Transmission, Distribution & Storage

The Isle of Grain (IoG) presents a technically feasible commercially viable strategic location to build and operate a hydrogen production facility which would be a key enabler to the UK meeting the Net Zero 2050 target.

As highlighted in the ‘Net Zero – The UK’s contribution to stopping global warming’ report published by The Committee on Climate Change in May 2019 hydrogen is set to have a major part to play in reducing UK carbon dioxide emissions. Carbon Capture and Storage (CCS) is also seen as essential to support those supplies.

The report further recognises that this will involve increased investments and that CCS and hydrogen will require both capital funding and revenue support.

For hydrogen to have a part to play in the decarbonisation of London and the south east of England a large-scale hydrogen production facility will be required which will provide a multi vector solution through the decarbonisation of the gas grid.

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The objective of this work was to enable the safe design of hydrogen pressure vessels by measuring the fatigue crack growth rates of ASME code-qualified steels in high-pressure hydrogen gas. While a design framework has recently been established for high-pressure hydrogen vessels a material property database does not exist to support the design calculations. This study addresses such voids in the database by measuring the fatigue crack growth rates of three different heats of ASME SA-372 Grade J steel in 100 MPa hydrogen gas. Results showed that the fatigue crack growth rates were similar for all three steel heats although the highest-strength steel appeared to exhibit the highest growth rates. Hydrogen accelerated the fatigue crack growth rates of the steels by as much as two orders of magnitude relative to anticipated crack growth rates in inert environments. Despite such dramatic effects of hydrogen on the fatigue crack growth rates measurement of these properties enables reliable definition of the design life of steel hydrogen containment vessels.

The liquid organic hydrogen carriers (LOHC) are aromatic molecules which can be considered as an attractive option for the storage and transport of hydrogen. A considerable amount of hydrogen up to 7–8% wt. can be loaded and unloaded with a reversible chemical reaction. Substituted quinolines and pyridines are available from petroleum coal processing and wood preservation or they can be synthesized from aniline. Quinolines and pyridines can be considered as potential LOHC systems provided they have favorable thermodynamic properties which were the focus of this current study. The absolute vapor pressures of methyl-quinolines were measured using the transpiration method. The standard molar enthalpies of vaporization of alkyl-substituted quinolines and pyridines were derived from the vapor pressure temperature dependencies. Thermodynamic data on vaporization and formation enthalpies available in the literature were collected evaluated and combined with our own experimental results. The theoretical standard molar gas-phase enthalpies of formation of quinolines and pyridines calculated using the quantum-chemical G4 methods agreed well with the evaluated experimental data. Reliable standard molar enthalpies of formation in the liquid phase were derived by combining high-level quantum chemistry values of gas-phase enthalpies of formation with experimentally determined enthalpies of vaporization. The liquid-phase hydrogenation/dehydrogenation reaction enthalpies of alkyl-substituted pyridines and quinolines were calculated and compared with the data for other potential liquid organic hydrogen carriers. The comparatively low enthalpies of reaction make these heteroaromatics a seminal LOHC system.

The UK has committed to significantly reduce greenhouse gas emissions by 2050 to help address climate change. Decarbonising heating is a key part of this and using hydrogen (H2) as a replacement to natural gas (NG) can help in achieving this. The objective of current research including HyDeploy is to demonstrate that NG containing levels of H2 beyond those currently allowed of 0.1 vol% (1000 ppm) [1] can be distributed and utilised safely and efficiently. Initial projects such as HyDeploy are studying the effects of introducing up to 20 vol% H2 in NG but later projects are considering using up to 100 vol% H2.

A key element in the safe operation of a modern gas distribution system is gas detection. However the addition of hydrogen to NG will alter the characteristics of the gas and the impact on gas detection must be considered. It is important that sensors remain sufficiently sensitive to the presence of hydrogen natural gas carbon monoxide (CO) and oxygen (O2) deficiency and that they don’t lead to false positive or false negative readings. The aim of this document is to provide a summary of the requirements for gas detection of hydrogen enriched natural gas for the gas distribution industry and other potentially interested parties. As such it is based on gas detectors presently used by the industry with the only major differences being the effects of hydrogen on the sensitivity of flammable gas sensors and the cross sensitivity of carbon monoxide gas sensors to hydrogen.

