What are the CO2 emissions of nuclear power?

In pro­por­tion to its pop­u­la­tion, France has the largest nuclear park in the world. Indeed, accord­ing to 2019 fig­ures, 72% of French elec­tric­i­ty comes from nuclear ener­gy, 20% from renew­able ener­gy and 8% from fos­sil fuels. Nuclear ener­gy enables France to be 50% ener­gy inde­pen­dent, while allow­ing it to export elec­tric­i­ty for profit.

Today, France’s objec­tive is to reduce its green­house gas (GHG) emis­sions by 40% by 2030, com­pared to 1990 lev­els. It may have to decrease these even more, how­ev­er, since Europe has decid­ed to accel­er­ate its decar­bon­i­sa­tion pro­gramme with its “Fit for 55” objec­tive (55% reduc­tion by 2030) that takes into account car­bon capture.

Accord­ing to opin­ion polls, many French peo­ple still think that nuclear pow­er emits CO₂, but the real­i­ty is quite dif­fer­ent. This mis­con­cep­tion is under­stand­able, how­ev­er, since the ener­gy tran­si­tion pro­gramme states that GHG emis­sions need to be reduced but our reliance on nuclear pow­er also.

We need to dif­fer­en­ti­ate between two concepts:

• CO₂ emis­sions of a tech­nol­o­gy dur­ing oper­a­tion: as for wind or solar ener­gy, nuclear ener­gy emits hard­ly any CO₂.
• The car­bon foot­print, which includes emis­sions dur­ing the entire life of the instal­la­tion, known as “from well-to-wheel”, that is, those result­ing from all phas­es of con­struc­tion, oper­a­tion and dismantling.

There are two units of impor­tance here: car­bon diox­ide emis­sions, expressed in grams of CO₂ per kWh, or gCO₂/kWh, and GHG emis­sions, which include all green­house gas­es in gCO₂eq./kWh. The impacts of oth­er GHGs are stan­dard­ised as “CO₂ equivalent”. 

For exam­ple, in the case of nuclear pow­er, in addi­tion to con­struc­tion, there is extrac­tion of ore, enrich­ment of ura­ni­um by ultra­cen­trifu­ga­tion, trans­port, pro­duc­tion and dis­tri­b­u­tion of elec­tric­i­ty and, of course, decom­mis­sion­ing and waste man­age­ment must be con­sid­ered, too.

Although such an analy­sis seems sim­ple, these para­me­ters are in real­i­ty extreme­ly com­plex to assess, since they must direct­ly take into account mea­sur­able activ­i­ties as well as indi­rect con­tri­bu­tions, pos­si­bly out­side our bor­ders. For exam­ple, for nuclear pow­er France imports its ura­ni­um from mines in Cana­da, Aus­tralia, Niger and Kaza­khstan, and must trans­port it after trans­for­ma­tion to our ports. On the oth­er hand, a sig­nif­i­cant part of the mate­ri­als and equip­ment is avail­able nationally.

If we look at oth­er means of elec­tric­i­ty gen­er­a­tion, there is a mas­sive amount of equip­ment that comes from abroad, such as wind tur­bines and solar pan­els, so we have to include their foot­print in our own.

The three tech­nolo­gies hydropow­er, wind and solar are very cli­mate effi­cient. Even an error in assess­ment of a fac­tor of two or three would not change this con­clu­sion. Solar pan­els, although a lit­tle less effi­cient, still rank well. But, each coun­try will ben­e­fit more or less from each of these technologies:

• Solar PV will be very effi­cient in a dry, low lat­i­tude cli­mate, and cer­tain­ly much less so near the Arc­tic Circle.
• Inter­mit­tent elec­tric­i­ty will have to rely on back­up capac­i­ty, which will very often be a nat­ur­al gas plant, thus reduc­ing its performance.
• Nuclear pow­er itself will not be able to meet peak demand and will be sup­ple­ment­ed by renew­able ener­gies, but also part­ly by fos­sil fuel pow­er plants.

This is why we use the emis­sion fac­tor of each coun­try’s elec­tric­i­ty mix. From this point of view, as long as its nuclear pow­er remains strong, France per­forms very well, if com­ple­ment­ed by hydro and oth­er renew­ables. By way of com­par­i­son, in 2020, the emis­sions of EU coun­tries were the fol­low­ing (in g/kWh): Swe­den (13), France (55), Aus­tria (83), Den­mark (102), Spain (190), Bel­gium (192), Italy (212), Ger­many (301), Hol­land (318) and Poland (724)¹.

We will lim­it our­selves to two ref­er­ence doc­u­ments, that of the ADEME (the agency of the Min­istry of the Envi­ron­ment), and that of the IPCC (the Inter­gov­ern­men­tal Pan­el on Cli­mate Change), the for­mer being rather hos­tile to nuclear ener­gy and the lat­ter neutral.

