Transmission, Distribution & Storage

This work is part of a project that aims to develop a micromechanics based damage law taking into account hydrogen assisted degradation. A 'vintage' API 5L X56N and a 'modern' API 5L X70M pipeline steel have been selected for this purpose. The paper focuses on an experimental calibration of ductile damage properties of the well known complete Gurson model for the two steels in absence of hydrogen. A basic microstructural characterization is provided showing a banded ferrite-pearlite microstructure for both steels. Charpy impact tests showed splits at the fracture surface for the X70 steel. Double-notched round bar tensile tests are performed aiming to provide the appropriate input for damage model calibration. The double-notched nature of the specimens allows to examine the material state at maximum load in the unfailed notch and the final material state in the failed notch. Different notch radii are used capturing a broad range of positive stress triaxialities. The notches are optically monitored for transverse necking in two perpendicular directions (transverse to rolling and through thickness) to reveal any anisotropy in plastic deformation and/or damage. It is explained how the occurrence of splits at the segregation zone and anisotropy complicate the calibration procedure. Calibration is done for each steel and acceptable results are obtained. However the occurrence of splits did not allow to evaluate the damage model for the highest levels of tested stress triaxiality.

Prestressing steel wires are manufactured by cold drawing during which a preferential orientation is achieved in the matter of pearlitic colonies and lamellae. In addition to this general trend special (unconventional) pearlitic pseudocolonies evolve during the heavy-drawing manufacture process affecting the posterior macro- micro- and nano-structural integrity of the material. This paper discusses the important role of such a special microstructural unit (the pearlitic pseudocolony) in the fracture process in air (inert) environment in the presence of crack-like defects as well as in the case of environmentally assisted cracking (stress corrosion cracking by localized anodic dissolution) or hydrogen embrittlement. Results clearly demonstrate the key role of pearlitic pseudocolonies in promoting crack deflection (and thus mixed-mode propagation) after a global mode I cracking especially in the case of fracture in air and stress corrosion cracking.

Strategic networks of hydrocarbon pipelines in long time service are adversely affected by the action of aggressive chemicals transported with the fluids and dissolved in the environment. Material degradation phenomena are amplified in the presence of hydrogen and water elements that increase the material brittleness and reduce the safety margins. The risk of failure during operation of these infrastructures can be reduced if not prevented by the continuous monitoring of the integrity of the pipe surfaces and by the tracking of the relevant bulk properties. A fast and potentially non-destructive diagnostic tool of material degradation which may be exploited in this context is based on the instrumented indentation tests that can be performed on metals at different scales. Preliminary validation studies of the significance of this methodology for the assessment of pipeline integrity have been carried out with the aid of interpretation models of the experiments. The main results of this ongoing activity are illustrated in this contribution.

In this paper we propose and verify a novel method to simulate crack propagation without propagating a crack by finite element method. We propose this method for elastoplastic analysis coupled with convection-diffusion. In the previous study we succeeded in performing elastoplastic analysis coupled with convection-diffusion of hydrogen for a material with a crack under tensile loading. This research extends the successful method to fatigue crack propagation. In convection-diffusion analysis in order to simulate the invasion and release of elements through the free surface the crack tip is expressed by using a notch with a sufficiently small radius. Therefore the node release method conventionally used to simulate crack propagation cannot be applied. Hence instead of crack propagation based on an analytical model we propose a novel method that can reproduce the influence of the vicinity of the crack tip on a crack. We moved the stress field near the crack tip in the direction opposite to that of crack propagation by an amount corresponding to the crack propagation length. When we extend the previous method to fatigue crack propagation simulation we must consider the difference in strain due to loading and unloading. This problem was solved by considering the strain due to loading as a displacement. Instead of moving the strain due to loading we moved the displacement. First we performed a simple tensile load analysis on the model and output the displacement of all the nodes of the model at maximum load. Then the displacement was moved in the direction opposite to that of crack propagation. Finally the stress field was reproduced by forcibly moving all the nodes by the displacement amount. The strain due to unloading was reproduced by removing the displacement. Furthermore we verified the equivalence of the crack propagation simulation and the proposed method.

