In France, where energy depends largely on nuclear power, and to a lesser extent on hydropower, the prospect of repeated droughts raises the question of the resilience of the electricity network.
After closely monitoring their electricity consumption in winter, the French are invited, as the fine weather approaches, to save water. Among the sectors that depend on this precious resource, agriculture first comes to mind. But in France, water is also energy. Nuclear and hydraulics, which respectively represent 63% and 11% of French electricity production, according to theagence OREare exposed to the effects of global warming. At a time of debate on the delicate sharing of blue gold, the question arises: could drought and heat waves one day turn off both the tap and the electricity?
In more ways than one, the year 2022 was exceptional in terms of energy: the geopolitical hazards linked to the war in Ukraine, the climate crisis and technical problems (which led to the shutdown of several nuclear reactors for operations maintenance) have highlighted the need to reduce our energy consumption, particularly electricity.
The energy transition will cause demand to explode
If, in the fall, it was necessary to consider wearing a turtleneck at home, “the summer period remains a low period in terms of electricity consumption”, recalls Nicolas Goldberg, energy market expert for the consulting firm Colombus Consulting. Admittedly, air conditioning is developing, but it remains far from exerting on the electrical network a pressure comparable to that of heating in winter, he explains. The risk of seeing episodes of heat and drought harm it in the short or medium term remains unlikely, assures this specialist. “Not for this decade, anyway.”
Because things will change. THE Global warming will generate more frequent, longer and more intense extreme phenomena and, consequently, increase the risk of drought and heat waves that can affect the flow and temperature of waterways during the summer. This, while the demand for electricity will continue to increase. “Assuming that we succeed in the energy transition, the French economy will be, tomorrow, much more electrified than it is today. Electricity consumption will be smoother, less seasonal and above all, much higher”, justifies the expert.
According to the scenarios imagined by the RTE network manager, electricity consumption will drop from 459.3 TWh in 2022 to a range of 555 to 745 TWh by 2050 (PDF). To take the all-electric turn, the President of the Republic announced in February 2022 in Belfort his desire to develop “massively” renewable energies and nuclear. But these carbon-free energies are already seeing their functioning hampered by global warming.
A very greedy nuclear fleet
The French nuclear fleet consumes between 400 and 500 million cubic meters of water each year (out of the 4.1 billion m3 consumed in the country, all uses combined). But to function, the three-color power plants take a lot more. For Nicolas Garnier, general delegate of the Amorce association, which supports local authorities, this distinction between withdrawal and consumption of the latter nevertheless maintains the illusion of a “magic water”. “Even if a large part of the water withdrawn is returned, the French nuclear fleet needs 13 billion m3 to operate”he insists.
He takes the example of the Rhône and the economic, industrial and agricultural activities that share the water upstream of the Bugey (Ain) or Tricastin (Drôme) power stations. In summer, when the river flow is at its lowest and water needs are highest, what will happen?
“Should we ask ourselves the question of prioritizing uses and depriving certain activities of water upstream, to allow power plants to take the water they need?”
Nicolas Garnier, general delegate of the Amorce associationat franceinfo
In early 2022, in Belfort, Emmanuel Macron announced the construction of at least six reactors, the first of which should come on stream by 2035-2037, in order to “to restart” the sector. But Dn a note dated April 17 and unveiled by AFP, the Nuclear Safety Authority (ASN) highlights guard against “the potential cumulative effects linked to the presence of several sites” along the same river. In a report published on March 21, the Court of Auditors also calls on EDF to “reinforce your research” so that its cooling systems are more “sober in water”, lamenting that“no innovation” does not currently allow us to meet the challenge, for the current fleet as well as for future EPRs.
“For sites on the banks of the river, with unchanged regulations and without adaptation of existing installations, the risks of unavailability of units should increase”, for its part, warns RTE, which recommends installing the new power stations by the sea, where they will not be exposed to the problems of drought and the drying up of waterways.
