Climate change is affecting power grids, here’s what to expect

This sum­mer in France, many house­holds were left without elec­tri­city due to heat­waves, thun­der­storms or forest fires. These recent events high­light the strains on the country’s elec­tri­city grid, whilst rais­ing ques­tions about its abil­ity to adapt to glob­al warm­ing and the gradu­al elec­tri­fic­a­tion of human activities.

The effects of cli­mate change on the elec­tri­city sys­tem – and prob­ably the most obvi­ous ones – relate to trans­mis­sion and dis­tri­bu­tion infra­struc­ture. When sub­jec­ted to extreme tem­per­at­ures dur­ing heat­waves, cer­tain pieces of equip­ment such as trans­formers and sub­sta­tions age pre­ma­turely, oper­ate at reduced capa­city and may even suf­fer a short cir­cuit¹. In addi­tion, over­head power lines have a trans­mis­sion capa­city that depends dir­ectly on extern­al tem­per­at­ure. And the more they over­heat, the more they expand and come closer to the ground, pos­ing a risk to the pub­lic and the envir­on­ment². When out­side tem­per­at­ures exceed 35°C, cer­tain oper­a­tion­al meas­ures such as the redis­tri­bu­tion of power flows and a reduc­tion in elec­tri­city gen­er­a­tion, can be imple­men­ted to lim­it the risks³.

But “the resi­li­ence of the elec­tri­city sys­tem to cli­mate change is not solely a mat­ter of infra­struc­ture; it would be far too simplist­ic to stop at that obser­va­tion,” points out Phil­ippe Drob­in­ski, CNRS Research Dir­ect­or and Pro­fess­or at Ecole Poly­tech­nique (IP Par­is). Anoth­er con­sequence of cli­mate change is a reduc­tion in elec­tri­city gen­er­a­tion capa­city. “In sum­mer, our elec­tri­city sys­tem will become increas­ingly vul­ner­able,” explains Phil­ippe Drob­in­ski. “In fact, 80 % of it relies on water, a resource par­tic­u­larly affected by cli­mate change. This does not only con­cern France; this heavy depend­ence of the elec­tri­city sec­tor on water is a glob­al issue.”

In France, this depend­ence is due to the sig­ni­fic­ant share of hydro­elec­tri­city (11.4 % of total elec­tri­city gen­er­a­tion in 2025) and nuc­le­ar power (68.1 %) in the French elec­tri­city mix⁴. For a nuc­le­ar power sta­tion, water is essen­tial for the cool­ing sys­tem. Drawn from a river or the sea depend­ing on the loc­a­tion, the water is fed into the cool­ing cir­cuit, from which it emerges heated – the vast major­ity of which is dis­charged back into the nat­ur­al envir­on­ment. Water abstrac­tion and dis­charge are sub­ject to reg­u­lat­ory lim­its: if the river’s flow rate is too low or its tem­per­at­ure too high, the plant may be shut down to pro­tect the nat­ur­al envir­on­ment. How­ever, river flow rates and tem­per­at­ures are affected by heat­waves and droughts, which are them­selves altered by cli­mate change. The fre­quency and intens­ity of heat­waves and droughts have already increased in main­land France. And in a France that is 4°C warm­er, the num­ber of days with heat­waves between May and Septem­ber would increase ten­fold, accord­ing to the latest report from the Haut Con­seil pour le Cli­mat⁵.

The nuc­le­ar react­ors most sens­it­ive to cli­mate change could be out of ser­vice two to three times more often.

As a res­ult, the nuc­le­ar react­ors most sens­it­ive to cli­mate change could be out of ser­vice two to three times more often, caus­ing nation­al ther­mo­elec­tric power gen­er­a­tion to fall by 10 to 15 % by 2050 if green­house gas emis­sions con­tin­ue to rise⁶. A large part of Europe would see its power gen­er­a­tion affected to a sim­il­ar extent. As for hydro­elec­tric gen­er­a­tion, which is also depend­ent on water resources, it could fall by between 2.5 and 7 % in the Mediterranean. 

Finally, one last pil­lar of the elec­tri­city sys­tem is affected by the cli­mate: demand. With sum­mers increas­ingly char­ac­ter­ised by heat­waves, the grow­ing use of air con­di­tion­ing raises the ques­tion of rising elec­tri­city demand. “Added to this is the wide­spread elec­tri­fic­a­tion of vari­ous uses, par­tic­u­larly in trans­port,” explains Phil­ippe Drob­in­ski. “Bat­ter­ies do not cope well with high tem­per­at­ures, which increase their energy con­sump­tion.” RTE, the oper­at­or of France’s elec­tri­city trans­mis­sion net­work, fore­casts a rise in annu­al elec­tri­city con­sump­tion due to the shift from fossil fuels to elec­tri­city. But dur­ing heat­waves, con­sump­tion peaks are one of the major chal­lenges for the grid. These rel­at­ively brief peri­ods of very high elec­tri­city demand can put strain on the elec­tri­city grid. By 2050, RTE anti­cip­ates a rise in peak demand due to the use of air con­di­tion­ing, rising from 14 to 28 gigawatts.

And to make mat­ters worse, all these effects coin­cide in the sum­mer. Dur­ing a heat­wave, the elec­tri­city grid’s equip­ment over­heats, demand for elec­tri­city skyrock­ets due to air con­di­tion­ing… and some power sta­tions are shut down because of high tem­per­at­ures and low river flows. The weath­er events them­selves com­pound due to their inter­de­pend­ence, thereby increas­ing the pres­sure on the elec­tri­city sys­tem: repeated heat­waves lead to droughts, which in turn cre­ate ideal con­di­tions for the spread of wild­fires. A study⁷ pub­lished in 2023 iden­ti­fies the three factors most likely to cause a power sys­tem fail­ure in the west­ern United States: abnor­mally high tem­per­at­ures, abnor­mal sol­ar radi­ation and abnor­mally low wind speeds. These weath­er para­met­ers, which are dir­ectly influ­enced by cli­mate change, sim­ul­tan­eously cause an imbal­ance between sup­ply (which is fall­ing) and demand (which is rising).

Giv­en the impacts of cli­mate change that have already been observed and those yet to come, there is no doubt that the elec­tri­city grid needs to be adap­ted. RTE high­lights the need to replace net­work equip­ment – most of which was built dur­ing the second half of the 20^th Cen­tury, in a cli­mate very dif­fer­ent from today’s – and, in its 2025 Ten-Year Net­work Devel­op­ment Plan⁸, pro­poses a fully-fledged adapt­a­tion strategy to be imple­men­ted by 2060. Nev­er­the­less, the latest report from the Haut Con­seil pour le Cli­mat still high­lights sig­ni­fic­ant risks regard­ing the adapt­a­tion of the energy frame­work: in par­tic­u­lar, the body emphas­ises the weak­ness of strategies in the face of rare but extreme events, or in the face of epis­odes where nat­ur­al haz­ards occur in suc­ces­sion. For example: repeated heat­waves, pro­longed droughts, and major wildfires.

Anaïs Maréchal