SEO-Group
History of the SEO
The history of SEO reflects economic and political developments in Luxembourg and the region. From the early plans for a pumped storage power station to
today, it shows how visionary ideas and (inter)national cooperation can create something significant.
Development of plans to use the river Our for energy generation. However, implementation fails due to the political framework conditions.
As part of the Marshall Plan, the use of the River Our for energy production is being reconsidered in order to improve Luxembourg’s economic situation after the Second World War.
Concrete project plans are drawn up with international participation. The construction of a pumped-storage power plant and the establishment of an operating company are approved.
Émile Mayrisch submits the first proposal for the construction of two dams in the Our Valley. Two years later, he co-founds ARBED.
On May 29, the Société Electrique de l’Our (SEO) is founded as a joint-stock company. The Luxembourg state and RWE later each acquire a 40.43% stake.
On July 10, the Grand Duchy of Luxembourg and the state of Rhineland-Palatinate sign a treaty, which remains the legal basis for the pumped-storage power plant to this day.
Construction begins. The large-scale project includes the construction of a dam, an upper reservoir, and an underground machine cavern.
The Moselle Treaty is signed between the Federal Republic of Germany, Luxembourg, and SEO. As a result, SEO commissions the Grevenmacher and Palzem run-of-river power plants in 1964.
On April 17, the power plant is officially inaugurated in the presence of Grand Duchess Charlotte—it is considered the largest pumped-storage power plant in the world at the time.
Commissioning of the first four machine units, each with a capacity of 100 MW. A year later, machines 5 to 9 follow.
Commissioning of machine 10 with a capacity of 200 MW—the most powerful pump turbine worldwide at the time.
Start of expansion work to install a tenth machine to meet Europe’s growing electricity demand.
Through its subsidiary CEDECEL France, SEO acquires four French Moselle power plants: Koenigsmacher, Liégeot, Pompey, and Uckange.
The new run-of-river power plant Schengen-Apach is commissioned. It is operated by Cefralux, a wholly owned SEO subsidiary.
Foundation of Soler, specializing in wind farms for renewable energy production. SEO holds a 50% stake.
Foundation stone laying ceremony for the expansion of the power plant to include an eleventh pump turbine with a capacity of 200 MW.
The new control room is put into operation. The previous facility remains available as a redundant system.
The expansion requires extensive structural measures, including the construction of a new intake and the elevation of the upper reservoir’s target level by one meter.
Excavation of a new cavern begins to house the eleventh machine. Subsequently, the main assembly of the pump turbine starts.
Official inauguration and commissioning of machine 11 by Grand Duke Henri and German President Joachim Gauck.