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Renewables: yields vary according to climate

sylvain Cros
Sylvain Cros
Research Engineer at the Dynamic Meteorology Laboratory of École polytechnique (IP Paris)
Riwal Plougonven
Professor at École polytechnique (IP Paris) and Senior Lecturer at the Dynamic Meteorology Laboratory (LMD)
Key takeaways
  • According to the WMO and IRENA, global warming is having an impact on the production of renewable energies, particularly wind, solar and hydroelectric power.
  • Some regions, such as southern Africa and South-East Asia, could experience seasonal difficulties in supplying their electricity grids.
  • Hydroelectric production is directly linked to rainfall patterns and could decrease in regions subject to drought, while increasing at high latitudes.
  • Fluctuations in wind generation could particularly affect densely populated regions, with declines of up to 10 or 30%.
  • The key: using a mix of renewable energies to compensate for variations and continue to decarbonise our production.

At the end of 2023, the World Mete­o­ro­log­i­cal Organ­i­sa­tion (WMO) and the Inter­na­tion­al Renew­able Ener­gy Agency (IRENA) warned1: “A bet­ter under­stand­ing of cli­mate fac­tors and their inter­ac­tions with renew­able resources is vital to ensure the resilience and effi­cien­cy of ener­gy sys­tems and asso­ci­at­ed tran­si­tions.” The mas­sive tran­si­tion to renew­able ener­gies is essen­tial to con­tain man-made glob­al warm­ing: their total installed capac­i­ty must rise from 3,870 GW in 2023 to 11,000 GW in 2030 to lim­it warm­ing to 1.5°C2.

But the two agen­cies empha­sise the impact of glob­al warm­ing itself on ener­gy pro­duc­tion. Of the four indi­ca­tors con­sid­ered, all are impact­ed. This applies to wind pow­er, solar pow­er, hydro­elec­tric­i­ty and ener­gy demand. “It is essen­tial that polit­i­cal deci­sion-mak­ers antic­i­pate the future of ener­gy infra­struc­tures and assets, tak­ing into account the effects of cli­mate change and the result­ing increase in demand,” explained Francesco La Cam­era, Direc­tor Gen­er­al of IRENA, in a press release. In its lat­est syn­the­sis report3, the Inter­gov­ern­men­tal Pan­el on Cli­mate Change (IPCC) states that the impact of cli­mate change on elec­tric­i­ty pro­duc­tion should not com­pro­mise mit­i­ga­tion strate­gies on a glob­al scale. On the oth­er hand, it points out that the region­al impact can be sig­nif­i­cant, par­tic­u­lar­ly for wind and hydro­elec­tric pow­er. Regions such as south­ern Africa and South-East Asia could find it dif­fi­cult to pow­er their grids in cer­tain sea­sons. Con­verse­ly, South Amer­i­ca could con­sid­er reselling sur­plus energy.

The global impact of cloud cover

Let’s start with solar ener­gy, which has the great­est pro­duc­tion and expan­sion poten­tial. Elec­tric­i­ty pro­duc­tion is direct­ly linked to the amount of sun­shine – which varies accord­ing to lat­i­tude – and the pres­ence of clouds. “Cloud cov­er depends on tem­per­a­ture, humid­i­ty and pres­sure fields in the atmos­phere, which are them­selves influ­enced by cli­mate change,” explains Syl­vain Cros. In 2022, the load fac­tor4 – i.e. the yield – has changed very lit­tle com­pared with the peri­od 1991–2020. IRENA has observed the biggest changes (+3 to +6%) in Bolivia, Paraguay and Argenti­na, coun­tries already ranked among those receiv­ing the most solar irra­di­a­tion. By 2050, a study pub­lished in Nature Sus­tain­abil­i­ty5 iden­ti­fies a dou­bling in the num­ber of low-effi­cien­cy days in sum­mer in the Ara­bi­an Penin­su­la, and con­verse­ly a halv­ing of these days in south­ern Europe. For an inter­me­di­ate sce­nario of green­house gas emis­sions (RCP4.5, for which warm­ing reach­es 2.7°C by the end of the cen­tu­ry), the changes in solar pro­duc­tion in sum­mer in 2050 are mod­er­ate: ‑4% for the Ara­bi­an Penin­su­la, +5% for Cen­tral Europe, +3% for the Ata­ca­ma Desert, ‑2% in south-east Aus­tralia and north-west Africa and +2% in Chi­na and south-east Asia.

