The CEA provides the French public authorities and industry with the technical expertise and innovation needed to develop low-carbon energy systems. This mission is performed by all the CEA’s operational divisions, and in particular the Energy Division (DES).

More information on the DES

Research carried out at the CEA on low-carbon energy is supported by strong upstream research, the development of predictive simulation tools and a broad range of test reactors, some of which are unique in the world.»



The number of major programmes which shape the CEA’s research on low-carbon energy

To address the current and future challenges of the energy transition, which is necessary to combat climate change and ensure the sustainability of the way we live, the CEA has opted for an approach that incorporates not just the scientific aspects but also the technical, economic, societal and political aspects when structuring its research.

Target: to become carbon neutral by 2050. For this major transition to be successful, an energy system must be built today which is not only as energy-efficient as possible but also provides everyone with all the benefits they need day-to-day - in terms of lighting, heating, transport, etc. - under the best possible conditions. This means taking all the system’s component parts into account: production of low-carbon energy in order to move away from fossil fuels (oil and coal), operation and optimisation of energy networks (storage, control and conversion), distribution on various scales (from national to local), limiting energy losses (energy efficiency and management of energy consumption) and recycling of materials.

The CEA is one of the only French research organisations that is working simultaneously on both types of low-carbon energy that are currently available - nuclear and renewable - as well as on cross-cutting topics such as network management, energy storage, simulation and even controlling sources and consumption. It is therefore ideally positioned to develop the essential integrated approach to energy issues. In 2020, at the request of the French public authorities, and based on an internal discussion process carried out to address the major challenges involved in the energy transition as effectively as possible, the CEA reorganised its research and created the Energy Division (DES) to cover the whole field.

This initiative addresses two major aims. The first is to help the public authorities and industry (both SMEs/SMIs and large groups) to produce roadmaps for the various technologies which will contribute to becoming carbon neutral by 2050 and, more generally, to assess the relevance of the various energy scenarios. The second is to prioritise, from the point of view of science and scientists, a shared, cross-cutting approach.

Research on low-carbon energy at the CEA is organised into thirteen main programmes. It is supported by strong upstream research, the development of validated predictive simulation tools and a broad range of test reactors, some of which are unique in the world. This research focuses on four key areas.


Production of decarbonised energy

with support for current and future nuclear energy (2nd and 3rd generation reactors, fuel cycle, 4th generation reactors, SMRs and defence), the development of coupled systems (using SMRs other than for power generation, combining nuclear with hydrogen or with heat production applications) and photovoltaic solar. The CEA is also working on hydrogen production by high temperature electrolysis and thus actively contributing to the development of a French hydrogen sector.


Technical operation of the energy system

to increase its effectiveness and efficiency (grid flexibility solutions and energy storage methods, smart load management on networks and power conversion possibilities).


Management of available resources

(materials and equipment) considering their entire life cycle (from the processes used to manufacture them through to their recycling), and studying methods for converting CO2 into useful energy (circular carbon economy).


Performance of the overall system

the progress of which is studied by assessing various energy scenarios using a combined technical and economic approach.

The results obtained in 2020 and early 2021 and those expected in the coming months will consolidate this global research strategy.


Key events 2020

Heterojunction photovoltaic cells: a successful transfer!
Decarbonised energy

Heterojunction photovoltaic cells: a successful transfer!

— Following the finalisation of the transfer of the HET technology developed at CEA-Liten to ENEL Green Power at the end of 2019, its teams carried out several optimisation campaigns in 2020 with the company, passing the 25% efficiency mark and achieving annual productivity of 200 MW at its Catania factory in Sicily (Italy). This is a major achievement, as it places the CEA technology on the global premium photovoltaic technologies roadmap and heralds Europe’s return to the small group of photovoltaic cell producers. These technologies will be essential for the success of the energy transition in countries faced with significant restrictions on land.

HET: Heterojunction technology (HJT) is one of the most efficient technologies for photovoltaics. This solution combines two different semi-conductor materials, for example one layer of crystalline silicon and one of amorphous silicon (whereas homojunction technology combines two areas of the same material).
CEA-Liten: One of the institutes in the CEA's Technological Research Division. Its role is the creation of solutions to address climate, energy and environmental issues.

Hydrogen production is ramping up
Decarbonised energy

Hydrogen production is ramping up

— High-temperature electrolysis (HTE) technology, developed by the CEA, made significant progress in 2020. The work focused on two main areas: improving the durability of the ceramic cell through a better understanding of the degradation mechanisms associated with its microstructure, and the production of the first new format stack. The new architecture for future power stacks (6 times larger than those made until now at the CEA) has been validated on intermediate stacks, which were made and tested on equipment in CEA-Liten's pilot unit in Grenoble. These developments will be transferred to Genvia (established jointly with Schlumberger in March 2021) which will be responsible for the industrialisation of the technology.