As renewable energy sources are spreading the problems of energy usage transport and storage arise more frequently. In order that the performance of energy producing units from renewable sources which have a relatively low efficiency should not be decreased further and to promote sustainable energy consumption solutions a living lab conception was elaborated in this project. At the pilot site the produced energy (by PV panels gas turbines/engines) is stored in numerous ways including hydrogen production. The following uses of hydrogen are explored: (i) feeding it into the national natural gas network; (ii) selling it at a H-CNG (compressed natural gas) filling station; (iii) using it in fuel cells to produce electricity. This article introduces the overall implementation plan which can serve as a model for the hybrid energy communities to be established in the future.

Massive consumption of fossil fuel leads to shortage problems as well as various global environmental issues. Due to the global climatic problem in the world techniques to supply energy demand change from conventional methods that use fossil fuel as the energy source to clean and renewable sources such as solar and wind. However these renewable energy sources are not permanent. Energy storage methods can ensure to supply the energy demand in need if the energy is stored when the renewable source is available. Hydrogen is considered a promising alternative feedstock owing to has unique properties such as clean energy high energy density absence of toxic materials and carbon-free nature. Hydrogen is used main fuel source in fuel cells and hydrogen can be produced with various methods such as wind or electrolysis of water systems that supply electricity from renewable sources. However the safe effective and economical storage of hydrogen is still a challenge that limits the spread of the usage of hydrogen energy. High pressed hydrogen gas and cryogenic hydrogen liquid are two applied storage pathways although they do not meet the above-mentioned requirement. To overcome these drawbacks materials-based hydrogen storage materials have been mostly investigated research field recently. The aim of the study is that exhibiting various material-based hydrogen storage systems and development of these techniques worldwide. Additionally past and current status of the technology are explained and future perspective is discussed.

As part of the LTS Futures HyTechnical project IGEM requested that DNV GL undertake an assessment of the possible impact of hydrogen transmission on BPDs to support the development of supplements to the existing suite of natural gas standards to accommodate the possible future use of hydrogen. The current state of knowledge of the behaviour of large scale high pressure hydrogen releases is limited in comparison with the considerable body of data from research and operational experience of natural gas but is adequate to undertake an impact assessment to take account of the different gas outflow and fire characteristics of 100% hydrogen vs. natural gas.<br/>Calculations of the BPDs for 100% hydrogen pipeline fires on an equivalent basis to those in IGEM/TD/1 for natural gas have been performed with a degree of confidence in the results and demonstrated that the equivalent BPDs for 100% hydrogen are approximately 10% smaller than for natural gas. The results are presented graphically in this report.<br/>However hydrogen introduces the potential for substantially higher overpressures than natural gas due to the higher flame speed and wider flammable limits if delayed ignition is a credible event. The overpressure estimates presented in this report are intended to be scoping calculations to put the likely overpressures into context. The results suggest that significant overpressures are possible at the BPDs but there is a lack of evidence to support the estimation of the overpressures following delayed ignition of a large turbulent hydrogen release in the open (in contrast to explosions in confined or congested regions) and there is a high degree of uncertainty in the predictions presented here. It is therefore recommended that large scale pipeline rupture experiments are performed similar to those undertaken previously for hydrogen natural gas and natural gas/hydrogen mixtures but with ignition engineered to take place after a short delay in order to measure the overpressures and provide the means to validate or refine the predictions made.<br/>The analysis has highlighted limitations in the original method of calculating BPDs in IGEM/TD/1 which reflects the techniques available at the time approximately 40 years ago. Since then understanding of the hazards from pipeline failures and the ability to model the consequences and predict the associated risks to people in the surrounding area have advanced very considerably facilitated by software tools and documented in standards such as IGEM/TD/2. These methods allow the highly transient nature of a high pressure gas pipeline rupture release to be modelled more accurately and for the thermal effects of fires on people and buildings to be calculated taking account of the time-varying thermal dose.<br/>For these reasons a simple comparison of the possible overpressure effects of delayed ignition of a 100% hydrogen release at the BPDs can be misleading and implies that the overpressure hazards could be more severe than those for fires which may not be the case. Example calculations have been performed for a representative pipeline case which indicate that using current methods the predicted thermal hazard distances for 100% hydrogen pipeline fires (house burning and escape for people) are substantially greater than those estimated for overpressures following delayed ignition for similar levels of vulnerability. This report addresses buried pipelines only – the potential for more severe explosion overpressure effects for hydrogen releases may be more significant for Above Ground Installations (AGIs) especially where congestion or confinement may be present. It is recommended that similar studies are conducted to quantify the effect of hydrogen conversion on the consequences and risks associated with hydrogen releases at AGIs.<br/>Finally it is stressed that the analysis in this report does not consider the relative risks for 100% hydrogen and the equivalent natural gas pipelines. There remain uncertainties in the failure frequencies for steel pipelines transporting hydrogen and particularly the probability of immediate and delayed ignition. The likelihood of delayed ignition of a large turbulent high pressure hydrogen gas pipeline rupture release may be very low due to the wider flammability limits and lower minimum ignition energy for hydrogen compared with natural gas. Additional research is currently ongoing or planned to address the gaps in knowledge for 100% hydrogen which should allow more robust comparisons of the relative risks to be made in the future.

