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.
Intégration CMOS à canal dual en technologie FDSOI : comparaison "enrichissement en Ge" vs. "Epitaxie localisée"
LETI is a major laboratory in the european microelectronics research, especially in the thin film FDSOI research (Fully Depleted). We propose innovative solutions for the next ITRS roadmap generations (sub 22nm), such as the integration of ultrathin Silicon-Germanium (SiGe) layers in the channel of p type transistors (in order to increase the hole mobility, and to adjust the threshold voltage of pMOSFETs).
The first results show significative gains for hole mobilityy and Vth,p tunning (C. Le Royer et al. ESSDERC 2010, IEDM 2011) but also for basic circuits (L. Hutin et al. IEDM 2010).
In order to further improve the Fully Depleted CMOS DualChannel integration, it is necessary to quantify in details the advantages and the possible drawbacks (form the process and from the electrical performance point of view). LETI wants to compare the two following approaches for SiGe based pMOSFETs (cointegrated with SOI nMOSFETs featuring 6nm body thickness):
.SiGe/SOI hetrostructures ("Localized SiGe epi" on SOI)
.SiGe-On-Insulator ("localized Ge enrichment" on SOI)
Other issues have also to be considered such as the initial substrate (SOI, sSOI) or the Ge content in the SiGe layer…
Kinetic study of biocide effect in nanocellulose_based food film
This project will study the kinetic of biocide effect of a nanocellulose-based film food. The main aim is to graft Ag and/or ZnO NPs on and inside halloysite particles that have a characteristic shape of twisted sheets and therefore could acting as NPs tanks. The localization of NPs outside halloysite could induce a fast biocide effect with limited duration whereas the internal grafting could produce longer biocide effect. This project gathers all steps from the film food synthesis, its nanocharacterization to the evaluation of its toxicological effect on bacteria. The final goal is to find one or many halloysite functionalizations allowing to extend the biocide effect in film food and to transpose it to other types of materials.
Neutronic thermal-hydraulic coupling in heterogeneous Sodium Cooled Fast Reactor (SCFR)
Within the frame of ASTRID (Sodium cooled Fast Reactor) prototype development, update of calculation methodologies using new generation of codes benefiting from High Performance Computing (HPC) and advanced coupling capabilities is underway. These methods are expected to be integrated in ASTRID safety demonstration. In particular, development of coupled neutronics/thermal-hydraulics/fuel mechanics methodologies during accidental transients is underway.
Coupling Neutronics and thermal-hydraulics in double phase flow conditions (either sodium + vapor sodium or sodium + other gaz) can be used for:
• Loss of Flow transients (LOF, sodium + vapor sodium)
• Gas insertion transients.
This coupling is of special interest with cores strongly relying on axial leakage for safety consideration (like CFV cores [ICAPP11]).
The work proposed is to further develop the implementation of 3D coupling with state of the art CEA codes (APOLLO3, FLICA, CATHARE, TRIO etc.) to analyze the two type of transients stated above.
Silicon nanowire elaboration for microelectronic applications
In order to realize high capacity integrated capacitor, one approach consists in developing electrode with high specific surface. In this work, we propose to perform capacitor integrating silicon nanowires. The first part of this study will be devoted to the understanding and to the optimization of Si nanowires CVD growth process. In parallel, properties of nanowires obtained by electrochemical silicon etching will be assessed and will be compared to CVD nanowires characteristics. According to the electrical performances, different strategies (metallization Silicuration…) will be envisaged in order to enhance their electrical conductivity.
Development of Monte-Carlo methods for the simulation of radiative transfer: application to severe accidents
This post-doctoral subject concerns the development of Monte-Carlo ray-tracing methods for modeling radiation heat transfer in the context of severe accidents. Starting from a well-developed software framework for Monte Carlo simulation of particle transport in the context of reactor physics and radiation protection, we will seek to adapt existing methods to the problem of radiative heat transfer, in a high-performance computing framework. To do this, we will develop a hierarchy of approximations associated with radiative heat transfer that are intended to allow the validation of simplified models implemented in the context of the numerical simulation of severe accidents in nuclear reactors. Focusing on algorithm and simulation performance, this work is intended to be a "proof of principle" of the possible software mutualization around the Monte-Carlo method for particle transport on the one hand and radiative heat transfer on the other hand.
Low temperature process modules for 3d coolcube integration : through the end of roadmap
3D sequential integration is envisaged as a possible solution until the end of CMOS roadmap. Different process modules have been developped @ 500°C for planar FDSOI technology in a gate first process. However, regarding bottom transistor level stability in CoolcubeTM integration, and yield consideration, the need to reduce further the top transistor temperature down to 450°C should be explored.
The post-doc will have in charge the development of specific technological modules at low temperature both 500°C and 450°C for FDSOI planar devices to acquire a solid knowledge in low temperature CMOS process integration. The specific low temperature gate module will be addressed on planar devices. The threshold voltage modulation will also be studied.
The work will be performed in collaboration with the technological platform process of LETI for the low temperature modules development. The electrical characterization in collaboration with the characterization laboratory and the TCAD simulations team of LETI.
Characterisation of vanadium alloys
Vanadium alloys, investigated in the scope of application in fusion reactors, are potential candidates for fuel cladding of future sodium cooled or gas cooled fasts reactors. Then, in 2009, CEA launched a program aiming to assess this solution according to future reactor requirements.
Preliminary investigation of V-4Cr-4Ti plates was done at DMN/SRMA/LA2M (i) on a reference Japanese grade and (ii) on a specific grade fabricated for CEA study. Works haw focuses on recrystallisation structure after cold working (grain size and morphology, effect of annealing temperature), and on fine microstructure (occurrence of Ti(O,C,N) precipitation). In 2011, fabrication of vanadium tube by hot extrusion is planned to be relevant of the final cladding geometry. The proposed post-doc investigation aims to monitor the fabrication and to specify the impact of fabrication process on microstructure, recrystallisation dynamic and mechanical properties.