There is further information of gas detector concepts and technologies in the appendices.

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The UK government has committed to reducing greenhouse gas emissions to net zero by 2050. All future energy modelling identifies a key role for hydrogen (linked to CCUS) in providing decarbonised energy for heat transport industry and power generation. Blending hydrogen into the existing natural gas pipeline network has already been proposed as a means of transporting low carbon energy. However the expectation is that a gas blend with maximum hydrogen content of 20 mol% can be used without impacting consumers’ end use applications. Therefore a transitional solution is needed to achieve a 100% hydrogen future network.

Deblending (i.e. separation of the blended gas stream) is a potential solution to allow the existing gas transmission and distribution network infrastructure to transport energy as a blended gas stream. Deblending can provide either hydrogen natural gas or blended gas for space heating transport industry and power generation applications. If proven technically and economically feasible utilising the existing gas transmission and distribution networks in this manner could avoid the need for investment in separate gas and hydrogen pipeline networks during the transition to a future fully decarbonised gas network.

The Energy Network Association (ENA) “Gas Goes Green” programme identifies deblending could play a critical role in the transition to a decarbonised gas network. Gas separation technologies are well-established and mature and have been used and proven in natural gas processing for decades. However these technologies have not been used for bulk gas transportation in a transmission and distribution network setting. Some emerging hydrogen separation technologies are currently under development. The main hydrogen recovery and purification technologies currently deployed globally are:

• Cryogenic separation
• Membrane separation
• Pressure Swing Adsorption (PSA)

The technologies noted above require an energy input to drive the separation of gas components in the form of compression to provide a pressure differential. The configuration of the GB gas transmission and distribution networks provides a possible source of available energy through the pressure let-down in the network pressure tiers which could be used to drive the gas component separation processes. This study evaluated the gas separation technologies noted above against a selection of case studies based on actual network operating conditions to assess the technical andeconomic feasibility of hydrogen deblending in the GB gas network context. This study constitutes the first stage (proof of concept) in a programme of works that should provide the critical evidence for hydrogen deblending as a necessary component to enable the use of GB gas networks to transport and distribute hydrogen.

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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.

Recent research efforts to develop advanced–/ultrahigh–strength medium-Mn steels have led to the development of a variety of alloying concepts thermo-mechanical processing routes and microstructural variants for these steel grades. However certain grades of advanced–/ultrahigh–strength steels (A/UHSS) are known to be highly susceptible to hydrogen embrittlement due to their high strength levels. Hydrogen embrittlement characteristics of medium–Mn steels are less understood compared to other classes of A/UHSS such as high Mn twinning–induced plasticity steel because of the relatively short history of the development of this steel class and the complex nature of multiphase fine-grained microstructures that are present in medium–Mn steels. The motivation of this paper is to review the current understanding of the hydrogen embrittlement characteristics of medium or intermediate Mn (4 to 15 wt pct) multiphase steels and to address various alloying and processing strategies that are available to enhance the hydrogen-resistance of these steel grades.

Hydrogen embrittlement which severely affects structural materials such as steel comprises several mechanisms at the atomic level. One of them is hydrogen enhanced decohesion (HEDE) the phenomenon of H accumulation between cleavage planes where it reduces the interplanar cohesion. Grain boundaries are expected to play a significant role for HEDE since they act as trapping sites for hydrogen. To elucidate this mechanism we present the results of first-principles studies of the H effect on the cohesive strength of α-Fe single crystal (001) and (111) cleavage planes as well as on the Σ5(310)[001] and Σ3(112)[11¯0] symmetrical tilt grain boundaries. The calculated results show that within the studied range of concentrations the single crystal cleavage planes are much more sensitive to a change in H concentration than the grain boundaries. Since there are two main types of procedures to perform ab initio tensile tests different in whether or not to allow the relaxation of atomic positions which can affect the quantitative and qualitative results these methods are revisited to determine their effect on the predicted cohesive strength of segregated interfaces

National Grid (NG) needs to understand the implications that a hydrogen rich gas mix may have on the existing pipeline network. The primary network consists extensively of X52 steel pipe sections welded together using girth welds. Different welding specifications that have been used in the past 40 years and girth welds with different specifications may behave differently when coming into contact with hydrogen gas.

