Spain

Metal hydrides are known as a potential efficient low-risk option for high-density hydrogen storage since the late 1970s. In this paper the present status and the future perspectives of the use of metal hydrides for hydrogen storage are discussed. Since the early 1990s interstitial metal hydrides are known as base materials for Ni – metal hydride rechargeable batteries. For hydrogen storage metal hydride systems have been developed in the 2010s [1] for us Read More

Hydrogen embrittlement susceptibility ratios calculated from slow strain rate tensile tests have been employed to study the response of three high-strength mooring steels in cold and warm synthetic seawater. The selected nominal testing temperatures have been 3 °C and 23 °C in order to resemble sea sites of offshore platform installation interest such as the North Sea and the Gulf of Mexico respectively. Three scenarios have been studied for each temp Read More

The aim of this work is to study the effect of the displacement rate on the hydrogen embrittlement of two different structural steels grades used in energetic applications. With this purpose samples were pre-charged with gaseous hydrogen at 19.5 MPa and 450 °C for 21 h. Then fracture tests of the pre-charged specimens were performed using different displacement rates. It is showed that the lower is the displacement rate and the largest is the steel stre Read More

The susceptibility of high strength ferritic steels to hydrogen-assisted fracture in hydrogen gas is usually evaluated by mechanical testing in high-pressure hydrogen gas or testing in air after pre-charging the specimens with hydrogen. We have used this second methodology conventionally known as internal hydrogen. Samples were pre-charged in an autoclave under 195 bar of pure hydrogen at 450ºC for 21 hours.Different chromium-molybdenum ste Read More

Progressive cold drawing in eutectoid steel produces a preferential orientation of pearlitic colonies and ferrite/cementite lamellae thus inducing strength anisotropy in the steel and mixed mode propagation. While in the hot rolled steel (not cold drawn) the pearlitic microstructure is randomly oriented and the crack progresses in hydrogen by breaking the ferrite/cementite lamellae in heavily drawn steels the pearlitic microstructure is fully oriented and t Read More

Stress corrosion cracking (SCC) of metals is an issue of major concern in engineering since this phenomenon causes many catastrophic failures of structural components in aggressive environments. SCC is even more harmful under cathodic conditions promoting the phenomenon known as hydrogen assisted cracking (HAC) hydrogen assisted fracture (HAF) or hydrogen embrittlement (HE). A common way to assess the susceptibility of a given material t Read More

Prestressing steel wires are highly susceptible to hydrogen embrittlement (HE). Residual stress-strain state produced after wire drawing plays an essential role since hydrogen damage at certain places of the material is directly affected by stress and strain fields. Changes in wire drawing conditions modify the stress and strain fields and consequently the HE susceptibility and life in service of these structural components in the presence of a hydrogenatin Read More

From a permeability and selectivity perspective supported thin-film Pd–Ag membranes are the best candidates for high-purity hydrogen recovery for methane-hydrogen mixtures from the natural gas grid. However the high hydrogen flux also results in induced bulk-to-membrane mass transfer limitations (concentration polarization) especially when working at low hydrogen concentration and high pressure which further reduces the hydrogen perme Read More

Mountain huts as special stand-alone micro-grid systems are not connected to a power grid and represent a burden on the environment. The micro-grid has to be flexible to cover daily and seasonal fluctuations. Heat and electricity are usually generated with fossil fuels due to the simple on-off operation. By introducing renewable energy sources (RESs) the generation of energy could be more sustainable but the generation and consumption must be b Read More

To limit the global temperature change to no more than 2 ◦C by reducing global emissions the European Union (EU) set up a goal of a 20% improvement on energy efficiency a 20% cut of greenhouse gas emissions and a 20% share of energy from renewable sources by 2020 (10% share of renewable energy (RE) specifically in the transport sector). By 2030 the goal is a 27% improvement in energy efficiency a 40% cut of greenhouse gas emissions and a 27 Read More

Considering a simple regenerative Brayton cycle the impact of using different fuel blends containing a variable volumetric percentage of hydrogen in methane was analysed. Due to the potential of hydrogen combustion in gas turbines to reduce the overall CO2 emissions and the dependency on natural gas further research is needed to understand the impact on the overall thermodynamic cycle. For that purpose a qualitative thermodynamic analysis Read More

This paper deals with the concept of micro-fracture map (MFM) and its role in structural integrity evaluations in materials science and engineering on the basis of previous research by the author on notch-induced fracture and hydrogen embrittlement of progressively cold drawn pearlitic steels and 316L austenitic stainless steel. With regard to this some examples are provided of assembly of MFMs in particular situations.

