Near Orléans, in the ultra-secure enclosure of an anonymous building like everywhere in France every year, Enedis technicians practice managing the risk of load shedding, these rotating blackouts throughout the territory. Since the start of the school year, in view of a difficult winter, the exercises have “intensified”.

“We are ready”, reassures Olivier Loriot, regional director of Enedis in Center-Val de Loire in the middle of the control screen walls of the regional driving agency (ACR), which monitors the electricity distribution network for this area, 24 hours a day, 7 days a week.

Fear of cuts was reignited after the latest forecast from RTE, the high-voltage network operator, which warned on Friday of a “high” risk of tensions on the electricity system in January, due to the slower restart than expected. of EDF nuclear reactors – nearly half are still shut down. Clearly, the electricity production could prove to be insufficient to meet the needs.

Still unthinkable a few months ago, such a scenario unrelated to climatic hazards would be “totally unprecedented”, underlines RTE, which manages the distribution of electricity to households, businesses (excluding large industrialists) and communities, i.e. 1.4 million kilometers of low and medium voltage lines.

In these circumstances, RTE does not rule out using the EcoWatt device, a sort of “electricity weather forecast” and in particular the activation of its red alert signal, which warns the population of a risk of three days before.

Load shedding is THE ultimate measure to avoid the “black-out”, the generalized and uncontrollable breakdown, we insist at Enedis.

But it is not “inevitable”, underlined Mr. Loriot, recalling the levers to avoid it such as “the sobriety efforts” promoted by the government and the “erasure” of the consumption of large industrialists, against remuneration.

The challenge is to crush the peaks of consumption, which extend from 8 a.m. to 1 p.m. and from 6 p.m. to 8 p.m., these times when France lights up, heats up, cooks, works, produces at the same time.

And if that’s not enough? Managers can lower the voltage by 5%, a measure that saves 4% of consumption but “imperceptible” for the user except for a slightly less bright bulb. And it is only as a “very last resort” that “power cuts” could be operated by Enedis at the request of RTE.

– Algorithm-

“Control towers” for the security of the distribution network, the 28 regional control agencies would then be responsible for remotely activating these two-hour rotating blackouts, in neighborhoods in turn, on the whole territory. Excluding some 1,400 priority sites: defense, electricity production but also hospitals, prisons, according to a list drawn up by the prefectures.

Three days in advance, “we receive a first message from RTE” announcing “a risky situation”, on D-2 the estimates on the number of 100 MW blocks to be weaned (one block is equivalent to 100,000 customers), and on D-1 “we have a targeted load shedding plan that we will be ready to activate the next day, according to the choices of an algorithm”, schematizes Sébastien Sarrazin, head of the ACR Centre-Val de Loire.

After confirmation from RTE, the evening before D-Day, the EcoWatt site and application will publish the map of the departments potentially concerned and from 9:30 p.m., users will be able to check whether their address is located in the load shedding plan.

Voltage dips and load shedding are carried out at the level of “source stations” (2,300 in France): visible in the countryside or sometimes hidden in buildings, these kinds of small buildings contain several “departures”, kinds of circuit breakers allowing supply neighborhoods or villages.

“In the event of load shedding, one or more departures may be cut off in order to maintain a production/consumption balance”, summarizes Sandrine Hartmann, head of the “source-post” department.

At the heart of a winter marathon, Enedis agents already have a new national training scheduled in a few weeks.