Ledvice – Not only from coal, but also from water the Ledvice Power Plant produces electricity. While in the first case the electricity produced goes mainly to the transmission system, in the second case it serves only the needs of the power plant. In particular, it is used to light the area of the wastewater treatment plant, where four PROTUR bladeless roll-off turbines are installed in retention tanks, through which environmentally friendly water is returned to nature. The ČEZ Group has chosen the Ledvice Power Plant as its cornerstone, so these unique mini-turbines could appear elsewhere in time. “The principle of the rolling turbine was invented at the end of the 20th century by Associate Professor Miroslav Sedláček from the Faculty of Civil Engineering at the Czech Technical University in Prague. Other experts then took up its technical improvement. The main advantage of the turbine is its ability to operate at extremely low gradients from 0.4 to 1.5 metres with different water flows. In practice, it is a decentralised, environmentally friendly source of renewable energy for rural areas. In the case of the CEZ Group, we used an overflow in retention basins for installation, where treated water is returned to nature. Similarly, it is installed in the outlet channel of the wastewater treatment plant in Žďár nad Sázavou. However, it can also function in the cooling tower circuit or at outlets used to stabilise the levels of ponds and reservoirs. The applications are really diverse, for example on a stream flowing through the garden of a family house,” says Petr Frydrych from PROTUR Turbine (Precession ROlling TURbine).
The main advantage of the PROTUR system is its ability to work efficiently with low water flows and small terrain gradients. For example, with a rotor diameter of 0.6 m and a gradient of 1 m and a flow rate of 100 l/s, the turbine has a power output of 0.5 kW. The daily production is therefore 12 kWh of electricity. If four machines are connected to one system with a power output of 10 kWh per day, they will produce up to 3.7 MGW of electricity per year. This is slightly more than a household consumes in a year. Four such turbines are now installed at the Ledvice Power Plant. They also include a battery storage of 12 kWh capacity. In the search for the optimal application of the turbines, it was chosen to place them at the outflow of the safety tanks of the wastewater disposal technology, so that the residual energy potential of the treated wastewater leaving the power plant is used. In addition, the turbines have sufficient power to make the entire area of the technology a balance of energy self-sufficient section. “The gradient of the water flowing out of the retention tanks is 80 cm, which is almost ideal for this type of turbine. The energy produced is sufficient to power the lighting and operation of the wastewater treatment plant. However, unlike other environmental projects we have already implemented in the past and are planning for the future, this is only a minor contribution to the environment.
Rather, it is rather a stepping stone whether the turbines can be used in water management in other locations of the CEZ Group. In sum, it may one day be a non-negligible ecological renewable energy source,” said Miroslav Svoboda, Director of the Ledvice Power Plant, adding that the rolling turbines have been in smooth operation since February this year. Marian Piecha, the Deputy Minister of Industry and Trade, sees huge potential in wind turbines. “I know Associate Professor Sedláček and it is amazing that he has managed to turn the rolling principle, a physical quantity that cannot even be described mathematically, into such a useful thing. It is certainly one of the ways to decentralise power generation, even if it is only applicable on a smaller scale, for example for houses built near smaller watercourses. Of course, turbines are also of practical use in similar cases, such as here at the Ledvice Power Plant. It is commendable that a coal-fired power plant in particular uses not only coal but also renewable sources to generate electricity,” he said during his recent visit to the Ledvice Power Plant. Of course, he came in order to get personally acquainted with the principle and functionality of the wind turbines in real operation.
Author. Ota Schnepp, ČEZ Group: https://www.cez.cz/cs/pro-media/tiskove-zpravy/elektrarna-ledvice-se-zaradila-i-mezi-obnovitelne-zdroje-energie-stalo-se-tak-diky-pricineni-ctyr-vodnich-odvalovacich-turbin-88165
