Cables stretching over hundreds of meters, a handful of 250-tonne transformer stations, a few empty reels that once held kilos of coiled copper and aluminum, all with a superb panorama of the Chartreuse mountains, Bauges and Belledonne flooded with sunshine… At the end of February, the Savoie-Piémont interconnection site looks like an electrician’s paradise.
On this 5-hectare plot, nestled at the bottom of the valley, about twenty kilometers from Chambéry, it has been almost seven years since the manager of the Electricity Transmission Network (RTE), its Italian equivalent Terna and their service providers have been on foot of work. Their mission: to lay a 190 kilometer link across the Alps to connect the networks of France and Italy.
Or, more precisely, to increase by 60% the import-export capacities of electrons between the two countries compared to 2009. The work, started in 2015, is nearing completion. “We carried out empty tests, commissioning is scheduled for the second quarter of 2022”, confides Xavier Bourgeat, project manager at RTE, a hint of relief and pride in his voice.
A technological feat
Not that the project suffered from industrial hazards. But running a 130mm-diameter DC power line across mountains through highways, tunnels and overpasses takes a lot more than sweat and a few shovels. “These are high precision tasks, which do not suffer from any error”, insists Xavier Bourgeat. In France, it is also the first line to follow underground, the route of a highway. A major challenge for the workers, who had to provide meticulous work to connect the different sections of cable, while keeping traffic open.
This passage under the Fréjus tunnel has, however, made it possible to avoid the difficulty of a passage over the mountains. Beyond this particular logistics, the RTE project manager also took care to limit the environmental impact. Passing through axes already created, on the one hand, but also with the implementation of measures to limit the use of products dangerous for nature during the creation of the converter station.
RTE’s Savoie-Piedmont interconnection project, which began in 2015, is about to be completed.
Alban PERNET
So many feats which moreover well deserve a record, that of the longest direct current underground connection in the world. In terms of power, this Franco-Italian cable represents an import and export capacity of 1200 MW, the equivalent of a nuclear reactor or the consumption of an agglomeration like that of Lyon. A necessary operation while the existing lines between the two nations were regularly saturated, Italy requiring a lot of electricity from France.
Once connected and commissioned, the station will then be completely emptied of its occupants: everything will be controlled remotely, from the center of Saint-Denis or those in Europe or the region. It is only during annual maintenance that the site will again welcome workers, with the arrival of 120 to 130 people. In this logic of self-management and independence, many systems for detecting leaks and preventing the spread of faults have been installed, in order to limit human arrivals as much as possible.
A European craze
More generally, this project is in no way a trial run for RTE. For several years, the manager has multiplied programs on all sides of France, with the ambition of doubling exchange capacities by 2035. The investments are heavy. The Savoy-Piedmont project alone exceeds one billion euros. But for Thomas Pertuiset, director of interconnections at RTE, the game is well worth the effort.
First at the economic level, because “the connection with adjacent countries allows prices to converge downwards”. For a market player, it can indeed sometimes be more advantageous to buy surplus production from one of its neighbors, the cost of which is lower than the same electricity produced more expensively on its own territory. The European Commission also considers that the interconnections are of great benefit to the whole of Europe. It aims for import-export volumes equivalent to 15% of the electricity capacity of the Member States by 2030. In its mix scenarios for 2050, RTE envisages up to 37 GW of export capacity, against 17 GW today. today. Enough to multiply the sites, to develop or modernize the links.
At the level of security of supply, then. “These cables allow solidarity between countries and, therefore, to ensure at all times the balance between supply and demand”. Although this winter there was little support for the European electricity market with the surge in prices, we sometimes forget to emphasize the beneficial role of the latter in the balance of the network. “The interconnections made it possible to meet peak demand due to the shutdown of nuclear power plants. Without them, we would certainly have had to do some load shedding or lower the network voltage”, underlines Jacques Percebois, Director of the Center for Research in Economics and Energy Law (Creden) and specialist in electricity markets.
Indispensable asset for the transition
This dimension will be increased tenfold in the years to come. With the massive integration of renewable energies, interconnections provide additional flexibility for integrating non-controllable wind or solar production into the network. In this regard, the European Union relies on the phenomenon of expansion, in other words the capacity of a region to compensate for an excess or a deficit of electricity production thanks to the needs or contributions of another region.
“For example, when there is a lot of wind coming from the Baltic Sea, wind power generation is very important in Germany. Thanks to the interconnections, it can export this non-storable electricity to France, which needs it at peak times” , explains Jacques Percebois. Thomas Pertuiset also recalls that these exchanges make it possible to avoid oversizing the electricity network and therefore overinvestment.
That being said, even if the consumption peaks are different according to the lifestyles of the different countries, which seems to allow complementarity, it remains unrealistic to hope for electricity production that responds perfectly to the scale of Europe. “We saw it with the Azores anticyclone in December, when the wind ran out over the whole continent”, sums up Jacques Percebois. An episode that generated a halt in wind production across the continent. An observation which obviously calls for the installation of new electrical capacities in France, so as not to rely solely on those of our neighbours.