These fig­ures are very com­pa­ra­ble to those of the IPCC, with the notable excep­tion of nuclear pow­er, which has half the car­bon foot­print in France. This low fig­ure comes from the fact that the Georges Besse 2 plant (for iso­tope sep­a­ra­tion), which enrich­es ura­ni­um, is pow­ered by French elec­tric­i­ty, which is remark­ably car­bon-free (unlike oth­er coun­tries that have mas­tered this tech­nol­o­gy and which still rely heav­i­ly on fos­sil fuels to pro­duce their electricity).

Between oppo­nents and sup­port­ers of this or that ener­gy, the fig­ures may dif­fer, espe­cial­ly as the cal­cu­la­tions them­selves are tech­ni­cal­ly com­plex, and may even be the sub­ject of polit­i­cal choic­es: how can steel pro­duced in each coun­try be com­pared accord­ing to the lev­el of tech­nol­o­gy and the use of coal of more or less good quality?

It is in this sense that the two assess­ments by ADEME and the GHG are inter­est­ing because they are very sim­i­lar. The IPCC data have the advan­tage of being multi­na­tion­al, and the fig­ures obtained are eval­u­at­ed by experts from all over the world accord­ing to a high­ly struc­tured process, with peer reviews.

To meet the objec­tives of the 2015 COP21 – which led to the Paris Agree­ment, signed by 195 coun­tries com­mit­ting to act to con­tain the rise in tem­per­a­ture below 2°C by 2100 – France must, like oth­er nations, reduce its GHG emis­sions. This goal, which requires France to reduce its GHG emis­sions by 40% by 2030 (or even more with the new Euro­pean tar­gets, as men­tioned), can only be achieved if it makes a rad­i­cal shift towards a low-car­bon economy.

An analy­sis of our coun­try’s emis­sions clear­ly reveals the areas where action is urgent­ly need­ed: in 2019, trans­port and build­ings were respon­si­ble for 63% of emis­sions and it is repeat­ed­ly stat­ed that we will have to rein­dus­tri­alise our coun­try if we want to reduce our car­bon foot­print. The solu­tion can only come from an elec­tri­cal vec­tor which, accord­ing to the Inter­na­tion­al Ener­gy Agency (IEA), could car­ry 80% of the world’s ener­gy needs by the end of the cen­tu­ry (fos­sil fuels still pro­vide three quar­ters of glob­al con­sump­tion today).

Nuclear pow­er, with its low car­bon foot­print and pro­duc­tion flex­i­bil­i­ty, will nec­es­sar­i­ly play an impor­tant role, com­bined with hydropow­er and sol­id bio­mass (lim­it­ed) to pro­duce elec­tric­i­ty when it is need­ed. These con­trol­lable pro­duc­tions will be sup­ple­ment­ed by inter­mit­tent elec­tric­i­ty, pos­si­bly based on a mass stor­age of elec­tric­i­ty but they have yet to be demon­strat­ed. This switch from a “fos­sil » soci­ety to an “elec­tric” one is a real chal­lenge, how­ev­er, and will require huge invest­ments. Being long term and high­ly cap­i­tal inten­sive (this is true for both nuclear and renew­able ener­gies), our ener­gy future depends on clear, robust and long-term strategies.

Polit­i­cal whims and often unfruit­ful quar­rels have unfor­tu­nate­ly weak­ened France’s posi­tion, as clear­ly evi­denced by the surge in prices in the coun­try this autumn. With a view to shut­ting down all our coal-fired pow­er sta­tions by 2024, hav­ing refused to launch new nuclear pow­er sta­tions for 15 years and for­bid­ding the con­struc­tion of nat­ur­al gas-fired pow­er sta­tions, our con­trol­lable pro­duc­tion fleet no longer has the nec­es­sary pow­er. It is urgent to act, because even if nuclear pow­er is relaunched, this will take more than a decade and we will not be able to avoid the con­struc­tion of a few nat­ur­al gas pow­er plants as a tran­si­tion­al ener­gy source.

In France, EDF has embarked on a major refur­bish­ment of its reac­tors to extend their oper­a­tion under the safe­ty con­di­tions recog­nised by the Nuclear Safe­ty Author­i­ty. With the EPR2, it is also devel­op­ing a new mod­el that is more effi­cient in terms of both pro­duc­tion and cli­mate, with a gain of around 15 to 20%. We are still wait­ing on deci­sions, but the tide is turn­ing and we can hope for a real relaunch of nuclear pow­er in France and in Europe.

In par­al­lel, many oth­er efforts will have to be made to improve ener­gy effi­cien­cy and reduce our cli­mate foot­print by repa­tri­at­ing indus­tri­al activities.

Interview by Isabelle Dumé

For more:

• V. Nian, S. Chou, B. Su et J. Bauly, “Life cycle analy­sis on car­bon emis­sions from pow­er gen­er­a­tion – The nuclear ener­gy exam­ple”, Applied Ener­gy, n^o 1118, pp. 68–82, 2014
• https://www.ipcc.ch/languages‑2/francais/
• https://​www​.ademe​.fr : base car­bone ADEME
• https://www.edf.fr/groupe-edf/espaces-dedies/l‑energie-de-a-a‑z/tout-sur-l-energie/produire-de-l-electricite/l‑epr
• http://​www​.cap2030​.com