Hydro power is one of the oldest sources of energy known to man, based on the extraction of kinetic energy from flowing water. This is achieved by means of a turbine, whose rotational movement is transferred through an axle towards an electric generation. Until the mid 20th century, hydro was the main source of energy for large scale power production.
Small hydro units are those that have an installed power capacity below 10MW. This renewable technology has low environmental impacts, and scores the lowest impacts in Life Cycle Analysis (LCA) amongst power production technologies.
Small hydro (according to the United Nations Development Agency) may be classified as:
- Nano or Pico centrals: Installations whose installed power is below 1kW. Mainly used for single-family power generation or mechanical work
- Micro centrals: Facilities with installed power ranging from 1 to 100kW. They have found applicability in supplying power to isolated sommunity grids
- Mini Centrals: Are those that have an installed capacity from 100 to 1000kW. They are used to supply power to a number of communities as well as electrification of the national grid
- Small Centrals: They have an installed capacity from 1 to 5MW. Used to supply power to small cities and suburbs, as well as electrification of the national grid
Energy sourced from small hydro has a highly competitive price, excellent project lifetimes and reliability when compared to other renewables. This is mainly due to the fact that small hydro has been developed for over a century, with Capacity Factors (CF) above 50% and investment costs of around US$ 2 million per installed MW achievable with present day technology.