Humans have used water power to supply energy for almost as long as we have used wind power. Archaeologists have discovered descriptions of water wheels used for grinding grain that date back to more than 3,000 years ago. Toda, the energy of falling water is used mainly to drive electrical generators at hydroelectric dams. As long as snow and rainfall can fill the steams and rivers, moving water can be a renewable source of energy.
Though large hydel power is a largely practiced day-to-day affair in any modern society, exploitation of hydel energy in miniature form termed as microhydel is a comparatively recent addition for its low initial cost, low environmental impact etc.