The aim of the flow loop test programme is to begin to evaluate the durability of pipeline materials in the context of future proofing of gas grid service where the gas mix may include a significant proportion of hydrogen. One specific objective is to investigate the resistance to hydrogen embrittlement of a conventional steel (X52) with commonly used girth welds. The primary concern is that the phenomenon of hydrogen embrittlement may cause unexpected or early failure mechanisms especially in older pipe sections with less stringent girth weld specifications.

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A quantitative risk analysis to a central pressurized storage tank for gaseous hydrogen has been performed to attend requirements of licensing procedures established by the State Environment Agency of São Paulo State Brazil. Gaseous hydrogen is used to feed the reactor to promote hydrogenation at the surfactant unit. HAZOP was the hazard identification technique selected. System components failures were defined by event and fault tree analysis. Quantitative risk analysis was complied to define the acceptability concepts on societal and individual risks required by the State Environmental Agency to approve the installation operation license. Acceptable levels to public society from the analysis were reached. Safety recommendations to the gaseous hydrogen central were proposed to assure minimization of risk to the near-by community operators environment and property.

Energy storage systems are required to address the fluctuating behaviour of variable renewable energy sources. The environmental sustainability of energy storage technologies should be carefully assessed together with their techno-economic feasibility. In this work an environmental analysis of a renewable hydrogen-based energy storage system has been performed making use of input parameters made available in the framework of the European REMOTE project. The analysis is applied to the case study of the Froan islands (Norway) which are representative of many other insular microgrid sites in northern Europe. The REMOTE solution is compared with other scenarios based on fossil fuels and submarine connections to the mainland grid. The highest climate impacts are found in the dieselbased configuration (1090.9 kgCO2eq/MWh) followed by the REMOTE system (148.2 kgCO2eq/MWh) and by the sea cable scenario (113.7 kgCO2eq/MWh). However the latter is biased by the very low carbon intensity of the Norwegian electricity. A sensitivity analysis is then performed on the length of the sea cable and on the CO2 emission intensity of electricity showing that local conditions have a strong impact on the results. The REMOTE system is also found to be the most cost-effective solution to provide electricity to the insular community. The in-depth and comparative (with reference to possible alternatives) assessment of the renewable hydrogen-based system aims to provide a comprehensive overview about the effectiveness and sustainability of these innovative solutions as a support for off-grid remote areas.

The review presented herein is regarding the stress corrosion cracking (SCC) phenomena of carbon steel pipelines affected by the corrosive electrolytes that comes from external (E) and internal (I) environments as well as the susceptibility and tensile stress on the SCC. Some useful tools are presented including essential aspects for determining and describing the E-SCC and I-SCC in oil and gas pipelines. Therefore this study aims to present a comprehensive and critical review of a brief experimental summary and a comparison of physicochemical mechanical and electrochemical data affecting external and internal SCC in carbon steel pipelines exposed to corrosive media have been conducted. The SCC hydrogen-induced cracking (HIC) hydrogen embrittlement and sulfide stress cracking (SSC) are attributed to the pH and to hydrogen becoming more corrosive by combining external and internal sources promoting cracking such as sulfide compounds acidic soils acidic atmospheric compounds hydrochloric acid sulfuric acid sodium hydroxide organic acids (acetic acid mainly) bacteria induced corrosion cathodic polarization among others. SCC growth is a reaction between the microstructural chemical and mechanical effects and it depends on the external and internal environmental sources promoting unpredictable cracks and fractures. In some cases E-SCC could be initiated by hydrogen that comes from the over-voltage during the cathodic protection processes. I-SCC could be activated by over-operating pressure and temperature at flowing media during the production gathering storage and transportation of wet hydrocarbons through pipelines. The mechanical properties related to I-SCC were higher in comparison with those reviewed by E-SCC suggesting that pipelines suffer more susceptibility to I-SCC. When a pipeline is designed the internal fluid being transported (changes of environments) and the external environment concerning SCC should be considered. This review offers a good starting point for newcomers into the field it is written as a tutorial and covers a large number of basic standards in the area.

