Reading Time: 6 Minutes 22 Seconds
General info
Dlouhé stráně is a pumped-storage hydroelectric power plant situated in the Hrubý Jeseník mountains, in northern Moravia.
The construction started in 1978, but in 1980s the authorities suspended the project.
Between 1985 and 1989, work resumed following modernization and the power plant became operational in 1996.
The facility consists of two separate reservoirs, a lower basin and a higher one on top of the hill, connected by underground infrastructure.
The lower reservoir was created by a 56 m high dam on the Divoká Desná river at 824.7 m elevation.
It contains 3.4 millions m³ of water and undergoes water level fluctuations of up to 22.2 m during operation.
The upper reservoir stands at the summit of the Dlouhé stráně mountain at 1,350 m and stores 2.72 millions m³ of water, with levels varying by about 20 m depending on turbine activity.
The plant operates as an underground structure that includes turbines, transformers and other associated machinery.
Two feeders, each approximately 1.5 km long, connect the upper basin to the underground power plant, and two tailrace tunnels link the plant to the lower basin.
Functioning of the hydroelectric plant
The Dlouhé stráně power plant is called reversible or pumped-storage because it can operate in two opposite directions.
It pumps water from the lower reservoir into the upper one to store energy during periods of surplus (typically at night).
Subsequently, the plant switches to turbine mode during peak demand times to generate electricity by releasing water from the upper to the lower reservoir.
This dual-mode operation enables the plant to produce peak energy by converting surplus energy and also serves as a backup power source for the electrical system.
At its core, the facility houses 2 reversible Francis turbines located in an underground chamber.
Each turbine can generate up to 325 MW during generation mode and 312 MW when operating in pump mode, enabling the plant to both produce and store electrical energy according to grid demands.
Such capability allows the power plant to respond rapidly to real-time energy conditions and needs, maintaining system stability through dynamic frequency and voltage regulation.
Power transmission to the national grid occurs through 400 KV cable conductors that connect the underground facility to a switching station.
From this station, an outdoor transmission line extends for 52 kilometers through the valley terminating at the Krasíkov substation where the power integrates into the broader national transmission network.
The underground infrastructure of the Dlouhé stráně power plant extends beyond the turbine chamber into another section that includes three-phase transformers and switching equipment.
Other facilities include administrative offices with a control room, warehouses and garages, a converter station, a fire extinguishing room, water purification and waste water treatment systems.
Dlouhé stráně power plant diagram
The diagram here below highlights the main pieces of the plant:
– At the lowest level, in light blue, are the Francis turbines with their protective cover
– In fuchsia and red are the generators
– The beige rounded-shaped items on the highest underground floor are the upper parts of the TG1 and TG2 pony motors (TG = Turbine Generator), which are used to start the engine units in the pumping direction.
This is a very high-level overview of the main parts.
For a detailed exploration of each chamber and its related technical equipment, you can explore the virtual tour.
What to see in Dlouhé stráně
If you are interested in knowing more technical details about the power plant, you can join a physical tour.
The shortest tour includes a visit to the info centre, the underground chamber with the top of the 2 generators and the lower reservoir.
The longer route includes all of the above, plus a visit to the upper reservoir – they will leave you about 30 minutes to do the full walk around the basin.
There is also a so-called “professional tour” that provides access to more chambers of the plant and in-depth technical explanations.
At the info centre you are given a pair of virtual reality glasses and a headset for a presentation of the power plant, which is quite well done and interesting.
You can choose between Czech and English for the virtual experience, but other than that, everything else is conducted in Czech. English language tours are available only for groups with a minimum of 25 people.
Tours are somehow expensive and I would say that overall they are not worthy if you are not really into technicalities.
The cost is high, because each tour includes a dedicated bus that collects visitors at the meeting point in the the Kouty area and brings them to the specified locations. This bus service is needed, because the road to the plant is closed to traffic.
How to get there
If you are not interested in the power plant itself, you can skip the tour and get to the upper reservoir on your own either by bike or on foot.
- By bike:
It is a 16 km (one way) rewarding ride, which lets you see also the lower reservoir on the way.
Unfortunately, it is not possible to ride around the upper basin, everywhere there are signs to remind you of that. Nevertheless, you can still reach the top – refer to the “end” pinned point on the map linked above.
There is a small area of a few dozen metres where you can stand with your bike and take a great photo.
If you climb from other sides of the hill, access is available only by stairs (visible when zooming in the map) and you won’t be able to bring your bike in. - On foot, with two different options:
You can opt for the chairlift that from Kouty brings you to the top of Medvědí hora (the Bear mountain) and then walk for ~1 hour until the reservoir.
Or just walk the entire route for a beautiful full day hike – 12 km in total, with an elevation gain of 800 m.
When at the top, several people rent kick scooters to ride the long way downhill.
To reach Kouty nad Desnou you can jump on a train in Šumperk, Zábřech na Moravě or Olomouc.
By car, it is about 2 hours from Brno and almost the double from Prague.
