Transmission, Distribution & Storage
Quantitative Evaluations of Hydrogen Diffusivity in V-X (X = Cr, Al, Pd) Alloy Membranes Based on Hydrogen Chemical Potential
Jan 2021
Publication
Vanadium (V) has higher hydrogen permeability than Pd-based alloy membranes but exhibits poor resistance to hydrogen-induced embrittlement. The alloy elements are added to reduce hydrogen solubility and prevent hydrogen-induced embrittlement. To enhance hydrogen permeability the alloy elements which improve hydrogen diffusivity in V are more suitable. In the present study hydrogen diffusivity in V-Cr V-Al and V-Pd alloy membranes was investigated in view of the hydrogen chemical potential and compared with the previously reported results of V-Fe alloy membranes. The additions of Cr and Fe to V improved the mobility of hydrogen atoms. In contrast those of Al and Pd decreased hydrogen diffusivity. The first principle calculations revealed that the hydrogen atoms cannot occupy the first-nearest neighbour T sites (T1 sites) of Al and Pd in the V crystal lattice. These blocking effects will be a dominant contributor to decreasing hydrogen diffusivity by the additions of Al and Pd. For V-based alloy membranes Fe and Cr are more suitable alloy elements compared with Al and Pd in view of hydrogen diffusivity.
Two-Stage Energy Management Strategies of Sustainable Wind-PV-Hydrogen-Storage Microgrid Based on Receding Horizon Optimization
Apr 2022
Publication
Hydrogen and renewable electricity-based microgrid is considered to be a promising way to reduce carbon emissions promote the consumption of renewable energies and improve the sustainability of the energy system. In view of the fact that the existing day-ahead optimal operation model ignores the uncertainties and fluctuations of renewable energies and loads a two-stage energy management model is proposed for the sustainable wind-PV-hydrogen-storage microgrid based on receding horizon optimization to eliminate the adverse effects of their uncertainties and fluctuations. In the first stage the day-ahead optimization is performed based on the predicted outpower of WT and PV the predicted demands of power and hydrogen loads. In the second stage the intra-day optimization is performed based on the actual data to trace the day-ahead operation schemes. Since the intra-day optimization can update the operation scheme based on the latest data of renewable energies and loads the proposed two-stage management model is effective in eliminating the uncertain factors and maintaining the stability of the whole system. Simulations show that the proposed two-stage energy management model is robust and effective in coordinating the operation of the wind-PV-hydrogen-storage microgrid and eliminating the uncertainties and fluctuations of WT PV and loads. In addition the battery storage can reduce the operation cost alleviate the fluctuations of the exchanged power with the power grid and improve the performance of the energy management model.
Effect of Hydrogen on the Tensile Behavior of Austenitic Stainless Steels 316L Produced by Laser-Powder Bed Fusion
Apr 2021
Publication
Hydrogen was doped in austenitic stainless steel (ASS) 316L tensile samples produced by the laser-powder bed fusion (L-PBF) technique. For this aim an electrochemical method was conducted under a high current density of 100 mA/cm2 for three days to examine its sustainability under extreme hydrogen environments at ambient temperatures. The chemical composition of the starting powders contained a high amount of Ni approximately 12.9 wt.% as a strong austenite stabilizer. The tensile tests disclosed that hydrogen charging caused a minor reduction in the elongation to failure (approximately 3.5% on average) and ultimate tensile strength (UTS; approximately 2.1% on average) of the samples using a low strain rate of 1.2 × 10−4 s−1. It was also found that an increase in the strain rate from 1.2 × 10−4 s−1 o 4.8 ×10−4 s−1 led to a reduction of approximately 3.6% on average for the elongation to failure and 1.7% on average for UTS in the pre-charged samples. No trace of martensite was detected in the X-ray diffraction (XRD) analysis of the fractured samples thanks to the high Ni content which caused a minor reduction in UTS × uniform elongation (UE) (GPa%) after the H charging. Considerable surface tearing was observed for the pre-charged sample after the tensile deformation. Additionally some cracks were observed to be independent of the melt pool boundaries indicating that such boundaries cannot necessarily act as a suitable area for the crack propagation.