Thermally sprayed aluminium (TSA) coatings provide protection to offshore steel structures without the use of external cathodic protection (CP) systems. These coatings provide sacrificial protection in the same way as a galvanic anode and thus hydrogen embrittlement (HE) becomes a major concern with the use of high strength steels. The effect of TSA on the HE of steel seems to remain largely unknown. Further the location of hydrogen in TSA-coated steel has not been explored. To address the above knowledge gap API 5L X80 and AISI 4137 steel coupons with and without TSA were prepared and the amount of hydrogen present in these steels when cathodically polarised to −1.1 V (Ag/AgCl) for 30 days in synthetic seawater was determined. One set of TSA-coated specimens was left at open circuit potential (OCP). The study indicates that the amount of hydrogen present in TSA-coated steel is ~100 times more than the amount found in uncoated steel and that the hydrogen seems to be largely localised in the TSA layer.

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.

In addition to carbon capture and storage efforts are also being focussed on using captured CO₂ both directly as a working fluid and in chemical conversion processes as a key strategy for mitigating climate change and achieving resource efficiency. These processes require large amounts of energy which should come from sustainable and ideally renewable sources. A strong value chain is required to support the production of valuable products from CO₂ . A value chain is a network of technologies and infrastructures (such as conversion transportation storage) along with its associated activities (such as sourcing raw materials processing logistics inventory management waste management) required to convert low-value resources to high-value products and energy services and deliver them to customers. A CO₂ value chain involves production of CO₂ (involving capture and purification) technologies that convert CO₂ and other materials into valuable products sourcing of low-carbon energy to drive all of the transformation processes required to convert CO₂ to products (including production of hydrogen syngas methane etc.) transport of energy and materials to where they are needed managing inventory levels of resources and delivering the products to customers all in order to create value (economic environmental social etc.).

Technologies underpinning future CO₂ value chains were examined. CO₂ conversion technologies such as urea production Sabatier synthesis Fischer-Tropsch synthesis hydrogenation to methanol dry reforming hydrogenation to formic acid and electrochemical reduction were assessed and compared based on key performance indicators such as: CAPEX OPEX electricity consumption TRL product price net CO₂ consumption etc. Technologies for transport and storage of key resources are also discussed. This work lays the foundation for a comprehensive whole-system value chain analysis modelling and optimisation.

A CsH and KH co-doped Mg(NH₂)₂/2LiH composite was prepared with a composition of Mg(NH₂)₂/2LiH–(0.08 − x)CsH–xKH and the hydrogen storage characteristics was systematically investigated. The results showed that the presence of KH further improved the reaction thermodynamics and kinetics of hydrogen storage in a CsH-containing Mg(NH₂)₂/2LiH system. A sample with 0.04 mol CsH and 0.04 mol KH had optimal hydrogen storage performance; its dehydrogenation could proceed at 130 °C and hydrogenation at 120 °C with 4.89 wt% of hydrogen storage capacity. At 130 °C a 25-fold increase in the dehydrogenation rate was achieved for the CsH and KH co-doped sample. More importantly the CsH and KH co-doped sample also had good cycling stability because more than 97% of the hydrogen storage capacity (4.34 wt%) remained for theMg(NH₂)₂/2LiH–0.04CsH–0.04KH sample after 30 cycles. A structural characterization revealed that added CsH and KH participated in the dehydrogenation and hydrogenation reactions by reversibly forming mixed amides of Li–K and Cs–Mg which caused the improved hydrogen storage thermodynamics and kinetics.

