The mechanical energy of water (often mistakenly referred to as a hydro, with the corresponding factory) due to the sun.
The water found in lakes, rivers and sea absorbs electromagnetic radiation from the sun reaches the earth and evaporated. Ascending air currents raise the water vapor in the upper atmosphere. There the temperature is low and the steam condenses and turns into droplets. Many droplets together form the clouds that move with the wind. The droplets collide with each other merge and grow. Eventually as weighing heavily, falling to the ground usually in the form of rain.
The same mechanism (absorption of electromagnetic radiation and evaporation) due to drying clothes or our hair.
Caution: The water is a source of energy, not energy.