Gravity based with weights is generally considered not cost effective; others already did the math that your 100 ton proposal can still only store a fraction of what a consumer grade battery pack can do, but on top of inefficiency there's space and maintenance requirements. It works in situations where e.g. trains go uphill empty and full downhill, but generally it doesn't work.

Water based systems work better because water is easy to move, plentiful, and there's natural basins to pump into / flow out of that can contain billions of liters.