This paper has experimentally proved that hydrogen accumulates in large quantities in metal-ceramic and pocket electrodes of alkaline batteries during their operation. Hydrogen accumulates in the electrodes in an atomic form. After the release of hydrogen from the electrodes a powerful exothermic reaction of atomic hydrogen recombination with a large energy release occurs. This exothermic reaction is the cause of thermal runaway in alkaline batteries. For the KSL-15 battery the gravimetric capacity of sintered nickel matrix of the oxide-nickel electrode as hydrogen storage is 20.2 wt% and cadmium electrode is 11.5 wt%. The stored energy density in the metal-ceramic matrix of the oxide-nickel electrode of the battery KSL-15 is 44 kJ/g and in the cadmium electrode it is 25 kJ/g. The similar values for the KPL-14 battery are as follows. The gravimetric capacity of the active substance of the pocket oxide-nickel electrode as a hydrogen storage is 22 wt% and the cadmium electrode is 16.9 wt%. The density of the stored energy in the active substance oxide-nickel electrode is 48 kJ/g and in the active substance of the cadmium electrode it is 36.8 kJ/g. The obtained results of the accumulation of hydrogen energy in the electrodes by the electrochemical method are three times higher than any previously obtained results using the traditional thermochemical method.

Hydrogen gas pressure is an important test parameter when considering materials for high-pressure hydrogen applications. A large set of data on the effect of hydrogen gas pressure on mechanical properties in gaseous hydrogen experiments was reviewed. The data were analyzed by converting pressures into fugacities (f) and by fitting the data using an f|n| power law. For 95% of the data sets |n| was smaller than 0.37 which was discussed in the context of (i) rate-limiting steps in the hydrogen reaction chain and (ii) statistical aspects. This analysis might contribute to defining the appropriate test fugacities (pressures) to qualify materials for gaseous hydrogen applications.

The integration and control of energy systems for power generation consists of multiple heterogeneous subsystems such as chemical electrochemical and thermal and contains challenges that arise from the multi-way interactions due to complex dynamic responses among the involved subsystems. The main motivation of this work is to design the control system for an autonomous automated and sustainable system that meets a certain power demand profile. A systematic methodology for the integration and control of a hybrid system that converts liquefied petroleum gas (LPG) to hydrogen which is subsequently used to generate electrical power in a high-temperature fuel cell that charges a Li-Ion battery unit is presented. An advanced nonlinear model predictive control (NMPC) framework is implemented to achieve this goal. The operational objective is the satisfaction of power demand while maintaining operation within a safe region and ensuring thermal and chemical balance. The proposed NMPC framework based on experimentally validated models is evaluated through simulation for realistic operation scenarios that involve static and dynamic variations of the power load.

Expectations for energy storage are high but large-scale underground hydrogen storage in porous media (UHSP) remains largely untested. This article identifies and discusses the scientific challenges of hydrogen storage in porous media for safe and efficient large-scale energy storage to enable a global hydrogen economy. To facilitate hydrogen supply on the scales required for a zero-carbon future it must be stored in porous geological formations such as saline aquifers and depleted hydrocarbon reservoirs. Large-scale UHSP offers the much-needed capacity to balance inter-seasonal discrepancies between demand and supply decouple energy generation from demand and decarbonise heating and transport supporting decarbonisation of the entire energy system. Despite the vast opportunity provided by UHSP the maturity is considered low and as such UHSP is associated with several uncertainties and challenges. Here the safety and economic impacts triggered by poorly understood key processes are identified such as the formation of corrosive hydrogen sulfide gas hydrogen loss due to the activity of microbes or permeability changes due to geochemical interactions impacting on the predictability of hydrogen flow through porous media. The wide range of scientific challenges facing UHSP are outlined to improve procedures and workflows for the hydrogen storage cycle from site selection to storage site operation. Multidisciplinary research including reservoir engineering chemistry geology and microbiology more complex than required for CH₄ or CO₂ storage is required in order to implement the safe efficient and much needed large-scale commercial deployment of UHSP.

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 (ESOI_e) 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 ESOI_eratio of 59 more favorable than the best battery technology available today (Li-ion ESOI_e= 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 ESOI_eratio and the high EROI of wind generation offset the low round-trip efficiency.

