Hydro-power or water power is power derived from the energy of falling water and running water, which may be harnessed for useful purposes. Kinetic energy of flowing water (when it moves from higher potential to lower potential) rotates the blades/propellers of turbine, which rotates the axle. The kinetic energy of flowing water is converted to electrical energy.

Hydro-power is the most widely used form of renewable energy, accounting for 16 percent of global electricity generation – 3,427 terawatt-hours of electricity production in 2010, and is expected to increase about 3.1% each year for the next 25 years.

Advantages of Small Scale Hydro

• A high efficiency (70-90%), by far the best of all energy technologies
• A high capacity factor (typically >50%, compared with 10% for solar and 30% for wind
• Slow rate of change; the output power varies only gradually from day to day (not from minute to minute)
• A good correlation with demand i.e output is maximum in winter
• It uses a long-lasting and robust technology; systems can readily be
  engineered to last for 50 years or more