The UK oil and gas sector is mature and a combination of a dwindling resource base and a move towards decarbonisation has led to lower investments and an increasing decommissioning bill. Many existing offshore assets are in the vicinity of potential renewable energy developments or low-carbon facilities. We propose a technical evaluation process to understand whether pipelines might be repurposed to reduce the costs of low-carbon energy investment and oil decommissioning. We identify survival analysis as an effective method to investigate the potential of pipelines repurposing based on historical failure records as it deals with acceptable levels of data gaps and does not require associated field costs for detailed inspection. It provides a close estimate of the anticipated remaining life when compared to feasibility studies. We use survival analysis to examine several repurposing case studies for low-carbon investments. It also demonstrates that several pipeline systems have the potential to operate safely beyond their design life. Detailed records of failure will allow for further development of this methodology in the future.

The spinning process will lead to changes in the micro-structure and mechanical properties of the materials in different positions of the high-pressure hydrogen storage cylinder which will show different hydrogen embrittlement resistance in the high-pressure hydrogen environment. In order to fully study the safety of hydrogen storage in large-volume seamless steel cylinders this chapter associates the influence of the forming process with the deterioration of a high-pressure hydrogen cylinder (≥100 MPa). The anti-hydrogen embrittlement of SA-372 grade J steel at different locations of the formed cylinders was studied experimentally in three cylinders. The hydrogen embrittlement experiments were carried out according to method A of ISO 11114-4:2005. The relationship between tensile strength microstructure and hydrogen embrittlement is analyzed which provides comprehensive and reliable data for the safety of hydrogen storage and transmission.

Hydrogen is acknowledged as a potential and appealing energy carrier for decarbonizing the sectors that contribute to global warming such as power generation industries and transportation. Many people are interested in employing low-carbon sources of energy to produce hydrogen by using water electrolysis. Additionally the intermittency of renewable energy supplies such as wind and solar makes electricity generation less predictable potentially leading to power network incompatibilities. Hence hydrogen generation and storage can offer a solution by enhancing system flexibility. Hydrogen saved as compressed gas could be turned back into energy or utilized as a feedstock for manufacturing building heating and automobile fuel. This work identified many hydrogen production strategies storage methods and energy management strategies in the hybrid microgrid (HMG). This paper discusses a case study of a HMG system that uses hydrogen as one of the main energy sources together with a solar panel and wind turbine (WT). The bidirectional AC-DC converter (BAC) is designed for HMGs to maintain power and voltage balance between the DC and AC grids. This study offers a control approach based on an analysis of the BAC’s main circuit that not only accomplishes the function of bidirectional power conversion but also facilitates smooth renewable energy integration. While implementing the hydrogen-based HMG the developed control technique reduces the reactive power in linear and non-linear (NL) loads by 90.3% and 89.4%.

We consider a profit-maximizing renewable energy producer operating in a rural area with limited electricity distribution capacity to the grid. While maximizing profits the energy producer is responsible for the electricity supply of a local community that aims to be self-sufficient. Energy storage is required to deal with the energy productions' uncertain and intermittent character. A promising new solution is to use strategic hydrogen reserves. This provides a long-term storage option to deal with seasonal mismatches in energy production and the local community's demand. Using a Markov decision process we provide a model that determines optimal daily decisions on how much energy to store as hydrogen and buy or sell from the power grid. We explicitly consider the seasonality and uncertainty of production demand and electricity prices. We show that ignoring seasonal demand and production patterns is suboptimal and that introducing hydrogen storage transforms loss-making operations into profitable ones. Extensive numerical experiments show that the distribution capacity should not be too small to prevent local grid congestion. A higher storage capacity increases the number of buying actions from the grid thereby causing more congestion which is problematic for the grid operator. We conclude that a profit-maximizing hydrogen storage operation alone is not an alternative to grid expansion to solve congestion which is essential knowledge for policy-makers and grid operators.

