Économie hydrogène

Résumé

Léconomie hydrogène ou économie de l'hydrogène est le modèle économique dans lequel le dihydrogène (de formule chimique ) servirait de vecteur d'énergie commun pour mutualiser les différents types de production d’énergie et pallier le problème de l’intermittence des énergies renouvelables. Ce principe est envisagé pour la première fois par Jules Verne en 1874, puis de façon plus détaillée par John Burdon Sanderson Haldane en 1923, et l'Allemagne nazie l'utilise pour produire des combustibles synthétiques à partir du charbon. La production d'hydrogène est évaluée en 2021 à (millions de tonnes), dont l'essentiel pour le raffinage (élimination du soufre) et la production d'ammoniac ; cette production provient pour 62 % du gaz naturel, 18 % du pétrole, 19 % du charbon, 0,7 % d'une énergie fossile avec captage et valorisation du et 0,04 % de l'électrolyse de l'eau. L'économie de l'hydrogène est de plus en plus invoquée pour ses potentielles perspectives d'avenir, en particulier :

Source officielle

https://fr.wikipedia.org/wiki/%C3%89conomie_hydrog%C3%A8ne

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Zirconium alloys used in the nuclear industry are exposed to extreme conditions undergoing high levels of irradiation damage and corrosion. Zircaloy-2 is used as nuclear fuel cladding in boiling water reactors and for the encapsulation of the spallation target in the neutron source SINQ at the Paul Scherrer Institute. As a result of oxidation, hydrogen is produced and partially taken up into the zirconium matrix. As the hydrogen reaches the solubility limit, it precipitates in the form of a zirconium hydride. A number of deleterious effects of hydrides have been extensively studied, including the embrittlement of the material and a unique cracking phenomenon, namely delayed hydride cracking (DHC). DHC occurs as hydrogen in solid solution diffuses towards locations of higher tensile stress, where it subsequently precipitates as the local solvus limit is reached. Once the hydride grows to a critical size, it fractures, which can continue to propagate in repeated steps by the same mechanism.Several studies have been performed in order to understand properties of DHC based on parameters like, alloy type, cracking temperature, hydrogen content, and cracking direction. The most important mechanical properties include the fracture toughness and cracking velocity, which governs the material failure conditions. Crystallographic properties have been investigated in order to understand how complex hydride precipitation develops within the context of DHC conditions. In this project, radial DHC is explored in irradiated and unirradiated thin-walled Zircaloy-2 nuclear fuel cladding with and without an inner liner, in addition to spallation target rod material. A unique three-point bending test, applicable also for irradiated samples in the hotlab, was developed to induce a consistent radially propagating outside-in crack. Results have provided insight into the effects of the inner liner on cracking velocity, showing correlations with the hydrogen depletion. The combined DHC and creep mechanisms, which cannot be decoupled, is coined as âcreep-delayed hydride crackingâ. As the initiating conditions for DHC are of great technical importance, the threshold stress intensity factor has been investigated, under ideal DHC conditions, where a minimum value occurs around 6 MPaâm. Quantitative analysis of the hydrogen distribution around the tip of an arrested DHC crack tip has been performed with neutron radiography at the SINQ. Trends show that the hydrogen concentration around the crack tip increases with temperature resulting likely from the larger hydrogen diffusion, and that the liner reduces the hydrogen available for DHC. Crystallographic analysis has provided insight on the hydride phases responsible for DHC with synchrotron micro X-ray diffraction, performed at the Swiss Light Source at PSI. The results directly suggest that the Î³-hydride is a stable phase precipitated at low temperatures. Testing of irradiated material provided insight into the crack initiation of DHC as a result of the strongly irregular outer surface generated from the oxidation. The propagation pattern is highly irregular compared to the unirradiated material due to the embrittled nature of the cladding from irradiation damage.

EPFL2022

Chargement

Study of hydrogen storage and compression

Nicolas Jean Matet

The goal of this rapport is to present an overview of the different hydrogen storage technologies, currently available for industrial application or at earlier stages of development. In order to identify the water and mechanical work requirements for compression of hydrogen, flow sheets of several compression process are realized. In order to decrease the work needed for hydrogen compression, realizing part of the compression with a metal-hydride compressor and integrating the compression process with a solar hydrogen production plant was study. It shows that metal-hydride pre-compression of hydrogen using waste heat before mechanical compression has the potential to lower the mechanical work consumption by about 15%compared to multi-stage mechanical compression alone.

2014

Chargement

Thermo-economic Evaluation of H2 synthesis from Biomass

Ivan Kostakev

The goal of this project would be to study the thermochemical production of hydrogen by using woody biomass as a raw material. The thermo-economic performance of the process will be evaluated and an optimisation will be performed to define the optimal system.

2009

Chargement

EPFL2022