can generate more power but over less time
I would be interested to see what the efficiency turns out to be.

Hmmm.....I got an idea, let nature store up energy for in the form of a liquid, maybe water, and then release it through a device tied to a generator. You could call it hydropower. You could also use wind and solar to pump the water back up again - but I think somebody already beat me to this idea.

There is no doubt that it should work but I would question the 80-90% efficiency.

This is not new,but other gravity systems would be cheaper to build,as they use towers to support their weights rather than digging a shaft if an old mine is not available. Of course,I assume erecting towers is cheaper than digging a shaft.

It’s just a demonstrator, 250 kW is probably just for 15 seconds. Where space is not a premium, this will scale better than lithium batteries and lasts longer too.

The Eiffel tower has been doing this for more than a century; except that they use water to power all the lifts in the tower. So what is new?