Post-doctorate in PEM Fuel cells development and characterizations
The objective of this post-doctoral position is to understand how a realistic manufacturing defect in the Membrane Electrode Assembly (MEA) can affect the performance loss and the degradation rate of PEMFC stacks. Among the most common defects, the lack/absence of active layer (particularly at the anode side where loadings are very low), the presence of agglomerates, cracks or excessive thickness in the active layers or in the microporous level of the GDL are often encountered locally (few cm²). Here, this work will rely on the expertise at CEA LITEN to produce MEA with a controlled structure (homogeneous deposits, good membrane|electrode interface, mapping of local catalyst loading). Both homogeneous and defective MEA with controlled properties, will be tested electrochemically.
The tests will notably include clever coupling between the different physical and electrochemical characterization methods possible ex-situ, operando or post-mortem. Among them, magneto-tomography, a technique based on measuring the magnetic field generated by the current passing through the stack, will continue to be developed. These measurements will make it possible to quantify the 3D effect of defects during operation. Finally, the post-doctoral fellow will use existing modeling tools to improve the prediction of the lifespan of PEMFCs related to the initial local properties of MEA.
All these experimental and simulation works will make it possible to correlate local operational heterogeneities and the degradation mechanisms associated with the defects depending on their nature or their positioning in the cell. Consequently, this study will provide some key-recommendations for the type and size of defects acceptable within MEA in relation with the operating and lifespan specifications of the PEMFC system.
Post doctoral position in solid state electrochemistry / ceramic materials / NH3 synthesis by electroreduction
Research into the electrochemical synthesis of NH3 focuses mainly on electrolysis cell configurations and materials, catalyst development, strategies for improving the selectivity of the N2 reduction reaction compared with that of water, and verification of the synthesis results. The post-doctorate proposed here will focus on high temperature (400-650°C) proton (H+) and anion (O2-) electrolysis processes offering the possibility of using H2O(g) and/or H2 to reduce N2.
The objectives of these studies will be as follows:
-identifying anionic O2- (SOEC for Solid Oxide Electrolysis Cell) and protonic H+ (PCEC for Proton Ceramic Electrolysis Cell) electrolysis cell materials suitable for NH3 synthesis,
-optimisation or development of these cells,
-quantification of the ammonia produced for each cell tested,
-identification of the first-order parameters needed to maximise NH3 production kinetics,
-drawing up a preliminary energy balance for comparison with the conventional Green Habor Bosch process.
Simulation of PEMFC flooding phenomena
The proton exchange membrane fuel cell (PEMFC) is now considered as a relevant solution for carbon-free electrical energy production, for both transport and stationary applications. The management of the fluids inside these cells has a significant impact on their performance and their durability. Flooding phenomena due to the accumulation of liquid water are known to impact the operation of the cells, causing performance drops and also damages that can be irreversible. With the use of thinner channels in ever more compact stacks, these phenomena are becoming more and more frequent. The objective of this post-doc is to progress in the understanding of flooding in PEMFCs. The work will consist in analyzing the link between the operating conditions, the design of the channels and the materials used in the cell. It will be based on a two-phase flow modeling approach at different scales, from the local scale at the channel-rib level, up to, via an upscaling approach, the level of the complete cell. The study will also be based on numerous experimental results obtained at the CEA or in the literature.
HPC simulations for PEM fuel cells
The goal is to improve TRUST-FC software -a joint development between LITEN and DES institutes at CEA- for detailed full 3D simulation of hydrogene PEM fuel cells and to run simulations on whole real bipolar plate geometries. Funded by AIDAS virtual lab (CEA/Forshungs Zentrum Juelich), a fully coupled electro-chemical, fluidic and thermal model has been built, based on CEA software TRUST. The model has been benchmarked against its FZJ counterpart (Open fuelcell, based on OpenFoam). The candidate will adapt the software and toolchain to larger and larger meshes up to billion cells meshes required to model a full bipolar plate. Besides, he will introduce two phase flow models in order to address the current technological challenges (local flooding or dryout). This ambitious project is actively supported by close collaboration with CEA/DES and FZJ.
Production of green hydrogen and ammonia from offshore energy
This subject is dedicated to the high potential of offshore wind power in the high seas, where it seems extremely complicated and expensive to install an electric transmission to a continental grid. In addition, the IMO, a United Nation agency that is responsible for environmental impacts of ships, adopted ambitious targets to reduce greenhouse gas (GHG) emissions from marine shipping. The IMO plan regulates carbon dioxide (CO2 ) emissions from ships and requires shipping companies to halve their GHG emissions by 2050 (compared to 2008 levels).
Different ways are being explored in order to identify the best low-carbon fuel that will be able to power new marine propulsion systems without GHC emissions (and others polluants like Sox, Nox…).
Hydrogen combined with a fuel cell is a good option for small application (fishing boat…). However, issues associated with hydrogen storage and distribution (low energy density) are currently a barrier for its implementation for large and massive marine application which drivess 80–90% global trade, moving over 10 billion tonnes of containers, solid and liquid bulk cargo across the world’s oceans annually.
Hence, other indirect storage media are currently being considered. Of these, ammonia is a carbon free carrier which offers high energy density. First studies and demonstration projects show that it could be used as a fuel coupled with a new generation of high-temperature fuel cells (SOFC) or internal combustion engines.
This project focuses on the green ammonia production on a high seas platform including an offshore wind farm that use renewable electricity to first generate hydrogen from water (via electrolysis) and nitrogen from air and then combine both in a Haber-Bosch process to synthesize ammonia. The objective is to develop modeling tools (Modelica / Dymola environment) in order to build, simulate and optimize "wind to ammonia" systems and energy management solutions to minimize the production cost of ammonia.