Actemium will be taking up the challenge to renovate 24 generators at the tidal power plant without stopping production. The project will be carried out in three stages.

The Rance tidal power plant near Saint Malo in Brittany, inaugurated by Charles de Gaulle in 1966, is a national monument to French engineering, technological innovation and “green” – in this case aquamarine – electricity.

It was the world’s first power plant to harness incoming and outgoing tides with bidirectional “bulb turbines” specially developed for the dam. The plant has a capacity of 240 Megawatts (MW), enough to cover the consumption of a city the size of Rennes with a population of 225,000.

EDF, which operates this national monument, awarded a contract to the Actemium Energie Hydraulique economic interest group to renovate and replace a range of equipment, a project that has become indispensable after 50 years of operation in a highly corrosive marine environment.

“VINCI Energies has the strength and agility to rapidly bring in workers from different region to provide the variety of skills required for this exceptional project as the need for them arises.”

Set up to address the full range of hydraulic engineering requirements on the Rance River and in the Alps, the EIG brings together the expertise and resources of Actemium Brest and Actemium Grenoble. Following completion of the studies phase conducted by the EIG and the renovation of the gates and direct current networks, Actemium Brest is now renovating the monitoring and control system of the first eight generators.

A state-of-the-art plant

“It is the strength of the VINCI Energies network that enables us to bring together employees from other regions who combine a range of expertise to work on the Rance dam,” says Loïc Gromellon, Regional Director within VINCI Energies.

At the tidal power plant, about 20 Actemium technicians are working to gradually replace the 24 generators or turbines in a project that involves the electrical cabinets, cables, instruments (sensors measuring temperature, frequency) and lastly the monitoring and control system. These PLCs ensure that electricity is generated at the right frequency and power.

“The renovation will also enable us to install state-of-the-art monitoring and control systems,” says Loïc Gromellon. These units, the “plant’s brain”, set the operating conditions for the generators and gates based on a programme set out by the operator, EDF. The turbines are replaced two by two and the operations are divided into three sets of eight generators, each with 10 MW capacity, so as to ensure uninterrupted production in line with the commitment made by EDF to the transmission system operator, RTE.

The three 18-month works stages will give the Rance plant a new lease of life and with it the Gaullist symbol of 100% renewable energy that is, in contrast to solar and wind energy, completely predictable.