Nanostructured Fe₇S₈ was successfully synthesized and its catalytic effect on hydrogen absorption/desorption performance of MgH₂2 is systemically discussed. The MgH₂ + 16.7 wt% Fe7S8 composite prepared by ball-milling method offers a striking catalytic activity for hydrogenation kinetics and also reduces the initial decomposition temperature for MgH₂2. The composite of MgH₂–Fe₇S₈ can absorb 4.000 wt% of hydrogen within 1800 s at 473 K which is about twice that of pristine MgH₂ (1.847 wt%) under the same conditions. The onset hydrogen release temperature of Fe₇S₈-modified MgH₂ is 420 K which is 290 K lower than that of additive-free MgH₂ (710 K). Meanwhile the doped sample could release 4.403 wt% of hydrogen within 1800 s at 623 K as compared to 2.479 wt% of hydrogen by MgH₂. The activation energy for MgH2–Fe7S8 is about 130.0 kJ mol−1 approximately 36 kJ mol−1 lower than that of MgH₂. The hydriding process of MgH2 + 16.7 wt% Fe₇S₈ follows the nucleation and growth mechanism. The prominent hydrogen storage performances are related to the reactions between MgH₂ and Fe₇S₈. The newly formed MgS and Fe in the ball-milling process present a co-catalytic effect on the hydrogen storage performance of MgH₂2.

As a promising hydrogen storage medium methanol has many advantages such as a high hydrogen content (12.5 wt%) and low-cost. However conventional methanol–water reforming methods usually require a high temperature (>200 °C). In this research we successfully designed an effective strategy to fully convert methanol to hydrogen for at least 1900 min (∼32 h) at near-room temperature. The strategy involves two main procedures which are CH₃OH →HCOOH → H₂ and CH₃OH → NADH → H₂. HCOOH and the reduced form of nicotinamide adenine dinucleotide (NADH) are simultaneously produced through the dehydrogenation of methanol by the cooperation of alcohol dehydrogenase (ADH) and aldehyde dehydrogenase (ALDH). Subsequently HCOOH is converted to H₂ by a new iridium polymer complex catalyst and an enzyme mimic is used to convert NADH to H₂ and nicotinamide adenine dinucleotide (NAD+). NAD+ can then be reconverted to NADH by repeating the dehydrogenation of methanol. This strategy and the catalysts invented in this research can also be applied to hydrogen production from other small organic molecules (e.g. ethanol) or biomass (e.g. glucose) and thus will have a high impact on hydrogen storage and applications.

The storage of hydrogen gas in underground lined rock caverns (LRCs) enables the implementation of the first fossil-free steelmaking process to meet the large demand for crude steel. Predicting the response of rock mass is important to ensure that gas leakage due to rupture of the steel lining does not occur. Analytical and numerical models can be used to estimate the rock mass response to high internal pressure; however the fitness of these models under different in situ stress conditions and cavern shapes has not been studied. In this paper the suitability of analytical and numerical models to estimate the maximum cavern wall tangential strain under high internal pressure is studied. The analytical model is derived in detail and finite element (FE) models considering both two-dimensional (2D) and three-dimensional (3D) geometries are presented. These models are verified with field measurements from the LRC in Skallen southwestern Sweden. The analytical model is inexpensive to implement and gives good results for isotropic in situ stress conditions and large cavern heights. For the case of anisotropic horizontal in situ stresses as the conditions in Skallen the 3D FE model is the best approach

The effect of different cathodic potentials applied to the X70 pipeline steel immersed in acidified and aerated synthetic soil solution under stress using a slow strain rate test (SSRT) and electrochemical impedance spectroscopy (EIS) was studied. According to SSRT results and the fracture surface analysis by scanning electron microscopy (SEM) the steel susceptibility to stress corrosion cracking (SCC) increased as the cathodic polarization increased (Ecp). This behavior is attributed to the anodic dissolution at the tip of the crack and the increment of the cathodic reaction (hydrogen evolution) producing hydrogen embrittlement. Nevertheless when the Ecp was subjected to the maximum cathodic potential applied (−970 mV) the susceptibility decreased; this behavior is attributed to the fact that the anodic dissolution was suppressed and the process of the SCC was dominated only by hydrogen embrittlement (HE). The EIS results showed that the cathodic process was influenced by the mass transport (hydrogen diffusion) due to the steel undergoing so many changes in the metallic surface as a result of the applied strain that it generated active sites at the surface.