For a long time, the grid was expanded to keep pace with consumption. This is no longer the case: today, changes in the electricity mix are the main driver of network growth. In its current state, the network has sufficient capacity to manage foreseeable trends in power demand the next 10-15 years, but considerable changes will be needed to adapt it to the mix the Multiannual Energy Programme calls for in 2035 (especially the fivefold increase in wind and solar capacity over 15 years, the decommissioning of 12 nuclear reactors in addition to the two at Fessenheim, and the closure of coal-fired plants).

In the near term, adaptations at the margins will suffice to accommodate new renewable energy capacity. Solutions based on the use of smart grids and optimal dimensioning of the network will make it possible to use existing infrastructure in an optimal way.
Over the longer term, structural modifications of the grid will be necessary. The technical solutions required are being carefully analysed and will depend on a variety of factors, including the nature of the new generation capacity to be connected and its geographic location.

The energy transition will require adapting the network, taking into account new challenges: the intermittency of renewable generation, its uneven geographic distribution, and new electricity uses. RTE must come up with flexible solutions to balance these new kinds of electricity generation and consumption.
RTE anticipates that the electricity grid’s flexibility requirements will increase substantially starting in 2030.

Against this backdrop, RTE has launched the “RINGO” experiment for storing electricity on its grid.
RTE initiated the experiment at three sites in France and with three different consortia: Vingeanne (Côte d’Or) will use equipment from Nidec Asi, while Bellac (Haute-Vienne) will rely on Saft/Schneider and Ventavon (Hautes-Alpes) on Blue Solutions/Engie Solutions/SCLE INEO.
Work began in 2020 at all sites.

The goal of the experiment is to simultaneously test the storage of occasional and local surplus renewable electricity (wind and solar) that cannot be carried over the network and its release elsewhere. This will ensure that the system operates in a neutral way vis-à-vis the market.
With its 10 MW of storage capacity, equivalent to output from five wind turbines, RINGO will help prevent renewable electricity losses and limit the construction of power lines.

The new 225 kV Cusset – Saint-Amour underground line, linking the third arrondissement of Lyons to Vaulx-en-Velin through Villeurbanne, was brought into service. It was the last phase of work on the “Lyon Câblenergie” project, launched in 2010, to upgrade the high-voltage network in Greater Lyons.

This modernisation project also involved extensive restructuring of the grid to accommodate the development of new neighbourhoods and the region’s economic expansion. Seven underground power lines (68 km) were renewed, and three substations were extended and modernised. In all, RTE has since 2011 upgraded more than 50% of the electricity network in the Greater Lyons area.

A key step in the renovation of the network in Haute-Durance, a new 225 kV overhead line spanning nearly 58 km between Serre-Ponçon and l’Argentière was brought into service in September 2020.

RTE introduced a major programme several years ago to upgrade the power system in Haute-Durance. The first steps were to bring three lines into service:

• 2016: 63 kV line between Briançon and Le Monêtier-les-Bains;
• 2018: 63 kV line between l’Argentière-la-Bessée and Briançon;
• 2019: 63 kV line between l’Argentière and Monêtier-les-Bains.

This new line provides an entirely upgraded path for electricity to travel between the lake in Serre-Ponçon and Serre-Chevalier, further improving security of supply to the Hautes-Alpes. Yet supply will not be entirely secure until the last phase is completed and the new Pralong substation in Embrun is brought into service in 2021. Power will be fed to it from a second 225 kV line starting in Gap, work on which is nearly complete.
By the time the project is finished, RTE will have taken down some 200 km of overhead lines located near close to 600 homes or remarkable sites (Serre Ponçon lake, fort in Mont-Dauphin, Col du Lautaret and Col du Galibier mountain passes).