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