Dlouhé stráně pumped-storage plant in Czechia has doubled output since 2013

The Dlouhé stráně pumped-storage hydropower plant in the Šumperk region has doubled its annual electricity output since 2013, to as much as 740 gigawatt-hours. This is partly due to its important role in balancing rising electricity generation from renewable sources, which places greater demands on stabilising the domestic power system. The plant’s annual output could now cover the consumption of approximately 200.000 households. Ludvík Štrobl, head of operations at the Dlouhé stráně pumped-storage plant, told CTK.

The Dlouhé stráně pumped-storage plant began operating in 1996 and has served as a giant energy-storage facility ever since. It plays a role in the power system both when surplus energy is used to pump water from the lower reservoir to the upper one and when energy is in short supply, with the plant generating electricity using its powerful turbines and selling it at a higher price.

“Output from the Dlouhé stráně pumped-storage plant began to rise in 2013. We can attribute this in part to greater use of renewable energy from solar and wind power plants,” Štrobl said.

According to Štrobl, the plant’s operating pattern has changed over the past thirty years. In its early years, surplus electricity was used for most of the year to pump water into the upper Dlouhé stráně reservoir at night, while the plant generated electricity during the day to meet higher demand from industry. Now, in the summer months, its powerful pumps move water into the upper reservoir during the day as well, when solar and wind power plants are operating.

“We can store around 3700 megawatt-hours of electricity in the form of water in the upper reservoir,” Štrobl said.

The Dlouhé stráně pumped-storage plant’s annual output is now roughly twice what it was in its first years of operation. Štrobl said generation could theoretically be even higher if the reservoirs were filled and drained more frequently. The upper reservoir, which holds 2,72 million cubic metres of water, can be emptied through two turbines in just under six hours, while refilling it takes 7,5 hours.

Last year, ČEZ Group completed a two-year, 840 million koruna modernisation of the Dlouhé stráně plant. Engineers focused mainly on refurbishing key components of the turbine-generator units, which have been in service for 30 years. According to Štrobl, the modernisation improved safety and extended the plant’s service life. Over the past two years, investment has also gone towards fire safety and a camera system monitoring the operation of the equipment and activity across the site.

The Dlouhé stráně pumped-storage plant played an important role during the floods two years ago, helping to regulate the flow of the Desná River. This unique energy facility attracts tourists to the mountain region; around 100.000 people visit the inside of the plant and the reservoir at the mountain summit, at an elevation of 1350 metres, each year. Thanks to regular investment in maintenance and the renewal of its technological equipment, the Dlouhé stráně pumped-storage plant could continue operating for many decades to come, Štrobl said.