Scientific direction Development of key enabling technologies
Transfer of knowledge to industry

PhD : selection by topics

Technological challenges >> Green and decarbonated energy incl. bioprocesses and waste valorization
5 proposition(s).

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Recycling of fluorinated polymers contained in new technologies for energy (NTE)

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire des technologies de valorisation des procédés et des matériaux pour les EnR

01-10-2021

SL-DRT-21-0502

emmanuel.billy@cea.fr

Green and decarbonated energy incl. bioprocesses and waste valorization (.pdf)

Fluoropolymers are today very widely used for their mechanical and chemical properties and their durability. Polymers are unavoidable in the field of NTEs such as proton exchange membrane fuel cells (Nafion membrane in PEMFCs), batteries (PVDF at electrodes), or photovoltaic panels (EVA at the glass cell interface). With the advent of carbon-free technologies, the issue of recycling has become central to bringing these technologies to market. Historically, recycling processes were designed for processing different technologies and large volumes. This has led to the establishment of pyrometallurgical processes (high temperature) that are robust, but destructive and non-selective. In a context constrained by strategic, legislative (recycling rate) and environmental issues, it is necessary to recycle "more" and "better". This thesis aims at finding new wet or dry ways for the treatment of fluorinated compounds. The use of ionic liquids for the solubilization of polymers will be a preferred route. Their intrinsic physicochemical properties (very low volatility and flammability) make them ideal candidates for overcoming safety and environmental issues. The thesis work will be divided into three parts. Firstly, a state of the art will be realized for the evaluation of conventional processes and media for the treatment of fluorinated compounds. The state of the art will be tightened on the fluorinated polymers used in the field of new technologies for energy (NTE). A second part will deal with the chemistry of polymers and solvents in which a polymer can be dissolved. A third part of a fundamental nature will aim at linking the macroscopic results to the structural evolutions of the polymers.

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New materials to decrease CO2 capture energetic cost

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire Micro-Sources d'Energie

01-10-2021

SL-DRT-21-0503

arthur.roussey@cea.fr

Green and decarbonated energy incl. bioprocesses and waste valorization (.pdf)

Reducing CO2 emission is the main challenge of our generation. The transition towards low carbon energy sources will take time and CO2 capture, either at emission sources or directly from the atmosphere, is a mitigation solution currently in fast development. CO2 capture is a cyclic process, with a first adsorption step who removes CO2 from a gas stream, followed by a thermal regeneration step, which yields highly concentrated CO2, which can be reused or stored. However, when directly captured from the atmosphere (~ 400 ppm), this process has a high cost ((100-400?/tCO2),[1],[2] due mainly to the energy needed during the regeneration step (~1500 kWh/tCO2). The PhD thesis candidate will synthesize new polyamines and study their interactions with CO2 and water with the objective of reducing the energetic cost of CO2 capture and to improe their thermal stability. [1] K. Z. House, A. C. Baclig, M. Ranjan, E. A. van Nierop, J. Wilcox, et H. J. Herzog, « Economic and energetic analysis of capturing CO2 from ambient air », Proc. Natl. Acad. Sci., vol. 108, no 51, p. 20428, déc. 2011. [2] M. Fasihi, O. Efimova, et C. Breyer, « Techno-economic assessment of CO2 direct air capture plants », J. Clean. Prod., vol. 224, p. 957-980, juill. 2019.

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Ammonia synthesis from N2 and H2O using an electrochemical-chemical lithium cycling

Département des Technologies des NanoMatériaux (LITEN)

Laboratoire des technologies de valorisation des procédés et des matériaux pour les EnR

01-10-2021

SL-DRT-21-0522

Parviz.HAJIYEV@cea.fr

Green and decarbonated energy incl. bioprocesses and waste valorization (.pdf)

Hydrogen is a promising energy carrier if it is produced from renewable energy and stored / transported safely and at low cost. Ammonia has undeniable advantages for the storage of H2 with high energy densities (17.8% wt H2) and existing infrastructure for its distribution. Ammonia is produced on a large scale using the Haber-Bosch process under severe operating conditions (?450 ° C, ?200 atm). The hydrogen required for this process is produced from natural gas, emitting 3% of anthropogenic CO2. An alternative is to synthesize ammonia directly from renewable electricity using a lithium-based electrochemical-chemical cycle. This cycle involves different stages including the nitridation of Li (formation of Li3N), the hydrolysis of Li3N to generate ammonia, and finally the electrolysis of LiOH to regenerate Li and thus close the cycle. Setting up this cycle under moderate temperature / pressure conditions involves optimizing each steps in terms of kinetics and efficiency. Generating ammonia under these moderate conditions would greatly limit the ecological impact linked to this molecule.

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Multi-criteria thermo-economic analysis and optimisation of complementarities between CO2 (CCU), biomass (BE-CCS) and the electrical vector (H2 production, battery storage), within the framework of the French and European energy mixes.

Département Thermique Conversion et Hydrogène (LITEN)

Laboratoire des systèmes énergétiques pour les territoires

01-10-2021

SL-DRT-21-0778

guillaume.boissonnet@cea.fr

Green and decarbonated energy incl. bioprocesses and waste valorization (.pdf)

Within the framework of studies on the closing of the carbon cycle, it is essential to look at the complementarity between several sources of carbon (CO2 and biomass) and sources and vectors of decarbonated energy (electricity, H2). This constitutes a complex system including many variables and constraints, which it is necessary to study with means of optimization and multi-criteria analysis, in order to make the most of it. The thesis will be articulated around 3 axes - Elaboration, consolidation of a methodology for optimization and multi-criteria analysis of energy systems including non-fossil carbon as a material resource and decarbonated energies. - Development and consolidation of a database of technological solutions including non-fossil carbon as a material resource and decarbonated energies. - Study of several systems according to the philosophy of the scheme: coupling carbon and electricity, in particular through hydrogen.

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A study of diffusion welding of alloy 800 and its application to compact heat exchangers

Département Thermique Conversion et Hydrogène (LITEN)

Laboratoire Conception et Assemblages

01-10-2021

SL-DRT-21-0950

emmanuel.rigal@cea.fr

Green and decarbonated energy incl. bioprocesses and waste valorization (.pdf)

Alloy 800 is a highly corrosion resistant steel suitable to manufacture steam generators (SG). Diffusion welding is a solid state joining process carried out through the application of high pressure and temperature to materials. When applied to grooved plates, it allows to obtain highly compact heat exchangers and this technological solution is envisaged for the fabrication of the SG of Small Modular nuclear Reactors. However, diffusion welding of alloy 800 is difficult because a profuse precipitation of carbides and oxides at interfaces during welding. First, the PhD subject consists in studying this phenomenon for different initial condition of the material and, more generally, in studying how the material evolves during a high temperature exposure. Conditions favourable to diffusion welding will be defined. Then, the diffusion welding process will be simulated using models previously developped at the laboratory and/or within partner academic labs. The models will need to be completed. Those two first items will allow to define suitable diffusion welding conditions that will be used for the fabrication of joints. The latter will be characterised, both from the microstructure and the mechanical properties point of view. The link between the initial microstructure, the process parameters, the final microstructure and the porperties will be studied.

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