SEO-Group
History
The evolution of SEO has been closely intertwined with the economic and political development of Luxembourg and the Greater Region. What began as an ambitious vision for a pumped‑storage power plant has, over the decades, matured into a project of international significance.
Today, SEO represents innovation, sustainable energy generation, and effective cross‑border cooperation. Its history shows how forward‑thinking ideas can grow into a milestone project that actively helps shape the energy future of an entire region.
Commissioning of the new control room; the previous facility remains available as a redundant system.
Ceremonial inauguration and commissioning of Machine 11 in the presence of Grand Duke Henri and German President Joachim Gauck.
Start of excavation for the new cavern housing the eleventh unit, followed by installation of the pump‑turbine.
Implementation of major expansion works, including the construction of a new intake and the elevation of the upper reservoir’s target water level by one metre.
Laying of the foundation stone for the eleventh pump‑turbine unit (200 MW).
Establishment of Soler to develop, promote, operate, and expand renewable energy production in Luxembourg.
Commissioning of the “Schengen–Apach” run‑of‑river power plant, operated by Cefralux, a subsidiary of SEO.
Acquisition of CEDECEL France and its four Moselle power plants: Koenigsmacher, Liégeot, Pompey, and Uckange.
Commissioning of Machine 10 (200 MW), at the time the most powerful pump‑turbine in the world.
Start of expansion works to install a tenth machine to meet the growing European electricity demand.
Official inauguration of the power plant—then the largest of its kind—attended by Grand Duchess Charlotte.
Commissioning of the first four machine units (100 MW each), followed by Machines 5 to 9 the following year.
Signing of the Moselle Treaty between Germany, Luxembourg, and SEO; commissioning of the Grevenmacher and Palzem run‑of‑river plants two years later.
Beginning of construction, including the dam, the upper reservoir, and the underground machine cavern.
Signing of the state treaty between Luxembourg and Rhineland‑Palatinate, forming the legal basis for today’s pumped‑storage facility.
Founding of the Société Electrique de l’Our (SEO) as a joint‑stock company; later, Luxembourg State and RWE each acquire a 40.43% share.
Founding of the Société Electrique de l’Our (SEO) as a joint‑stock company; later, Luxembourg State and RWE each acquire a 40.43% share.
Reassessment of the River Our’s hydropower potential under the Marshall Plan to support Luxembourg’s post‑war economic recovery.
Development of plans to harness the River Our for energy generation; implementation halted due to political constraints.
Émile Mayrisch presents the first proposal for constructing two dams in the Our Valley.