CEA-Liten: One of the institutes in the CEA's Technological Research Division. Its role is the creation of solutions to address climate, energy and environmental issues.

Fonctionnement du système énergétique
Operation of the energy system

Focus on the batteries of the future!

Three questions for Séverine Jouanneau, Head of the Department of Electricity and Hydrogen for Transport (DEHT) at CEA-Liten.

What part does CEA-Liten play in supporting the battery sector?

S. J.: Le CEA-Liten is part of a European initiative to support the battery sector, with an R&D support role for industry across the entire value chain. We are working in particular on improving materials for electrodes, manufacturing processes, electrolytes and chemistries, right through to the implementation of the technologies developed and their assessment on prototype cells. On the materials side, we are seeking, for example, to improve the lamellar components of positive electrodes in order to reduce the amount of cobalt used, and thus reduce their environmental impact. In all cases, it is a matter of detailed characterisation of the phenomena occurring at the interfaces in order to optimise them, which is crucial for improving performance.

What significant results were achieved in 2020?

S. J.: In 2020, we successfully produced and implemented the first electrodes by extrusion rather than by coating! This process does away with the use of solvents that are toxic and difficult to reprocess. We have succeeded in getting as far as making the first cells, and the performance tests suggest results that match our expectations. On the materials side, we have identified several potential areas of work for developing hybrid or even solid electrolytes. These will enable us to design much safer and much more compact cells than is currently possible with current liquid electrolytes. Finally, in the field of electrodes, we have improved the performance of the existing materials and selected those which will be used in the first 3rd generation lithium-ion batteries which will be produced in French factories in 2023-2024.

What are the challenges ahead?

S. J.: Since the 3rd generation is just about ready, we are going to focus our efforts on the next generations. We have already identified potential electrolytes for the 4th generation, : we now have to select and implement that or those which will enable us to reach the industrial performance levels we are looking to achieve. There are still a few obstacles to overcome, such as managing the interfaces in a “totally solid” battery, to maintain good ion and electron conduction. One of the things we are working on for future generations is innovative technologies such as lithium-sulphur chemistry, which will enable us to reach a new level in terms of performance. This research, and future developments, will be guided by the environmental impacts of the life cycle and the recycling of these products. This will apply when the components and processes are chosen, or even at the design stage.

CEA-Liten: One of the institutes in the CEA's Technological Research Division. Its role is the creation of solutions to address climate, energy and environmental issues.
Coating: Surface treatment consisting of applying a coating, which is generally liquid, to a substrate (paper, textile, plastic film, metal, etc., followed by drying and, if required, cross-linking (chemical or physical formation of one or more three-dimensional matrices).
3rd generation: 3rd generation lithium-ion batteries (and the next generations) have better performance levels than the first and second generations which are currently on the market, particularly in terms of energy storage.

Fuel cells are counting on TRUST

Fuel cells are counting on TRUST

— The numerical modelling and simulation of PEMFCs was developed over 15 years ago at CEA-Liten, on microscopic scales (electrode, porous media theory) and on a cellular scale. Objective: to obtain reference simulation results without compromising on the complex geometry of this technology or on the physical accuracy of the phenomena that are present. PEMFCs are highly multi-physics and multi-scale and a reference simulation for this technology requires the power of high performance computing (HPC). Hence the use of the Energy Division’s CFD TRUST platform, which was initially developed for nuclear applications, in order to make use of both its HPC capacity and its open-source aspect.

A crucial step was taken at the end of 2020, with the first coupled, parallel thermal simulation to reproduce, on a small-scale model, the release of heat caused by the cell during its operation.

This result provides the essential building blocks for more complex modelling, due in 2021, which will incorporate all the physics of the cell’s core and the gas and thermal mechanisms, which are at work in its structural support (bipolar plate).

PEMFC: Acronym for Proton Exchange Membrane Fuel Cell
CEA-Liten: One of the institutes in the CEA's Technological Research Division. Its role is the creation of solutions to address climate, energy and environmental issues.

First view of the core of an SMR using APOLLO3®

First view of the core of an SMR using APOLLO3®

In 2020, the CEA carried out the first neutron characterisation for the core of NUWARD, the French SMR project, using the APOLLO3® code. APOLLO3® is a new generation computer code and a major update of APOLLO2 and CRONOS2 that were developed by the CEA over 40 years ago for modelling the physical phenomena which occur between the fuel and the neutron flux. APOLLO3® is a multi-scale and “multi-technology” code as it is suitable for various types of reactor (pressurised water reactors, research reactors and fast reactors). It is used to simulate, even more accurately than its predecessors, the self-sustained fission reaction: birth of the neutrons (fission), movements of the neutrons and interactions with all the materials in the reactor, and disappearance of the neutrons (absorption). Its use in the context of the NUWARD project will enable innovative, complex modelling to be carried out which is particularly well-suited to new reactor concepts like SMRs.

