Excursion to the Dlouhé stráně Pumped Storage Power Plant

We started from České Budějovice at 5 a.m. by bus, which had to meet the EURO 3 standard to enter the protected landscape area. The journey to the largest Central European power plant of its kind took a full six hours, but we were rewarded with a truly remarkable experience.

The Dlouhé stráně Power Plant is located in the Hrubý Jeseník Mountains at an altitude of 1350 m. Interestingly, this power plant consumes more electricity than it produces. Despite this, it is still in operation and is completely irreplaceable for the power system in the Czech Republic, especially in recent times. The plant has two reservoirs - a lower and an upper one. The lower reservoir, located at an altitude of 825 m, is full of fish, but it cannot be fished. The upper reservoir is built at an altitude of 1350 m and visitors can enjoy the surrounding nature from there. In the summer season, it is possible to rent a scooter here and ride down from the top almost to the site, where the power station's engine room is located underground (the height difference is 525 metres).

The tour of the power plant started in the lecture hall with a short film, from which we learned how much the Dlouhé stráně power plant is needed for the power grid. In fact, it can draw energy from the grid in times of power surplus and store it in the potential energy of the water it draws from the lower reservoir into the upper reservoir, built by draining the top of the mountain. In contrast, when energy is scarce (for example, when clouds prevent the use of solar power), the water begins to flow downwards and its positional energy is converted into the necessary and quickly available electricity. This turns cheap energy into energy that can be sold quickly in times of scarcity (in the words of the guide, cheap energy is used to produce expensive energy).

After a short introduction, we were given helmets and went into the deep underground hiding the power plant's engine room with two turbine units. At the time of our arrival, one of them had just finished filming. The heat generated in the generator was omnipresent and we could partly feel how much energy was hidden in the tank. We could also see the train tracks underground where the transformers come in.

After inspection of the set and other mechanisms (man-sized ball valve used to shut off the water supply from the upper tank - at pressures greater than 50 atmospheres; pressure vessel

with compressed air designed for quick shutdown of the unit in case of de-phasing or disconnection of the power plant from the grid, etc.) we came out from underground, got on the bus and drove around the lower tank to the upper tank. On the way we had the opportunity to hear how the construction of the power plant was going. We learned, for example, that the construction of the power station remained almost unfinished, as a few days before the completion of the construction there was an accident in which the rotor - due to a small shift of the bedrock - met the stator at full speed. The damage was in the hundreds of millions, but only one reminder of the accident remains to this day - the ceiling underground is a different colour in one place.

We returned to České Budějovice at 20:00. Everyone enjoyed the excursion very much.