On a glob­al scale, the vari­a­tions in pro­duc­tion linked to cli­mate change are there­fore very small. Accord­ing to the IPCC, these vari­a­tions are unlike­ly to com­pro­mise solar energy’s abil­i­ty to sup­port the ener­gy tran­si­tion. “Pro­jec­tions show that the rise in tem­per­a­ture increas­es cloud cov­er, main­ly in arid regions,” explains Syl­vain Cros. This is due to an increased evap­o­ra­tion of water from soils and oceans, com­bined with an increase in con­vec­tion, which favours a rise in alti­tude and con­den­sa­tion into clouds. “But there are oth­er fac­tors that con­tribute to cloud cov­er, and these mod­els are far more uncer­tain,” adds the sci­en­tist. As for socio-eco­nom­ic fac­tors, these are dif­fi­cult to pre­dict. Tech­no­log­i­cal advances are increas­ing the yield of pho­to­volta­ic pan­els. Syl­vain Cros adds: “The rate of deploy­ment is anoth­er impor­tant fac­tor: solar pan­els have become so cheap that the speed of their deploy­ment could off­set the effects of the drop in irradiation.”

Regional variations and wind generation

Anoth­er impor­tant mode of renew­able ener­gy pro­duc­tion is wind pow­er. By com­par­ing the load fac­tor for the year 2022 with the peri­od 1991–2020, the WMO-IRENA note sig­nif­i­cant changes. Many Euro­pean coun­tries are record­ing a decrease of 10% or more, and the drop exceeds 16% in Cen­tral Amer­i­ca and Papua New Guinea. Con­verse­ly, increas­es of 8% are seen in sub-Saha­ran Africa, Mada­gas­car, Bolivia, Paraguay, Korea, and the Unit­ed States. But stud­ies seem to show that nat­ur­al cli­mate vari­abil­i­ty (the alter­nat­ing El Niño-La Niña phe­nom­e­na, for exam­ple) large­ly explains these vari­a­tions, rather than warm­ing linked to human activities.

“Changes in sur­face tem­per­a­ture are well under­stood in cli­mate pro­jec­tions. On the oth­er hand, changes in atmos­pher­ic cir­cu­la­tion are much more dif­fi­cult to mod­el, as there are many mech­a­nisms that can influ­ence wind pro­duc­tion6,” says Riw­al Plougonven. As a result, it is dif­fi­cult to iden­ti­fy a clear large-scale sig­nal for the future. The IPCC esti­mates that long-term wind ener­gy resources will not change sig­nif­i­cant­ly in future cli­mate sce­nar­ios. How­ev­er, cer­tain regions could be affect­ed by sig­nif­i­cant vari­a­tions, either from one year to the next, or from month to month. In a sum­ma­ry of 75 stud­ies7, the authors note a reduc­tion in pro­duc­tion poten­tial in the west­ern Unit­ed States for the sec­ond half of the 21st cen­tu­ry, and a down­ward trend for most of the north­ern hemi­sphere (Europe, Rus­sia, China).

Con­verse­ly, wind pow­er pro­duc­tion in Cen­tral and South Amer­i­ca, south­ern Africa and South-East Asia is show­ing an upward trend. In a study pub­lished in Feb­ru­ary 20248, oth­er authors note sig­nif­i­cant decreas­es between now and 2100 for the worst-case sce­nario of GHG emis­sions – around ‑10%, for exam­ple, for most of the Euro­pean Union and the Unit­ed States. They point out that this decline par­tic­u­lar­ly affects dense­ly pop­u­lat­ed regions, increas­ing the impact. “The mag­ni­tude of these changes can be sig­nif­i­cant, in the region of 10–30% depend­ing on the region,” notes Riw­al Plougonven. But he qual­i­fies that: “Most stud­ies focus on the worst-case sce­nario for GHG emis­sions (SSP5‑8.5) and pro­jec­tions for the end of the cen­tu­ry. How­ev­er, this sce­nario is unlike­ly, and the hori­zon – even if it is inter­est­ing – is too far away com­pared with the time scales of the wind ener­gy sector.”