The Techno-economics Potential of Hydrogen Interconnectors for Electrical Energy Transmission and Storage
Dec 2021
Publication
This research introduces a ‘Hydrogen Interconnector System’ (HIS) as a novel method 7 for transporting electrical energy over long distances. The system takes electricity from 8 stranded renewable energy assets converts it to hydrogen in an electrolyser plant transports 9 hydrogen to the demand centre via pipeline where it is reconverted to electricity in either a 10 gas turbine or fuel cell plant. This paper evaluates the competitiveness of the technology with 11 High Voltage Direct Current (HVDC) systems calculating the following techno-economic 12 indicators; Levelised Cost Of Electricity (LCOE) and Levelised Cost Of Storage (LCOS). The 13 results suggest that the LCOE of the HIS is competitive with HVDC for construction in 2050 14 with distance beyond 350km in case of all scenarios for a 1GW system. The LCOS is lower 15 than an HVDC system using large scale hydrogen storage in 6 out of 12 scenarios analysed 16 including for construction from 2025. The HIS was also applied to three case studies with 17 the results showing that the system outperforms HVDC from LCOS perspectives in all cases 18 and has 15-20% lower investment costs in 2 studies analysed.
Impact of Depth on Underground Hydrogen Storage Operations in Deep Aquifers
Mar 2024
Publication
Underground hydrogen storage in geological structures is considered appropriate for storing large amounts of hydrogen. Using the geological Konary structure in the deep saline aquifers an analysis of the influence of depth on hydrogen storage was carried out. Hydrogen injection and withdrawal modeling was performed using TOUGH2 software assuming different structure depths. Changes in the relevant parameters for the operation of an underground hydrogen storage facility including the amount of H2 injected in the initial filling period cushion gas working gas and average amount of extracted water are presented. The results showed that increasing the depth to approximately 1500 m positively affects hydrogen storage (flow rate of injected hydrogen total capacity and working gas). Below this depth the trend was reversed. The cushion gas-to-working gas ratio did not significantly change with increasing depth. Its magnitude depends on the length of the initial hydrogen filling period. An increase in the depth of hydrogen storage is associated with a greater amount of extracted water. Increasing the duration of the initial hydrogen filling period will reduce the water production but increase the cushion gas volume.
Complex Metal Hydrides for Hydrogen, Thermal and Electrochemical Energy Storage
Oct 2017
Publication
Hydrogen has a very diverse chemistry and reacts with most other elements to form compounds which have fascinating structures compositions and properties. Complex metal hydrides are a rapidly expanding class of materials approaching multi-functionality in particular within the energy storage field. This review illustrates that complex metal hydrides may store hydrogen in the solid state act as novel battery materials both as electrolytes and electrode materials or store solar heat in a more efficient manner as compared to traditional heat storage materials. Furthermore it is highlighted how complex metal hydrides may act in an integrated setup with a fuel cell. This review focuses on the unique properties of light element complex metal hydrides mainly based on boron nitrogen and aluminum e.g. metal borohydrides and metal alanates. Our hope is that this review can provide new inspiration to solve the great challenge of our time: efficient conversion and large-scale storage of renewable energy.
Catalytic Effect of MoS2 on Hydrogen Storage Thermodynamics and Kinetics of an As-milled YMg11Ni Alloy
Jul 2017
Publication
In this study YMg11Ni and YMg11Ni + 5 wt% MoS2 (named YMg11Ni–MoS2) alloys were prepared by mechanical milling to examine the effect of adding MoS2 on the hydrogen storage performance of a Y–Mg–Ni-based alloy. The as-cast and milled alloys were tested to identify their structures by X-ray diffraction and transmission electron microscopy. The isothermal hydrogen storage thermodynamics and dynamics were identified through an automatic Sieverts apparatus and the non-isothermal dehydrogenation performance was investigated by thermogravimetry and differential scanning calorimetry. The dehydrogenation activation energy was calculated by both Arrhenius and Kissinger methods. Results revealed that adding MoS2produces a very slight effect on hydrogen storage thermodynamics but causes an obvious reduction in the hydrogen sorption and desorption capacities because of the deadweight of MoS2. The addition of MoS2significantly enhances the dehydrogenation performance of the alloy such as lowering dehydrogenation temperature and enhancing dehydrogenation rate. Specifically the initial desorption temperature of the alloy hydride lowers from 549.8 K to 525.8 K. The time required to desorb hydrogen at 3 wt% H2 is 1106 456 363 and 180 s corresponding to hydrogen desorption temperatures at 593 613 633 and 653 K for the YMg11Ni alloy and 507 208 125 and 86 s at identical conditions for the YMg11Ni–5MoS2 alloy. The dehydrogenation activation energy (Ea) values with and without added MoS2are 85.32 and 98.01 kJ mol−1. Thus a decrease in Ea value by 12.69 kJ mol−1 occurs and is responsible for the amelioration of the hydrogen desorption dynamics by adding a MoS2 catalyst.
