I calculate a rather better figure for the Empire State Building: 365000 tons × 9.81 m/s2 × 1 m = 1 MWh which ought to at least be enough to provide short ter

I calculate a rather better figure for the Empire State Building: 365000 tons × 9.81 m/s2 × 1 m = 1 MWh which ought to at least be enough to provide short term backup power to the whole building.