ČEZ Is Testing a 1:13 Model Before It Builds Orlík's CZK 8bn Pumped Storage. On a World-First Turbine, the Laboratory Sets the Programme

I will say this plainly. The riskiest item on this project is a machine that does not exist yet. It has to pass a water tank in Blansko before anything is built on the Vltava.

On 1 September 2026 ČEZ began model tests on a reversible Francis turbine for the Orlík hydropower plant. Its contractor is Litostroj Engineering. Engineers are running a 1:13 scale model of the five-metre machine at Blansko. They are checking hydraulic performance, efficiency and operating stability before production starts. The conversion behind that test is worth CZK 8 billion, about EUR 330 million. ČEZ calls it the largest Czech hydropower project in three decades.

What ČEZ is actually building at Orlík

All four generating units at Orlík will be rebuilt. Total installed capacity stays at 364 MW. Two units keep conventional one-way operation at 95 MW each, or 190 MW combined. The other two become fully reversible at 87 MW each, or 174 MW of pumped storage.

The reversible pair will pump water from the lower Kamýk reservoir back into Orlík when the grid has surplus power. One full cycle stores up to 750 MWh. ČEZ puts that at the daily consumption of about 80,000 Czech households. The head between the two reservoirs is 70 metres.

Main works start in 2027 and the pumped storage plant is due in service in 2033. It becomes the country's fourth large pumped storage facility, after Dlouhé stráně, Dalešice and Štěchovice. The last one was built in the mid-1990s. ČEZ says Orlík lifts national pumped storage capacity by more than 12%. The conversion is staged so at least two of the four units run throughout.

Why a scale model sets the whole programme

ČEZ describes the conversion as a world first. An operating run-of-river station is being turned into a pumped storage plant while it keeps generating. Two Kaplan turbines are being replaced by reversible Francis units inside a concrete envelope finished more than sixty years ago. The fourth and final unit at Orlík entered service 63 years ago.

That combination removes the usual comfort of a reference machine. There is no fleet of identical units to price a performance guarantee against. Efficiency, cavitation behaviour and stability across both the pumping and generating range have to be proven before metal is cut. The 1:13 model in Blansko is where that proof happens.

Only a handful of hydraulic laboratories in the world can qualify a reversible pump-turbine. Blansko holds one of them. Wikov agreed to acquire the Litostroj group in 2024, which brought that laboratory inside the supplier. So the release date for manufacturing is set indoors, in a test rig. Every civil and electrical package sits downstream of it.

The price of four hours

Take the published numbers at face value. 174 MW against 750 MWh gives a duration of roughly 4.3 hours. On my own arithmetic, EUR 330 million across 750 MWh works out near EUR 440 per kWh of cycle energy.

Treat that as an upper bound. The same spend renews all four units, holds 364 MW of capacity and adds decades of life to the whole plant. Storage is one product of the investment among several. It arrives on a site where the reservoirs, the head and the grid connection already exist.

Lithium projects clear that headline number per kWh today. Their design life is measured in fifteen to twenty years, and the largest Czech battery systems are still counted in tens of megawatts. Orlík is a duration asset with a design life measured in decades. Duration is where European systems are getting short as solar output grows.

The consents that never had to be reopened

The reservoir belongs to the Vltava River Basin Authority. Its chief executive, Petr Kubala, said the conversion needs no major structural work on the dam. Operating water levels set in the plant's operating rules stay unchanged. No land has to be acquired, and recreation, navigation and fishing are unaffected.

That is the quiet reason the turbine dominates the schedule. On a greenfield pumped storage scheme, consent and land would run for years and would swallow the critical path. Here they were settled decades ago by the people who built the dam.

What to watch next

Three things decide whether 2033 holds. The first is the model result and the date manufacturing is released. The second is whether the staged outage plan really keeps two units earning through six years of work. The third is laboratory and workshop capacity across Europe, because every operator now studying a reversible retrofit will queue at the same few doors.

For contractors and suppliers, the qualification gate deserves as much attention as the tender itself. For sponsors and investors, the lesson is about sequencing. When the novel item is a single machine, the programme is only as firm as the test that proves it. No amount of progress on site can pull that date forward.