Why don't we use weights to store energy?

[bytebuster]

Q: Why don't we use weights to store energy?

One of the main reasons why we haven't switched to clean energy is the lack of efficient storage methods - But, why aren't we using dead weights to store energy and draw it back later when needed? As an example of what I mean:

A: Let's spin some numbers to further illustrate the poor energy density of gravity-based storage systems. Assume that you have a 100 kilogram lead weight that you can lower into a 10 meter deep hole in your yard.

Now, how much energy can it store? This is given by potential energy formula E=mgh, thus E=100kg⋅9.8m/s2⋅10m=9.8kJ≈2.7Wh.

For comparison, a single AA-sized battery stores about 2Wh of energy.

dotancohen: Does that imply that a single AA-sized battery with a suitable motor and gearing could lift four 25 KG suitcases to my third-floor apartment?
Luaan: Ignoring a few complications and efficiency losses, yup, almost.