For over 2,000 years, hydropower was the driving force behind agriculture and, in consequence, civilization. Used by the ancient Greeks for grinding grain, the energy derived from flowing water has been utilized by governments and communities across the world. Today, it is one of the most cost-effective means of generating electricity.

The basic principle of hydropower is using water to drive turbines. Hydropower plants are used with two basic configurations: dams and reservoirs, or without. Hydropower dams with a large reservoir can store water over short or long periods to meet peak demand. Hydropower without dams and reservoirs means producing at a small scale, typically from a facility designed to operate in a river without interfering with its flow. Small-scale micro hydropower projects can greatly impact communities in remote locations and are considered by many to be a more environmentally friendly option.