France

Hydrogen sulfide (H₂S) is an important mediator of inflammatory processes. However controversial findings also exist and its underlying molecular mechanisms are largely unknown. Recently the byproducts of H₂S per-/polysulfides emerged as biological mediators themselves highlighting the complex chemistry of H₂S. In this study we characterized the biological effects of P* a slow-releasing H₂S and persulfide donor. To differentiate between H₂S and polysulfide-derived effects we decomposed P* into polysulfides. P* was further compared to the commonly used fast-releasing H₂S donor sodium hydrogen sulfide (NaHS). The effects on oxidative stress and interleukin-6 (IL-6) expression were assessed in ATDC5 cells using superoxide measurement qPCR ELISA and Western blotting. The findings on IL-6 expression were corroborated in primary chondrocytes from osteoarthritis patients. In ATDC5 cells P* not only induced the expression of the antioxidant enzyme heme oxygenase-1 via per-/polysulfides but also induced activation of Akt and p38 MAPK. NaHS and P* significantly impaired menadione-induced superoxide production. P* reduced IL-6 levels in both ATDC5 cells and primary chondrocytes dependent on H₂Srelease. Taken together P* provides a valuable research tool for the investigation of H₂S and per-/polysulfide signalling. These data demonstrate the importance of not only H₂S but also per-/polysulfides as bioactive signaling molecules with potent anti-inflammatory and in particular antioxidant properties.

A better understanding of chemical kinetics under volumetric expansion is important for a number of situations relevant to industrial safety including detonation diffraction and direct initiation reflected shock-ignition at obstacles ignition behind a decaying shock among others. The ignition of stoichiometric hydrogen-air mixtures was studied using 0D numerical simulations with time-dependent specific volume variations. The competition between chemical energy release and expansion-induced cooling was characterized for different cooling rates and mathematical forms describing the shock decay rate. The critical conditions for reaction quenching were systematically determined and the thermo-chemistry dynamics were analyzed near the critical conditions.

Hydrogen delivered at hydrogen refuelling station must be compliant with requirements stated in different standards which require specialized sampling device and personnel to operate it. Currently different strategies are implemented in different parts of the world and these strategies have already been used to perform 100s of hydrogen fuel sampling in USA EU and Japan. However these strategies have never been compared on a large systematic study. The purpose of this paper is to describe and compare the different strategies for sampling hydrogen at the nozzle and summarize the key aspects of all the existing hydrogen fuel sampling including discussion on material compatibility with the impurities that must be assessed. This review highlights the fact it is currently difficult to evaluate the impact or the difference these strategies would have on the hydrogen fuel quality assessment. Therefore comparative sampling studies are required to evaluate the equivalence between the different sampling strategies. This is the first step to support the standardization of hydrogen fuel sampling and to identify future research and development area for hydrogen fuel sampling.

With the clear adverse impacts of fossil fuel-based energy systems on the climate and environment ever-growing interest and rapid developments are taking place toward full or nearly full dependence on renewable energies in the next few decades. Estonia is a European country with large demands for electricity and thermal energy for district heating. Considering it as the case study this work explores the feasibility and full potential of optimally sized photovoltaic (PV) wind and PV/wind systems equipped with electric and thermal storage to fulfill those demands. Given the large excess energy from 100% renewable energy systems for an entire country this excess is utilized to first meet the district heating demand and then to produce hydrogen fuel. Using simplified models for PV and wind systems and considering polymer electrolyte membrane (PEM) electrolysis a genetic optimizer is employed for scanning Estonia for optimal installation sites of the three systems that maximize the fulfillment of the demand and the supply–demand matching while minimizing the cost of energy. The results demonstrate the feasibility of all systems fully covering the two demands while making a profit compared to selling the excess produced electricity directly. However the PV-driven system showed enormous required system capacity and amounts of excess energy with the limited solar resources in Estonia. The wind system showed relatively closer characteristics to the hybrid system but required a higher storage capacity by 75.77%. The hybrid PV/wind-driven system required a total capacity of 194 GW most of which belong to the wind system. It was also superior concerning the amount (15.05 × 109 tons) and cost (1.42 USD/kg) of the produced green hydrogen. With such full mapping of the installation capacities and techno-economic parameters of the three systems across the country this study can assist policymakers when planning different country-scale cogeneration systems.

