BBI Zeneris

Hydro energy – general information

The process of generating energy from water is similar to the process of generating energy from wind, as it is based on the same principle: kinetic energy of the flowing water is converted into mechanical energy which, when a generator is connected to a system, allows to produce electricity.

Nowadays there are several types of hydro power plants used. The most common include:

 

• Installations where dam is used to store water in a reservoir. Water released from the reservoir flows through a turbine, rotating it and producing electricity. Water can be released on request (e.g. in case of a sudden demand for electric energy) or can flow continuously;

• Installations using the energy of flowing rivers, the solution is most commonly used in the so-called Small Hydro Power Plants;

• Pumped-storage power stations. Most frequently they consist of two reservoirs: upper and lower. If there is no demand for power, the energy is stored by pumping water to the upper reservoir. When there is demand for power, water flowing from the upper reservoir to the bottom reservoir drives a turbine system.

Advantages of using water as a source of energy:

 

• It is a clean, renewable source of energy;

• It is a local source, increasing the power security of a country;

• Generally speaking it is available on request – the flow of water through the system can be controlled, and thus the production of electricity can be controlled;

• Hydro power plants are a source of additional benefits: e.g. power plants that are based on the dam/reservoir system can be used for recreation purposes (fishing, sailing) and the reservoirs can be used as storage reservoirs and supply drinking water.

Disadvantages of using water as a source of energy:

 

• The ecological balance in rivers can be disturbed, e.g. by reducing fish migration down the rivers (to the sea/ocean) and up the rivers (to spawn);

• Hydro power plants can also affect the quality and flow of water, creating areas of small oxygenation, which  has negative effect on river ecosystems;

• Hydro power plants are not capable of generating electricity during the periods of droughts.

History of using hydro power

The first documented use of hydro power dates back to 2000 BC. In the territory of the present Greece, there were water-mills used for grinding grains into flour. The hydro power was first used for the generation of electrical energy in the 19th century. In 1880, in the USA the first water dynamo was invented, which supplied power to 16 arc lamps. In 1881, in the town of Niagara power was supplied to street lamps from water-powered generators. The first hydro power plant was built in 1882 in the town of Appleton. By 1886, there were already 45 hydro power plants operating in the territory of the USA and Canada, three years later their number in the USA alone grew to 200. In 1907, hydro power plants produced 15% of total electricity generated in the USA. This share increased to 25% in 1925 and reached 40% in 1940. In 2003, the annual production of electrical energy by hydro power plants in the USA amounted to 18,000 MW.