The risks of too hot water
Without significantly penalizing production (reactors closed for several months are affected by corrosion unrelated to global warming), the scorching weather has already given a glimpse of its harmful power. Last year, ofn the beginning of May, in the midst of an early heat wave, EDF slowed down for a few hours one of the reactors of the Blayais power station (Gironde), on the banks of the Garonne, in order to discharge less hot water into a river with reduced flow. In June, this was the case for Saint-Alban power station (Isère), on the Rhône. These operations are not uncommon, but they usually occur later in the summer. According tohe prospective studies cited by the Court of Auditors, the “unavailability” linked to global warming could be multiplied by three to four by 2050.
In July and August, the Bugey, Blayais, Golfech (Tarn-et-Garonne), Saint-Alban and Tricastin power plants obtained waivers from ASN to exceed the regulatory temperature limits for the water discharged , fixed for each installation. “If such derogations are taken, it is because there is a danger to the capacity to produce”, deciphers Nicolas Garnier. Interviewed in July 2022 by the Tribunethe president of the ASN, Christophe Quintin, declared moreover: “CThis heat wave should push us to rethink the temperature thresholds of the rivers in force.” Yet, recalls Nicolas Garnier, “These temperature rules are not arbitrary: eThey were established to protect the fauna and flora and the functioning of the ecosystem of the waterways”.
Hydropower, a driving force for renewables
The main source of renewable energy in France, hydropower, is itself particularly exposed to drought. Conditions in the summer of 2022 caused annual hydropower production to plunge to its lowest level since 1976, at 49.6 TWh (always according to RTE). That is a decrease of 20% compared to the 2014-2019 average.
In the case of hydraulic production, “water is fuel” summarizes Nicolas Goldberg. “In the event of severe drought, run-of-river installations produce less, because the flow rate is lower. Those that store water are also affected, because the stock is less full.” And as if the prospect of repeated droughts and heat waves were not enough, “if there is no snow in the winter in the mountains, it becomes difficult to fill the dams in the spring”, he continues.
In its 2022 report, RTE noted that “inventories reached historic lows in mid-July”before returning in the fall to “medium levels”. Despite this poor performance, the sector can boast of having saved the winter, according to EDF boss Luc Rémont. Questioned on February 28 before a commission of the National Assembly, he considered hydraulics as “one of the elements that allowed us to get through the winter” without cut. For Nicolas Garnier, the sector plays the role “of an assurance, which can be used to avoid tensions”. But no one imagines betting more on this source of renewable energy, for lack of being able to model, and therefore anticipate, the impact of climatic hazards on its operation.
Sobriety rather than “the electricity fairy”
RTE’s scenarios for 2050 all imagine a stable share of hydroelectricity in the energy mix, between 9 and 10%, close to what it represents today (11%). Since “lamost all suitable sites are already equipped”the network manager estimated in a report in 2020 that in the long term, the French hydropower fleet could only “to increase again slightly with some new small installations, over-equipment on existing sites and possibly some new pumped storage stations”without “represent a first-rate stake” compared to the evolutions expected for wind or solar power.
For Nicolas Goldberg, the proper functioning of hydraulics will partly depend on the rapid development of other renewable energies. “Because she is modular and storable, hydroelectricity will make it possible to integrate renewable energies into the network, by managing intermittences”, he explains, pointing to the under-investment from which this historic sector suffers. And according to the expert, all renewable energies will have to accommodate climatic constraints.
“In summer, the biggest problem will be the lack of wind. Heat waves also affect the efficiency of solar panels. This is why if we want to succeed in the energy transition, we will need sobriety, not just at home, but on a structural level.”
Nicolas Goldberg, energy market expert for Columbus Consultingat franceinfo
Example in transport, where “we must develop public transport rather than wanting to switch everyone to electric”.
In light of the climatic constraints to come, “we cannot consider that the electricity fairy will solve all the problems”continues Nicolas Garnier, who invites “don’t put all our eggs in one basket”. “With local authorities, we are seeing an explosion of heating network projects, solutions based on local and renewable energies”, he raises. A multitude of small solutions adapted to the territories. Don’t they say that small streams make big rivers?
