Carbon emissions from French nuclear power: 4g of CO2 per kWh

On 16 June 2022, EDF published its life cycle analysis of the French nuclear fleet. This detailed analysis will make it possible to identify the stages and flows that contribute most to the balance sheet with a view to improvement, EDF emphasizes. It is also an opportunity to clarify the various figures sometimes cited in the democratic life of France. The conclusion is that the French nuclear kWh emits less than 4g CO2 equivalent.

In the scientific literature, the emissions of the various energies can vary according to the methodology used or the country studied. The reference figure for nuclear power at the international level is that of the Intergovernmental Panel on Climate Change (IPCC): 12 g CO2 eq/kWh. As a reminder, the median is the figure that separates a data set into two equal parts. However, the methods of uranium extraction and enrichment, the carbon footprint of construction materials, and the strategy for managing radioactive materials are all factors that can vary – slightly – the carbon emissions per kWh. In France, the Agency for the Environment and Energy Management (Ademe), in its database, estimates the emissions of a nuclear kWh at 6 g of CO2. By comparison, the emissions from gas-fired power stations are estimated again by Ademe at 418 g CO2 per kWh and those from coal-fired power stations at 1058 g CO2 per kWh. As for renewable energies, the kWh in France is around 10 g for wind energy and 30 g for photovoltaic solar energy. Based on data from the fleet in 2019, EDF updates clarify and confirm the low-carbon character of nuclear power with a kWh of less than 4 g of CO2. This exercise is all the more critical given that in France, only 30% of people under 25 years old approve of the idea that “nuclear energy is an asset in the fight against climate change,” compared with 50% of people over 50 years old (source: EDF Barometer).

The methodology meets a set of specifications: ISO standards

The life cycle assessment (LCA) is a standardized method that must meet the requirements of ISO 14040-44. It is based on the inventory of material and energy flows for the different phases of the product’s life cycle, from the extraction of raw materials to waste management. The credibility of the LCA is enhanced by the critical review of an expert committee following ISO/TS 14071.

The scope of the study includes data from the fleet in 2019, i.e., 34 900 MW reactors, of which 22 are “moxed,” 20 1300 MW reactors, and 4 1450 MW reactors. The study does not take into account the transport of electricity.

In addition to CO2, the results of the analysis include various emissions such as methane (CH4), nitrous oxide (N2O), sulfur hexafluoride (SF6), etc. This is expressed as “grams of CO2 equivalent per kWh”.

Life Cycle Assessment (LCA) perimeter, ©EDF

The results of the study

Details of CO2 emissions from French nuclear power plants, ©EDF

The breakdown of nuclear emissions, which total 3.7 g CO2 eq. per kWh shows the particular importance of the upstream part of the cycle while decommissioning, maintenance and waste storage have negligible weight.

Sensitivity studies show that a 60-year operation reduces the carbon footprint by 8% (3.4 g CO2/kWh) compared to a 40-year operation. The impact of a 10% change in annual electricity production compared to 2019 is 0.1 g CO2/kWh. EDF concludes that the overall sensitivity offers a range of 2.9 to 4.6 g CO2 eq/kWh.

Beyond greenhouse gas emissions

The analysis looked at different environmental impacts, radioactivity, impact on human health and marine and terrestrial ecosystems, land footprint, resource depletion, etc. For more information, find the study on the EDF website. ■