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.
In most cases, you can even get water for free with rain and runoff. Pretty much no large-scale artificial lake is filled manually, they just dig a hole and wait.