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.
You could for example use black balls to reduce evaporation or power lines to places where you can store energy. You can also use batteries, electrolysis, huge flywheels, synthetic oil, molten salts or the sand itself.
I didn’t say I have the optimal solution, but in a desert you have very high temperatures heating up the concrete and sand and wind eroding it and clogging up the gears and pulleys. So it’s not optimal for the crane solution either.