The total installed capacity of hydro power plants in Slovenské elektrárne's portfolio is 1,653 MWe. This represents about 40% of the total installed capacity, which generates on average around 11% of the electricity produced by Slovenské elektrárne. To generate electricity, they utilise the hydropower potential of Slovak rivers, which is continuously regenerated and so represents an inexhaustible energy resource – on the contrary to fossil fuels.
Because of their very variable power output and operational flexibility, hydroelectric plants are capable to satisfy the swiftly changing demands in the daily-load diagram. They are suitable to cover the short time load variation in the power system. The hydro power plants located at large water reservoirs (e.g. Orava, Liptovská Mara, Nosice, Kráľová) and the pumped storage hydro-plants (e.g. Čierny Váh, Liptovská Mara, Ružín, Dobšiná) help us satisfy the non-uniform electricity consumption during the day.
Hydro power plants assure the following functions in the power system:
- satisfaction of abrupt variations in load
- frequency control
- stand-by power in case of failure
- reactive power production
Hydro power plants are suitable for frequency control and to create power reserve in a power system. They are also convenient as primary energy resource, i.e. they do not require any costly fuel to be purchased and imported. A hydroelectric power plant is usually erected as a product that shall satisfy numerous objectives. It is important not only for power generation, but also to provide additional functions, e.g.:
- water reservoir for the industry
- water reservoir for the agriculture
- protection against flood
- ship transportation
- holiday and sport resorts
The today's technology enables to utilise at hydroelectric power plants a generation process that is characteristic and specific only for the hydroelectric power plants:
- very effective transformation of primary energy to electricity
- high flexibility and manoeuvrability enabling to provide qualitative services for the power system
- environment friendly technology
- highly reliable operation and safety
- full automation of the whole process, possible operation with no operating staff and with remote control
- long life period of equipment and whole plant at inexhaustible primary energy resource
- low energy consumption
- compensation is possible in addition to the turbine and pumping mode.
The actually utilised potential of hydropower in the Slovak republic is about 57.5%.