Hydrogen or Batteries for Grid Storage? A Net Energy Analysis
Apr 2015
Publication
Energy storage is a promising approach to address the challenge of intermittent generation from renewables on the electric grid. In this work we evaluate energy storage with a regenerative hydrogen fuel cell (RHFC) using net energy analysis. We examine the most widely installed RHFC configuration containing an alkaline water electrolyzer and a PEM fuel cell. To compare RHFC's to other storage technologies we use two energy return ratios: the electrical energy stored on invested (ESOIe) ratio (the ratio of electrical energy returned by the device over its lifetime to the electrical-equivalent energy required to build the device) and the overall energy efficiency (the ratio of electrical energy returned by the device over its lifetime to total lifetime electrical-equivalent energy input into the system). In our reference scenario the RHFC system has an ESOIeratio of 59 more favorable than the best battery technology available today (Li-ion ESOIe= 35). (In the reference scenario RHFC the alkaline electrolyzer is 70% efficient and has a stack lifetime of 100 000 h; the PEM fuel cell is 47% efficient and has a stack lifetime of 10 000 h; and the round-trip efficiency is 30%.) The ESOIe ratio of storage in hydrogen exceeds that of batteries because of the low energy cost of the materials required to store compressed hydrogen and the high energy cost of the materials required to store electric charge in a battery. However the low round-trip efficiency of a RHFC energy storage system results in very high energy costs during operation and a much lower overall energy efficiency than lithium ion batteries (0.30 for RHFC vs. 0.83 for lithium ion batteries). RHFC's represent an attractive investment of manufacturing energy to provide storage. On the other hand their round-trip efficiency must improve dramatically before they can offer the same overall energy efficiency as batteries which have round-trip efficiencies of 75–90%. One application of energy storage that illustrates the trade-off between these different aspects of energy performance is capturing overgeneration (spilled power) for later use during times of peak output from renewables. We quantify the relative energetic benefit of adding different types of energy storage to a renewable generating facility using [EROI]grid. Even with 30% round-trip efficiency RHFC storage achieves the same [EROI]grid as batteries when storing overgeneration from wind turbines because its high ESOIeratio and the high EROI of wind generation offset the low round-trip efficiency.
An Overview of the Recent Advances of Additive‐Improved Mg(BH4)2 for Solid‐State Hydrogen Storage Material
Jan 2022
Publication
Recently hydrogen (H2) has emerged as a superior energy carrier that has the potential to replace fossil fuel. However storing H2 under safe and operable conditions is still a challenging process due to the current commercial method i.e. H2 storage in a pressurised and liquified state which requires extremely high pressure and extremely low temperature. To solve this problem re‐ search on solid‐state H2 storage materials is being actively conducted. Among the solid‐state H2 storage materials borohydride is a potential candidate for H2 storage owing to its high gravimetric capacity (majority borohydride materials release >10 wt% of H2). Mg(BH4)2 which is included in the borohydride family shows promise as a good H2 storage material owing to its high gravimetric capacity (14.9 wt%). However its practical application is hindered by high thermal decomposition temperature (above 300 °C) slow sorption kinetics and poor reversibility. Currently the general research on the use of additives to enhance the H2 storage performance of Mg(BH4)2 is still under investigation. This article reviews the latest research on additive‐enhanced Mg(BH4)2 and its impact on the H2 storage performance. The future prospect and challenges in the development of additive‐ enhanced Mg(BH4)2 are also discussed in this review paper. To the best of our knowledge this is the first systematic review paper that focuses on the additive‐enhanced Mg(BH4)2 for solid‐state H2 storage.