The Small Punch test has been recently used to estimate mechanical properties of steels in aggressive environments. This technique very interesting when there is shortage of material consists in using a small plane specimen and punch it until it fails. The type of tests normally used are under a constant load in an aggressive environment with the target to determine the threshold stress. However this is an inaccurate technique which takes time as the test Read More

Today in the field of energy the main goal is to reduce emissions with 7 the aim of maintaining a clean environment. To reduce energy consumption 8 from fossil fuels new tools for micro-grids have been proposed. In the context 9 of multi-vector energy management systems the present work proposes an 10 optimal scheduler based on genetic algorithms to manage flexible assets in the 11 energy system such as energy storage and manageable dema Read More

Variable renewable energy (VRE) has seen rapid growth in recent years. However VRE deployment requires a fleet of dispatchable power plants to supply electricity during periods with limited wind and sunlight. These plants will operate at reduced utilization rates that pose serious economic challenges. To address this challenge this paper presents the techno-economic assessment of flexible power and hydrogen production from integrated gasificati Read More

This edition of the Global Gas Report covers two very turbulent years in the global gas industry and the wider global energy markets. The Covid-19 pandemic lockdowns with a brief period of excess supply and low prices gave way to tight energy markets extreme price volatility and a compounding geopolitical challenge to energy security. At the time of writing the ongoing Russia-Ukraine conflict has been affecting the flows of gas and has put Europe on Read More

Whilst various new technologies for power generation are continuously being evaluated the owners of almost-new facilities such as combined-cycle gas turbine (CCGT) plants remain motivated to adapt these to new circumstances and avoid the balance-sheet financial impairments of underutilization. Not only are the owners reluctant to decommission the legacy CCGT assets but system operators value the inertia and flexibilities they contribute to a syste Read More

The exponentially growing contribution of renewable energy sources in the electricity mix requires large systems for energy storage to tackle resources intermittency. In this context the technologies for hydrogen production offer a clean and versatile alternative to boost renewables penetration and energy security. Hydrogen production as a strategy for the decarbonization of the energy sources mix has been investigated since the beginning of the 19 Read More

The way to decarbonization will be characterized by the huge production of hydrogen through sustainable routes. Thus the basic production way is water electrolysis sustained by renewable energy sources allowing for obtaining “green hydrogen”. The present paper reviews the main available technologies for the water electrolysis finalized to the hydrogen production. We describe the fundamental of water electrolysis and the problems related to purifica Read More

This research work presents an artificial intelligence approach to predicting the hydrogen concentration in the producer gas from biomass gasification. An experimental gasification plant consisting of an air-blown downdraft fixed-bed gasifier fueled with exhausted olive pomace pellets and a producer gas conditioning unit was used to collect the whole dataset. During an extensive experimental campaign the producer gas volumetric composition was Read More

The Poza de la Sal diapir is a closed circular depression with Cretaceous Mesozoic materials formed by gypsum Keuper clays and a large extension of salt in the center with intercalations of ophite. The low seismic activity of the area the reduced permeability and porosity of the salt caverns and the proximity to the Páramo de Poza wind park make it a suitable place for the construction of a facility for underground storage of green hydrogen obtained from sur Read More

In this work a novel reactor concept referred to as Membrane-Assisted Chemical Looping Reforming (MA-CLR) has been demonstrated at lab scale under different operating conditions for a total working time of about 100 h. This reactor combines the advantages of Chemical Looping such as CO2 capture and good thermal integration with membrane technology for a better process integration and direct product separation in a single unit which in its tur Read More

Green hydrogen—a carbon-free renewable fuel—has the capability to decarbonise a variety of sectors. The generation of green hydrogen is currently restricted to water electrolysers. The use of freshwater resources and critical raw materials however limits their use. Alternative water splitting methods for green hydrogen generation via photocatalysis and photoelectrocatalysis (PEC) have been explored in the past few decades; however their comme Read More

Turquoise hydrogen from natural gas pyrolysis has recently emerged as a promising alternative for low-carbon hydrogen production with a high-value pure carbon by-product. However the implications of this technology on the broader energy system are not well understood at present. To close this literature gap this study presents an assessment of the integration of natural gas pyrolysis into a simplified European energy system. The energy system model Read More

In recent years growing interest has emerged in investigating the integration of energy storage and green hydrogen production systems with renewable energy generators. These integrated systems address uncertainties related to renewable resource availability and electricity prices mitigating profit loss caused by forecasting errors. This paper focuses on the operation of a hybrid farm (HF) combining an alkaline electrolyzer (AEL) and a battery en Read More