The concrete blocks are slowly hoisted upwards by motors powered with electricity from the Swiss power grid. As each block descends, the motors that lift the blocks start spinning in reverse, generating electricity that courses through the thick cables running down the side of the crane and onto the power grid. In the 30 seconds during which the blocks are descending, each one generates about one megawatt of electricity: enough to power roughly 1,000 homes.
Pumped energy storage can be done with just a pipe between two lakes, using natural elevation differences as the source of gravitational energy. Which would be a fraction of the concrete required for a dam or this crane thing, and would also largely be independent of the sizes of the lakes, so you can scale it up to an enormous capacity with not that much more concrete.