Hydropower contributes one-fifth of the world’s power generation, and provides the majority of supply in 55 countries. For several countries, hydropower is the only domestic energy resource. Its present role in electricity generation is substantially greater than any other renewable technology, and the remaining potential, especially in the less developed countries, is vast.

Hydropower can be developed on a wide range of scales to meet diverse needs and market conditions. Small-scale, decentralized development has been responsible for bringing light and power to remote and rural communities throughout the world. Larger hydropower schemes feed the regional grid systems, substantially reducing the combustion of coal, which is the predominant power supply source.