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