SGN Aberdeen Vision Project: Final Report
May 2020
Publication
The Aberdeen Vision Project could deliver CO2 savings of 1.5MtCO2/y compared with natural gas. A dedicated pipeline from St Fergus to Aberdeen would enable the phased transfer of the Aberdeen regional gas distribution system to 20% then 100% hydrogen.
The study has demonstrated that 2% hydrogen can be injected into the National Transmission System (NTS) at St Fergus and its distribution through the system into the gas distribution network. Due to unique regional attributes the Aberdeen region could lead the UK in the conversion to largescale clean hydrogen. A 200MW hydrogen generation plant is planned to suit 2% blend into the NTS followed by a build out to supply the Aberdeen gas networks and to enable low cost hydrogen transport applications.
This report and any attachment is freely available on the ENA Smarter Networks Portal here. IGEM Members can download the report and any attachment directly by clicking on the pdf icon above.
The study has demonstrated that 2% hydrogen can be injected into the National Transmission System (NTS) at St Fergus and its distribution through the system into the gas distribution network. Due to unique regional attributes the Aberdeen region could lead the UK in the conversion to largescale clean hydrogen. A 200MW hydrogen generation plant is planned to suit 2% blend into the NTS followed by a build out to supply the Aberdeen gas networks and to enable low cost hydrogen transport applications.
This report and any attachment is freely available on the ENA Smarter Networks Portal here. IGEM Members can download the report and any attachment directly by clicking on the pdf icon above.
The Effect of Electrolytic Hydrogenation on Mechanical Properties of T92 Steel Weldments under Different PWHT Conditions
Aug 2020
Publication
In the present work the effects of electrolytic hydrogen charging of T92 steel weldments on their room-temperature tensile properties were investigated. Two circumferential weldments between the T92 grade tubes were produced by gas tungsten arc welding using the matching Thermanit MTS 616 filler material. The produced weldments were individually subjected to considerably differing post-welding heat treatment (PWHT) procedures. The first-produced weldment was conventionally tempered (i.e. short-term annealed below the Ac1 critical transformation temperature of the T92 steel) whereas the second one was subjected to its full renormalization (i.e. appropriate reaustenitization well above the T92 steel Ac3 critical transformation temperature and subsequent air cooling) followed by its conventional subcritical tempering. From both weldments cylindrical tensile specimens of cross-weld configuration were machined. The room-temperature tensile tests were performed for the individual welds’ PWHT states in both hydrogen-free and electrolytically hydrogen-charged conditions. The results indicated higher hydrogen embrittlement susceptibility for the renormalized-and-tempered weldments compared to the conventionally tempered ones. The obtained findings were correlated with performed microstructural and fractographic observations.
Hydrogen Uptake and Embrittlement of Carbon Steels in Various Environments
Aug 2020
Publication
To avoid failures due to hydrogen embrittlement it is important to know the amount of hydrogen absorbed by certain steel grades under service conditions. When a critical hydrogen content is reached the material properties begin to deteriorate. The hydrogen uptake and embrittlement of three different carbon steels (API 5CT L80 Type 1 P110 and 42CrMo4) was investigated in autoclave tests with hydrogen gas (H2) at elevated pressure and in ambient pressure tests with hydrogen sulfide (H2S). H2 gas with a pressure of up to 100 bar resulted in an overall low but still detectable hydrogen absorption which did not cause any substantial hydrogen embrittlement in specimens under a constant load of 90% of the specified minimum yield strength (SMYS). The amount of hydrogen absorbed under conditions with H2S was approximately one order of magnitude larger than under conditions with H2 gas. The high hydrogen content led to failures of the 42CrMo4 and P110 specimens.
Metallurgical Model of Diffusible Hydrogen and Non-Metallic Slag Inclusions in Underwater Wet Welding of High-Strength Steel
Nov 2020
Publication
High susceptibility to cold cracking induced by diffusible hydrogen and hydrogen embrittlement are major obstacles to greater utilization of underwater wet welding for high-strength steels. The aim of the research was to develop gas–slag systems for flux-cored wires that have high metallurgical activity in removal of hydrogen and hydroxyl groups. Thermodynamic modeling and experimental research confirmed that a decrease in the concentration of diffusible hydrogen can be achieved by reducing the partial pressure of hydrogen and water vapor in the vapor–gas bubble and by increasing the hydroxyl capacity of the slag system in metallurgical reactions leading to hydrogen fluoride formation and ionic dissolution of hydroxyl groups in the basic fluorine-containing slag of a TiO2–CaF2–Na3AlF6 system.
