Study visit in Hydro power plant
The first concept of the Porąbka-Żar pumped-storage plant was devised already in 1952. This resulted from favourable geographical and hydrological conditions formed by the water reservoir in the Soła River, with capacity 28 hm3, created by the construction of Porąbka concrete gravity dam, and nearby Mount Żar, exceeding the water surface level in the reservoir by over 400 m. In 1979 the facility was commissioned as the second largest, in terms of its capacity, and the first underground pumped – storage power plant. The plant has four reversible Francis turbine units with turbine power 4 x 125 MW and pumps power 4 x 135 MW. The rotor diameter is 3.10 m. The static head is 440 m. The plant is capable of turbine operation for four hours, and pump operation for 5.5 hours. Its nominal discharge is 35 m3/s. The entire cycle’s efficiency is 75%. Power tunnels directing water and the whole power plant are inside the mountain. The plant’s average annual electricity production is 640 GWh, while energy consumption amounts to ca. 840 GWh. The upper reservoir was constructed as artificial atop Mount Żar. The reservoir’s bottom is completely paved with asphalt, and its capacity is ca. 500000 m3.
Firstly, a movie about hydropower plants in Porąbka, Tresna and especially Żar was shown. It gave a brief look at the technology and importance of such power plants in general energy system. Afterwards, we went to the technical rooms under the lake level, where it was possible to see all the machines and devices needed to produce energy from accumulated water in the upper reservoir. During our trip power plant works in generation mode producing 136 MW, while maximum possible power is 500 MW.
It was a very valuable experience to see the hydropower plant Porąbka-Żar, especially because it is the only hydropower plant that is planned to visit during our Clean Fossil and Alternative Fuels Energy programme so it is different than other trips. This visit helped also to illustrate the theoretical knowledge gained during classes and see the construction of the power plant from a practical point of view.
How CFAFE students can use the knowledge gained during the training in their future professional life?
During this visit, we found out how this type of power plants looks like in practice, how the operation of the power plant goes on which is useful knowledge for future graduates of Clean Fossil and Alternative Fuels Energy. What is more, the guide told about the meaning of power plant in the whole energy sector of the country, for example in case of blackouts, which could change our minds or support the opinion that hydropower plants are very important.
Authors: CFAFE students: Przemysław Dygas, Michał Rabiej