5 - Hydroelectricity

Abstract

This chapter deals with the process of producing electricity from water. While historically this is one of the oldest methods of power generation, the topic has assumed increased importance in the context of renewed interest in renewable energy due to greenhouse gas (GHG) emissions, global warming, and depleting fossil fuels. Hydro energy is a major component of renewable energy-based power generation. Unit sizes of hydrogenerators vary widely from a few kW to a few hundred MW – technologies also differ accordingly. Unit sizes are based on size and power rating. Typical unit sizes are pico – a few kW, micro – hundreds of kW, mini – a few MW, and mega – hundreds of MW. Pico-, micro-, and minihydro plants are listed under small hydro while mega comes under large hydro. Small hydro plays an important role in remote areas, community development, and multipurpose infrastructure – applicable to both developed and developing countries. All large hydro units feed generated power to the grid, while small hydro may be grid fed or off-grid, standalone type. All minihydro plants feed power to the grid, while microhydro plants may be grid fed or off-grid type, and pico is always standalone. Large hydro involves the building of large dams with considerable civil works. They are not considered environmentally friendly due to large-scale deforestation and displacement of habitats. Further, they too cause GHG emissions. In comparison, small hydro is more sustainable as they need minimal civil works and cause little ecodisturbance.