Research on the Concept of Hydrogen Supply Chains and Power Grids Powered by Renewable Energy Sources: A Scoping Review with the Use of Text Mining
Jan 2022
Publication
The key direction of political actions in the field of sustainable development of the energy sector and economy is the process of energy transformation (decarbonization) and increasing the share of renewable energy sources (RES) in the supply of primary energy. Regardless of the indisputable advantages RES are referred to as unstable energy sources. A possible solution might be the development of the concept of hydrogen supply chains especially the so-called green hydrogen obtained in the process of electrolysis from electricity produced from RES. The aim of the research undertaken in the article is to identify the scope of research carried out in the area of hydrogen supply chains and to link this research with the issues of the operation of electricity distribution networks powered by RES. As a result of the scoping review and the application of the text-mining method using the IRaMuTeQ tool which includes the analysis of the content of 12 review articles presenting the current research achievements in this field over the last three years (2016–2020) it was established that the issues related to hydrogen supply chains including green hydrogen are still not significantly associated with the problem of the operation of power grids. The results of the conducted research allow formulating recommendations for further research areas.
Optimal Operations for Hydrogen-based Energy Storage Systems in Wind Farms via Model Predictive Control
Feb 2021
Publication
Efficient energy production and consumption are fundamental points for reducing carbon emissions that influence climate change. Alternative resources such as renewable energy sources (RESs) used in electricity grids could reduce the environmental impact. Since RESs are inherently unreliable during the last decades the scientific community addressed research efforts to their integration with the main grid by means of properly designed energy storage systems (ESSs). In order to highlight the best performance from these hybrid systems proper design and operations are essential. The purpose of this paper is to present a so-called model predictive controller (MPC) for the optimal operations of grid-connected wind farms with hydrogen-based ESSs and local loads. Such MPC has been designed to take into account the operating and economical costs of the ESS the local load demand and the participation to the electricity market and further it enforces the fulfillment of the physical and the system's dynamics constraints. The dynamics of the hydrogen-based ESS have been modeled by means of the mixed-logic dynamic (MLD) framework in order to capture different behaviors according to the possible operating modes. The purpose is to provide a controller able to cope both with all the main physical and operating constraints of a hydrogen-based storage system including the switching among different modes such as ON OFF STAND-BY and at the same time reduce the management costs and increase the equipment lifesaving. The case study for this paper is a plant under development in the north Norway. Numerical analysis on the related plant data shows the effectiveness of the proposed strategy which manages the plant and commits the equipment so as to preserve the given constraints and save them from unnecessary commutation cycles.
Open-cathode PEMFC Heat Utilisation to Enhance Hydrogen Supply Rate of Metal Hydride Canisters
Mar 2019
Publication
In this paper the hydrogen supply to an open-cathode PEM fuel cell (FC) by using metal hydride (MH) storage and thermal coupling between these two components are investigated theoretically. One of the challenges in using MH hydrogen storage canisters is their limited hydrogen supply rate as the hydrogen release from MH is an endothermic reaction. Therefore in order to meet the required hydrogen supply rate high amounts of MH should be employed that usually suggests storage of hydrogen to be higher than necessary for the application adding to the size weight and cost of the system. On the other hand the exhaust heat (i.e. that is usually wasted if not utilised for this purpose) from open-cathode FCs is a low-grade heat. However this heat can be transferred to MH canisters through convection to heat them up and increase their hydrogen release rate. A mathematical model is used to simulate the heat transfer between PEMFC exhaust heat and MH storage. This enables the prediction of the required MH for different FC power levels with and without heat supply to the MH storage. A 2.5-kW open-cathode FC is used to measure the exhaust air temperature at different output powers. It was found that in the absence of heat supply from the FC to the MH canisters significantly higher number of MH canisters are required to achieve the required rate of hydrogen supply to the FC for sustained operation (specially at high power outputs). However using the exhaust hot air from the FC to supply heat to the MH storage can reduce the number of the MH canisters required by around 40% to 70% for power output levels ranging from 500 W to 2000 W.