With regard to hydropow­er, the indi­ca­tor eval­u­at­ed in the WMO-IRENA report shows a reduc­tion in 2022 in South Amer­i­ca, East Asia, Cen­tral and East Africa and West­ern Europe. On the oth­er hand, there will be an increase in Cana­da, Mex­i­co, Rus­sia, India, Nepal, South Africa, Aus­tralia and the Scan­di­na­vian coun­tries. As with solar ener­gy, these obser­va­tions are main­ly linked to the La Niña cli­mate regime in place in 2022. Hydro­elec­tric­i­ty pro­duc­tion is direct­ly linked to water avail­abil­i­ty and is mod­u­lat­ed by tem­per­a­ture and rain­fall inten­si­ty. As for the future, a large pro­por­tion of hydro­elec­tric pow­er sta­tions (61% to 74%) are locat­ed in regions where sig­nif­i­cant declines in riv­er flow are pro­ject­ed as ear­ly as 2050. Over­all, it is esti­mat­ed that high lat­i­tudes will see an increase of 5–20%, while regions sub­ject to drought will see a decrease of 5–20% (this con­cerns North and Cen­tral Amer­i­ca, south­ern Europe, the Mid­dle East, Cen­tral Asia, and south­ern South America).

Important projections for finding solutions

It is impor­tant to con­sid­er these pro­jec­tions when plan­ning the deploy­ment of renew­able ener­gies. Some regions of the world could find them­selves in a win-win sit­u­a­tion, “ben­e­fit­ing” from the increased pro­duc­tion of sev­er­al ener­gy sources. Con­verse­ly, oth­er regions could be dou­bly or triply affect­ed. The WMO-IRENA report takes the case of the region com­pris­ing Botswana, Mozam­bique, Namib­ia, South Africa, and Zim­bab­we: in June 2022, solar pro­duc­tion was reduced, but the region record­ed sig­nif­i­cant increas­es in hydro­elec­tric­i­ty and wind pow­er pro­duc­tion. By con­trast, by Octo­ber 2022, most indi­ca­tors were falling, putting elec­tric­i­ty sup­plies at risk. “The use of a mix of renew­able ener­gies is key to ensur­ing that vari­a­tions can off­set each oth­er,” points out Riw­al Plougonven. Final­ly, elec­tric­i­ty exchanges between regions could mit­i­gate these effects: for exam­ple, the greater poten­tial for wind pow­er in North Amer­i­ca could off­set the reduc­tion in Mex­i­co. The WMO-IRENA empha­sise the role of ear­ly warn­ing sys­tems in secur­ing ener­gy through­out the world.

Riw­al Plougonven con­cludes: “It is clear that these vari­a­tions linked to cli­mate change must be tak­en into account to opti­mise our pro­duc­tion of renew­able ener­gies, but this does not call into ques­tion the mas­sive and nec­es­sary deploy­ment of these ener­gies to decar­bonise our ener­gy.” The last major effect of cli­mate change on the ener­gy tran­si­tion? Ener­gy demand.

Anaïs Marechal
1WMO, IRENA (2023), 2022 Year in Review: Cli­mate-dri­ven glob­al renew­able ener­gy poten­tial resources and ener­gy demand.
2Web­site con­sult­ed on 26 April 2024: https://​www​.ire​na​.org/​D​i​g​i​t​a​l​-​c​o​n​t​e​n​t​/​D​i​g​i​t​a​l​-​S​t​o​r​y​/​2​0​2​4​/​M​a​r​/​S​y​s​t​e​m​i​c​-​C​h​a​n​g​e​s​-​N​e​e​d​e​d​-​t​o​-​T​r​i​p​l​e​-​R​e​n​e​w​a​b​l​e​s​-​b​y​-​2​0​3​0​/​d​etail
3Clarke, L., et al. 2022: Ener­gy Sys­tems. In IPCC, 2022: Cli­mate Change 2022: Mit­i­ga­tion of Cli­mate Change. Con­tri­bu­tion of Work­ing Group III to the Sixth Assess­ment Report of the Inter­gov­ern­men­tal Pan­el on Cli­mate Change, Cam­bridge Uni­ver­si­ty Press, Cam­bridge, UK and New York, NY, USA. doi: 10.1017/9781009157926.008.
4The load fac­tor is the ratio between the ener­gy pro­duced over a giv­en peri­od and the ener­gy that could have been pro­duced dur­ing that same peri­od if the ener­gy pro­duc­tion equip­ment had been oper­at­ing con­stant­ly at its rat­ed pow­er, i.e. under opti­mum con­di­tions of use.

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