Hydrogen (H2) is an essential vector for freeing our societies from fossil fuels and effectively initiating the energy transition. Offering high energy density hydrogen can be used for mobile stationary or industrial applications of all sizes. This perspective on the crucial role of hydrogen is shared by a growing number of countries worldwide (e.g. China Germany Japan Republic of Korea Australia and United States) which are publishing ambitious roadmaps for the development of hydrogen and fuel cell technologies supported by substantial financial efforts.

Proton exchange membrane (PEM) water electrolysis is one of the low temperature processes for producing green hydrogen when coupled with renewable energy sources. Although this technology has already reached a certain level of maturity and is being implemented at industrial scale its high capital expenditures deriving from the utilization of expensive corrosion-resistant materials limit its economic competitiveness compared to the widespread fossil fuel-based hydrogen production such as steam reforming. In particular the structural elements like bipolar plates (BPP) and porous transports layers (PTL) are essentially made of titanium protected by precious metal layers in order to withstand the harsh oxidizing conditions in the anode compartment. This review provides an analysis of literature on structural element degradation on the oxygen side of PEM water electrolyzers from the early investigations to the recent developments involving novel anti-corrosion coatings that protect more cost-effective BPP and PTL materials like stainless steels.

Gaseous hydrogen for fuel cell electric vehicles must meet quality standards such as ISO 14687:2019 which contains maximal control thresholds for several impurities which could damage the fuel cells or the infrastructure. A review of analytical techniques for impurities analysis has already been carried out by Murugan et al. in 2014. Similarly this document intends to review the sampling of hydrogen and the available analytical methods together with a survey of laboratories performing the analysis of hydrogen about the techniques being used. Most impurities are addressed however some of them are challenging especially the halogenated compounds since only some halogenated compounds are covered not all of them. The analysis of impurities following ISO 14687:2019 remains expensive and complex enhancing the need for further research in this area. Novel and promising analyzers have been developed which need to be validated according to ISO 21087:2019 requirements.

This paper reviews the relationship between the production of steel and the environment as it stands today. It deals with raw material issues (availability scarcity) energy resources and generation of by-products i.e. the circular economy the anthropogenic iron mine and the energy transition. The paper also deals with emissions to air (dust Particulate Matter heavy metals Persistant Organics Pollutants) water and soil i.e. with toxicity ecotoxicity epidemiology and health issues but also greenhouse gas emissions i.e. climate change. The loss of biodiversity is also mentioned. All these topics are analyzed with historical hindsight and the present understanding of their physics and chemistry is discussed stressing areas where knowledge is still lacking. In the face of all these issues technological solutions were sought to alleviate their effects: many areas are presently satisfactorily handled (the circular economy—a historical’ practice in the case of steel energy conservation air/water/soil emissions) and in line with present environmental regulations; on the other hand there are important hanging issues such as the generation of mine tailings (and tailings dam failures) the emissions of greenhouse gases (the steel industry plans to become carbon-neutral by 2050 at least in the EU) and the emission of fine PM which WHO correlates with premature deaths. Moreover present regulatory levels of emissions will necessarily become much stricter.

Flame propagation and acceleration in unobstructed channels/tubes is usually assumed as symmetric. A fully optically accessible narrow channel that allows to perform simultaneous high-speed schlieren visualization from two mutually perpendicular directions was built to asses the validity of the aforementioned assumption. Here we provide experimental evidence of the interesting three-dimensional structures and asymmetries that develop during the acceleration phase and show how these may control detonation onset in N2-diluted stoichiometric H2-O2 mixtures.

This article provides a techno-economic study on coupled offshore wind farm and green hydrogen production via sea water electrolysis (OWF-H2). Offshore wind energy wind farms (OWF) and water electrolysis (WE) technologies are described. MHyWind (the tool used to perform simulations and optimisations of such plants) is presented as well as the models of the main components in the study. Three case studies focus on offshore wind farms either stand-alone or connected to the grid via export cables coupled with a battery and electrolysis systems either offshore or onshore. Exhaustive searches and optimisations performed allowed for rules of thumb to be derived on the sizing of coupled OWF-H2 plants that minimize costs of hydrogen production (LCoH2 in €/kgH2): Non-connected OWF-H2 coupled to a battery offers the lowest LCoH2 without the costs of H2 transportation when compared to cases where the WE is installed onshore and connected to the OWF. Using a simple power distribution heuristic increasing the number of installed WE allows the system to take advantage of more OWF energy but doesn’t improve plant efficiency whereas a battery always does. Finally within the scope of this study it is observed that power ratios of optimized plant architectures (leading to the lowest LCoH2) are between 0.8-0.9 for PWE/POWF and 0.3-0.35 for PBattery/POWF.