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

PhD : selection by topics

Technological challenges >> Advanced hydrogen and fuel-cells solutions for energy transition
4 proposition(s).

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Robustness and performances of improved electrodes for solid oxide cells application

Département Thermique Conversion et Hydrogène (LITEN)

Laboratoire essais et systèmes

01-10-2021

SL-DRT-21-0289

maxime.hubert@cea.fr

Advanced hydrogen and fuel-cells solutions for energy transition (.pdf)

Solid oxide cells (SOCs) are electrochemical devices operating at high temperature that can directly convert fuel into electricity (fuel cell mode ? SOFC) or electricity into fuel (electrolysis mode ? SOEC). In recent years, the interest on SOCs has grown significantly thanks to their wide range of technological applications that could offer innovative solutions for the transition toward a renewable energy market. However, despite of all their advantages, the SOCs lifetime is still insufficient to envisage the industrial deployment of this technology. Indeed, the SOCs durability remains limited by various degradation phenomena including a mechanical damage in the electrodes. For instance, the formation of micro-cracks in the so-called ?hydrogen' electrode is a major source of degradation. However, the precise mechanism and the full impact of the micro-cracks on the electrode performances are still unknown. By a multi-physic modelling approach, it is proposed in this thesis to establish the link between the loss of performances and the mechanical damage in the hydrogen electrode. Once the model validated on dedicated experiments, a sensitivity analysis will be conducted to provide relevant guidelines for the manufacturing of improved robust and performant electrodes. One or two solutions will be selected and evaluated after manufacturing for final validation.

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Hydrogenation of Liquid Organic Hydrogen Carrier by electrochemical reduction

Département des Technologies des NanoMatériaux (LITEN)

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

01-10-2021

SL-DRT-21-0471

vincent.faucheux@cea.fr

Advanced hydrogen and fuel-cells solutions for energy transition (.pdf)

Hydrogen is expected to be the energy carrier of tomorrow due to the versatility of its ways of production and use. Nevertheless, its storage remains a major technological and scientific challenge. An alternative to the compression or liquefaction of H2 - energy-intensive and expensive processes - consists in storing and transporting hydrogen at atmospheric pressure and at ambient temperature (via existing infrastructures) using Liquid Organic Hydrogen Carrier (LOHC). These molecules can undergo reversible hydrogenation / dehydrogenation cycles in the presence of a catalyst. This technology therefore makes it possible to transport hydrogen from its production site (via electrolysis) to its site of use thanks to the these liquid molecules. A hindrance to the commercial deployment of this technology is in the energy efficiency of the whole process and the cost of the hydrogenation / dehydrogenation reactors. Indeed, hydrogenation / dehydrogenation reactions are highly exothermic / endothermic and require relatively high temperatures and efficient catalysts, often based on platinum group metal (PGM). In addition, the hydrogenation step requires the prior generation of H2 by electrolysis. The implementation of a direct hydrogenation of LOHC molecules at room temperature and pressure by electroreduction, would minimize the energy needs associated with this hydrogenation step, and would open the field of application of this LOHC technology.

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Predictive analysis, synthesis and validation of PGM free catalysts for a relevant decomposition of NH3 at lower temperature

Département des Technologies des NanoMatériaux (LITEN)

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

01-10-2021

SL-DRT-21-0523

jerome.delmas@cea.fr

Advanced hydrogen and fuel-cells solutions for energy transition (.pdf)

Hydrogen is expected to be the energy carrier of tomorrow due to the versatility of its ways of production and use. However, conventional storage solutions (under pressure, liquid H2,...) have some drawbacks (cost, energy requirement, losses by diffusion or boiling). In this context, different alternatives exist like ammonia. Ammonia has undeniable advantages for the storage of H2 with high energy densities (108 kg H2/m3 NH3 at 20°C-8.6bar; 17.8% wt H2) and existing infrastructure for its distribution. Furthermore, its use either as NH3 or as H2 after decomposition makes it possible to consider ammonia for multiple applications. Its decomposition is endothermal and a high temperature (> 700 ° C) is mandatory to ensure its decomposition with high kinetics. This temperature implies the aging of the catalysts and has a strong impact on the mechanical strength of the reactors with time. Developing catalysts allowing the efficient decomposition (kinetics, cost) of NH3 at lower temperature, based on theoretical and experimental approach, would open the field of application of NH3 technologies.

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Prediction of PEM water electrolyzer lifetime by multi-physics modeling

Département de l'Electricité et de l'Hydrogène pour les Transports (LITEN)

Laboratoire Modélisation multi-échelle et suivi Performance

01-10-2021

SL-DRT-21-0838

pascal.schott@cea.fr

Advanced hydrogen and fuel-cells solutions for energy transition (.pdf)

The cost of proton exchange membrane water electrolyzer (PEMWE) remains the bottleneck for moving the technology to the market place. A tradeoff between the loading of the catalyst and the objective to reach 80 000 hours of lifetime with high efficiency is necessary. The future generation of MEA (Membrane electrode assembly) have a low loading of catalyst (0.4mg.cm² at the anode side) with a thin membrane. The effects of ageing phenomena become visible during the first thousand hours. Different strategies to improve the lifetime exist, from material improvement (catalyst loading, coating) to optimal operating strategies of the electrolyzer. The challenge is to estimate the gain of lifetime without running a full test (80000 hours). Some AST (Accelerating Stress Tests) are developed to evaluate the new developments on lifetime. The objectives of this PhD thesis is to improve the understanding of degradation mechanisms and predict the lifetime of PEMWE and in particular the catalyst and membrane degradations inside the MEA (Membrane Electrode Assembly). CEA's multi-physics and multi-scale modeling approach will be used, coupled with in-situ experimental data provided by or collected at NREL. In particular, the modeling of degradation mechanisms in MEA operation will be developed using CEA's strong background on fuel cell modeling, including degradation mechanisms that lead to catalyst and membrane degradation. The following focus areas will be addressed: ? Statistical analysis of experimental data to correlate the main degradation mechanism to the operating conditions ? Development of the catalyst and membrane degradation models, based on existing CEA model ? Validation of the degradation model based on existing experimental data. New tests will be defined and realized to better identified the model parameters The final objective is to propose new AST for PEMWE. The validation of the new AST on experimental data will be performed. The thesis will be located at CEA Grenoble France, with several missions to NREL, Colorado, USA

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