Investigation of Mechanical Tests for Hydrogen Embrittlement in Automotive PHS Steels
Aug 2019
Publication
The problem of hydrogen embrittlement in ultra-high-strength steels is well known. In this study slow strain rate four-point bending and permeation tests were performed with the aim of characterizing innovative materials with an ultimate tensile strength higher than 1000 MPa. Hydrogen uptake in the case of automotive components can take place in many phases of the manufacturing process: during hot stamping due to the presence of moisture in the furnace atmosphere high-temperature dissociation giving rise to atomic hydrogen or also during electrochemical treatments such as cataphoresis. Moreover possible corrosive phenomena could be a source of hydrogen during an automobile’s life. This series of tests was performed here in order to characterize two press-hardened steels (PHS)—USIBOR 1500® and USIBOR 2000®—to establish a correlation between ultimate mechanical properties and critical hydrogen concentration.
Numerical Simulations of Cryogenic Hydrogen Cooling in Vortex Tubes with Smooth Transitions
Mar 2021
Publication
Improving efficiency of hydrogen cooling in cryogenic conditions is important for the wider applications of hydrogen energy systems. The approach investigated in this study is based on a Ranque-Hilsch vortex tube (RHVT) that generates temperature separation in a working fluid. The simplicity of RHVT is also a valuable characteristic for cryogenic systems. In the present work novel shapes of RHVT are computationally investigated with the goal to raise efficiency of the cooling process. Specifically a smooth transition is arranged between a vortex chamber where compressed gas is injected and the main tube with two exit ports at the tube ends. Flow simulations have been carried out using STAR-CCM+ software with the real-gas Redlich-Kwong model for hydrogen at temperatures near 70 K. It is determined that a vortex tube with a smooth transition of moderate size manifests about 7% improvement of the cooling efficiency when compared vortex tubes that use traditional vortex chambers with stepped transitions and a no-chamber setup with direct gas injection.
Pressurized Hydrogen from Charged Liquid Organic Hydrogen Carrier Systems by Electrochemical Hydrogen Compression
Feb 2021
Publication
We demonstrate that the combination of hydrogen release from a Liquid Organic Hydrogen Carrier (LOHC) system with electrochemical hydrogen compression (EHC) provides three decisive advantages over the state-of-the-art hydrogen provision from such storage system: a) The EHC device produces reduced hydrogen pressure on its suction side connected to the LOHC dehydrogenation unit thus shifting the thermodynamic equilibrium towards dehydrogenation and accelerating the hydrogen release; b) the EHC device compresses the hydrogen released from the carrier system thus producing high value compressed hydrogen; c) the EHC process is selective for proton transport and thus the process purifies hydrogen from impurities such as traces of methane. We demonstrate this combination for the production of compressed hydrogen (absolute pressure of 6 bar) from perhydro dibenzyltoluene at dehydrogenation temperatures down to 240 °C in a quality suitable for fuel cell operation e.g. in a fuel cell vehicle. The presented technology may be highly attractive for providing compressed hydrogen at future hydrogen filling stations that receive and store hydrogen in a LOHC-bound manner.
Hydrogen Permeation Studies of Composite Supported Alumina-carbon Molecular Sieves Membranes: Separation of Diluted Hydrogen from Mixtures with Methane
Jun 2020
Publication
One alternative for the storage and transport of hydrogen is blending a low amount of hydrogen (up to 15 or 20%) into existing natural gas grids. When demanded hydrogen can be then separated close to the end users using membranes. In this work composite alumina carbon molecular sieves membranes (Al-CMSM) supported on tubular porous alumina have been prepared and characterized. Single gas permeation studies showed that the H2/CH4 separation properties at 30 °C are well above the Robeson limit of polymeric membranes. H2 permeation studies of the H2–CH4 mixture gases containing 5–20% of H2 show that the H2 purity depends on the H2 content in the feed and the operating temperature. In the best scenario investigated in this work for samples containing 10% of H2 with an inlet pressure of 7.5 bar and permeated pressure of 0.01 bar at 30 °C the H2 purity obtained was 99.4%.
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