Hydrogen

17 pages, 935 KiB

Open AccessReview

Molecular Hydrogen as Medicine: An Assessment of Administration Methods

by Grace Russell, Alexander Nenov, Hesham Kisher and John T. Hancock

Hydrogen 2021, 2(4), 444-460; https://doi.org/10.3390/hydrogen2040025 - 25 Nov 2021

Cited by 14 | Viewed by 15682

Since the late 18th century, molecular hydrogen (H₂) has been shown to be well tolerated, firstly in animals, and then in humans. However, although research into the beneficial effects of molecular hydrogen in both plant and mammalian physiology is gaining momentum, the idea of utilising this electrochemically neutral and non-polar diatomic compound for the benefit of health has yet to be widely accepted by regulatory bodies worldwide. Due to the precise mechanisms of H₂ activity being as yet undefined, the lack of primary target identification, coupled with difficulties regarding administration methods (e.g., dosage and dosage frequencies, long-term effects of treatment, and the patient’s innate antioxidant profile), there is a requirement for H₂ research to evidence how it can reasonably and most effectively be incorporated into medical practice. This review collates and assesses the current information regarding the many routes of molecular hydrogen administration in animals and humans, whilst evaluating how targeted delivery methods could be integrated into a modern healthcare system. Full article

(This article belongs to the Special Issue Feature Papers in Hydrogen)

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16 pages, 2081 KiB

Open AccessReview

Solid-State Hydrogen Storage for a Decarbonized Society

by Claudio Pistidda

Hydrogen 2021, 2(4), 428-443; https://doi.org/10.3390/hydrogen2040024 - 20 Nov 2021

Cited by 34 | Viewed by 6749

Abstract

Humanity is confronted with one of the most significant challenges in its history. The excessive use of fossil fuel energy sources is causing extreme climate change, which threatens our way of life and poses huge social and technological problems. It is imperative to look for alternate energy sources that can replace environmentally destructive fossil fuels. In this scenario, hydrogen is seen as a potential energy vector capable of enabling the better and synergic exploitation of renewable energy sources. A brief review of the use of hydrogen as a tool for decarbonizing our society is given in this work. Special emphasis is placed on the possibility of storing hydrogen in solid-state form (in hydride species), on the potential fields of application of solid-state hydrogen storage, and on the technological challenges solid-state hydrogen storage faces. A potential approach to reduce the carbon footprint of hydrogen storage materials is presented in the concluding section of this paper. Full article

(This article belongs to the Special Issue Feature Papers in Hydrogen)

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14 pages, 6232 KiB

Open AccessArticle

Hydrogen Diffusivity in Different Microstructures of 42CrMo4 Steel

by Atif Imdad, Alfredo Zafra, Victor Arniella and Javier Belzunce

Hydrogen 2021, 2(4), 414-427; https://doi.org/10.3390/hydrogen2040023 - 3 Nov 2021

Cited by 5 | Viewed by 4260

Abstract

It is well known that the presence of hydrogen decreases the mechanical properties of ferritic steels, giving rise to the phenomenon known as hydrogen embrittlement (HE). The sensitivity to HE increases with the strength of the steel due to the increase of its microstructural defects (hydrogen traps), which eventually increase hydrogen solubility and decrease hydrogen diffusivity in the steel. The aim of this work is to study hydrogen diffusivity in a 42CrMo4 steel submitted to different heat treatments—annealing, normalizing and quench and tempering—to obtain different microstructures, with a broad range of hardness levels. Electrochemical hydrogen permeation tests were performed in a modified Devanathan and Stachursky double-cell. The build-up transient methodology allowed the determination of the apparent hydrogen diffusion coefficient, D_app, and assessment of its evolution during the progressive filling of the microstructural hydrogen traps. Consequently, the lattice hydrogen diffusion coefficient, D_L, was determined. Optical and scanning electron microscopy (SEM) were employed to examine the steel microstructures in order to understand their interaction with hydrogen atoms. In general, the results show that the permeation parameters are strongly related to the steel hardness, being less affected by the type of microstructure. Full article

(This article belongs to the Special Issue Feature Papers in Hydrogen)

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15 pages, 6165 KiB

Open AccessArticle

Hydrogen Sorption Properties of a Novel Refractory Ti-V-Zr-Nb-Mo High Entropy Alloy

by Anis Bouzidi, Laetitia Laversenne, Guilherme Zepon, Gavin Vaughan, Vivian Nassif and Claudia Zlotea

Hydrogen 2021, 2(4), 399-413; https://doi.org/10.3390/hydrogen2040022 - 27 Oct 2021

Cited by 14 | Viewed by 4284

Abstract

High entropy alloys belong to a new and promising class of functional materials for solid-state hydrogen storage. In this context, a novel single-phase body centered cubic (bcc) high entropy alloy Ti_0.30V_0.25Zr_0.10Nb_0.25Mo_0.10 was prepared. The physicochemical and hydrogen sorption properties have been determined by both laboratory and large-scale facilities. This alloy can quickly absorb hydrogen up to 2.0 H/M (2.8 wt.%) at room temperature and forms a face centered cubic (fcc) hydride, as proven by synchrotron X-ray diffraction. The Pressure–Composition Isotherm and in situ neutron diffraction during hydrogen/deuterium desorption reaction suggest that the alloy experiences a reversible single step phase transition (bcc↔fcc). PDF analysis from X-ray total scattering data points out that the hydride phase possesses an average fcc structure with random atoms distribution and small lattice distortion. Despite an initial small fading of the capacity, the alloy withstands 20 absorption/desorption cycling without phase decomposition, as demonstrated by kinetic measurements coupled with X-ray diffraction and microstructural study by SEM-EDS. Moreover, the complete hydrogen absorption occurs in less than 30 s at room temperature and the kinetic improves during cycling. Full article

(This article belongs to the Special Issue Feature Papers in Hydrogen)

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13 pages, 4715 KiB

Open AccessArticle

Performance of Hydrogen Storage Tanks of Type IV in a Fire: Effect of the State of Charge

by Sergii Kashkarov, Dmitriy Makarov and Vladimir Molkov

Hydrogen 2021, 2(4), 386-398; https://doi.org/10.3390/hydrogen2040021 - 23 Sep 2021

Cited by 10 | Viewed by 5822

Abstract

The use of hydrogen storage tanks at 100% of nominal working pressure (NWP) is expected only after refuelling. Driving between refuellings is characterised by the state of charge SoC <100%. There is experimental evidence that Type IV tanks tested in a fire at initial pressures below 1/3 NWP, leaked without rupture. This paper aims at understanding this phenomenon. The numerical research has demonstrated that the heat transfer from fire through the composite overwrap at storage pressures below NWP/3 is sufficient to melt the polymer liner. This melting initiates hydrogen microleaks through the composite before it loses the load-bearing ability. The fire-resistance rating (FRR) is defined as the time to rupture in a fire of a tank without or with blocked thermally activated pressure relief device. The dependence of a FRR on the SoC is demonstrated for the tanks with defined material properties and volumes in the range of 36–244 L. A composite wall thickness variation is shown to cause a safety issue by reducing the tank’s FRR and is suggested to be addressed by tank manufacturers and OEMs. The effect of a tank’s burst pressure ratio on the FRR is investigated. Thermal parameters of the composite wall, i.e., decomposition heat and temperatures, are shown in simulations of a tank failure in a fire to play an important role in its FRR. Full article

(This article belongs to the Special Issue Feature Papers in Hydrogen)

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Hydrogen, Volume 2, Issue 4 (December 2021) – 5 articles

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