SMR: Acronym for Small Modular Reactor

The NUWARD project

The aim of the NUWARD project, which is led by EDF in partnership with the CEA and supported by Naval Group and TechnicAtome, is to develop a PWR-based small modular reactor by 2030. This will enable the French nuclear industry to offer power plants in the 300 to 400 MWe range on the export market, to replace fossil fuel thermal power plants. In this project, the CEA is responsible for the reactor core neutronic design studies and validation of the neutron and thermal-hydraulic computing tools. It is also involved in thermal-hydraulic studies and testing.

VINON-LOCA teste ses premiers crayons

VINON-LOCA is testing its first fuel rods

An initial test on an irradiated fuel rod has been carried out in the new VINON-LOCA device at the CEA’s STAR facility at its Cadarache site. This test marks an important step forward, as it confirms the continuation of a research programme to study fuel behaviour in LOCA accident conditions, in particular fuel fragmentation or relocation mechanisms.
It consisted of subjecting a segment of irradiated UO2 fuel rod to a thermal transient representing the first phase of a LOCA (transient of 5 °C/s up to 1 000 °C). After thermal qualification on a dummy rod in early 2019, this first test on a refabricated mini-rod was used to check that the pressurisation system, the heating system and the associated instrumentation (online monitoring of the pressure and composition of the fission gases, metrology and gamma spectrometry bench) were operating correctly. This decisive step qualifies the VINON-LOCA facility, the design of which was started in early 2016 with the aim of carrying out highly instrumented LOCA tests for online observation of the fuel fragmentation or relocation phenomena, which have a major influence on meeting the safety criteria concerning the cladding temperature. The result obtained is in line with the predictions of the Alcyone rod thermomechanical code used for numerical simulation of the experiment. The next step is the commissioning of improved instrumentation incorporating a gamma camera for online monitoring of fuel relocation.

LOCA: Acronym for Loss-Of-Coolant Accident

Accident resistant mini-rods ready for irradiation

Accident resistant mini-rods ready for irradiation

— To give fuel cladding better resistance to accident scenarios, it can be made of ceramic materials rather metal, in particular silicon carbide based composites (SiCF/SiC). The target in 2020 was to make mini ATF rods, the strength of which could be tested experimentally. This target was met with success!
Although the Energy Division’s (DES) teams are experienced in the fabrication of nuclear quality SiCf/SiC composite tubes, introducing the concept of a rod that is viable in PWR operating conditions would involve overcoming several obstacles, the most difficult of which include the leaktight closure of the tube and protection against the hydrothermal recession of the SiC. This technical challenge has involved highly cross-disciplinary work, making use of the expertise of the DES and the Technological Research Division (DRT) to create composite objects (tubes and plugs), provide design support, carry out surface treatment and provide the brazing technology for leaktight closure.

ATF: Acronym for Accident-tolerant Fuel
PWR: Acronym for Pressurised Water Reactor. PWRs are the most commonly used type of nuclear reactor in the world.

Research reactors
Research reactors

The JHR project passes a major new milestone

— Following the implementation of the measures for more stringent project control required by the French government in mid-2019, the organisation of the RJH project was restructured in 2020 and integrated in the technical platform at the CEA’s Cadarache worksite. The construction and installation of the JHR’s mechanical components continued successfully during the year, in full compliance with the safety rules and those imposed by the pandemic.
In November, one of the project’s major milestones was passed with the delivery of the reactor core vessel and its installation in the reactor cavity. This operation involved twenty people and took ten days. This mechanical part is one of the main components of the JHR’s primary system as it will eventually contain its core with 37 fuel assemblies for which it will provide constant cooling. This mechanical component meets stringent safety requirements as it is classified as nuclear pressure equipment. Its detailed design required six years of engineering, led by TechnicAtome, and factory fabrication and tests.
The successful installation of this equipment means that the JHR project can continue its progress with the mechanical integration of other components of the primary system, in line with the project’s new 2021-2023 roadmap.

JHR: Acronym for the Jules Horowitz reactor. The successor of the Osiris research reactor, which is now shut down at the CEA’s Saclay site, the JHR is designed to be an experimental tool capable of observing and helping to understand the behaviour of materials in extreme nuclear environments. It will also be used to supply nuclear medicine with the short-lived radioelements used by medical imaging services for diagnostic purposes.