This review article provides a comprehensive overview of the fundamentals modelling approaches experimental studies and challenges associated with hydrogen gas flow in pipelines. It elucidates key aspects of hydrogen gas flow including density compressibility factor and other relevant properties crucial for understanding its behavior in pipelines. Equations of state are discussed in detail highlighting their importance in accurately modeling hydrogen gas flow. In the subsequent sections one-dimensional and three-dimensional modelling techniques for gas distribution networks and localized flow involving critical components are explored. Emphasis is placed on transient flow friction losses and leakage characteristics shedding light on the complexities of hydrogen pipeline transportation. Experimental studies investigating hydrogen pipeline transportation dynamics are outlined focusing on the impact of leakage on surrounding environments and safety parameters. The challenges and solutions associated with repurposing natural gas pipelines for hydrogen transport are discussed along with the influence of pipeline material on hydrogen transportation. Identified research gaps underscore the need for further investigation into areas such as transient flow behavior leakage mitigation strategies and the development of advanced modelling techniques. Future perspectives address the growing demand for hydrogen as a clean energy carrier and the evolving landscape of hydrogen-based energy systems.

Hydrogen is a key enabler of a sustainable society. Refurbishment of the existing natural gas infrastructure for up to 100% H2 is considered one of the most energy- and resource-efficient energy transportation methods. The question remains whether the transportation of 100% H2 with reasonable adaptions of the infrastructure and comparable energy amounts to natural gas is possible. The well-known critical components for refurbishment such as increased compressor power reduced linepack as well as pipeline transport efficiencies and their influencing factors were considered based on thermodynamic calculations with a step-by-step overview. A H2 content of 20–30% results in comparable operation parameters to pure natural gas. In addition to transport in pipelines decentralized H2 production will also play an important role in addressing future demands.

Not only due to the energy crisis European policymakers are exploring options to substitute natural gas with renewable hydrogen. A condition for the application of hydrogen is a functioning transportation infrastructure. However the most efficient transport of large hydrogen quantities is still unclear and deeper analyses are missing. A promising option is converting the existing gas infrastructure. This study presents a novel approach to develop hydrogen networks by applying the Steiner tree algorithm to derive candidates and evaluate their costs. This method uses the existing grid (brownfield) and is compared to a newly built grid (Greenfield). The goal is the technical and economic evaluation and comparison of hydrogen network candidates. The methodology is applied to the German gas grid and demand and supply scenarios covering the industry heavy-duty transport power and heating sector imports and domestic production. Five brownfield candidates are compared to a greenfield candidate. The candidates differ by network length and pipeline diameters to consider the transported volume of hydrogen. The economic evaluation concludes that most brownfield candidates’ cost is significantly lower than those of the greenfield candidate. The candidates can serve as starting points for flow simulations and policymakers can estimate the cost based on the results.

In this work geochemical modelling using PhreeqC was carried out to evaluate the effects of geochemical reactions on the performance of underground hydrogen storage (UHS). Equilibrium exchange and mineral reactions were considered in the model. Moreover reaction kinetics were considered to evaluate the geochemical effect on underground hydrogen storage over an extended period of 30 years. The developed model was first validated against experimental data adopted from the published literature by comparing the modelling and literature values of H2 and CO2 solubility in water at varying conditions. Furthermore the effects of pressure temperature salinity and CO2% on the H2 and CO2 inventory and rock properties in a typical sandstone reservoir were evaluated over 30 years. Results show that H2 loss over 30 years is negligible (maximum 2%) through the studied range of conditions. The relative loss of CO2 is much more pronounced compared to H2 gas with losses of up to 72%. Therefore the role of CO2 as a cushion gas will be affected by the CO2 gas losses as time passes. Hence remedial CO2 gas injections should be considered to maintain the reservoir pressure throughout the injection and withdrawal processes. Moreover the relative volume of CO2 increases with the increase in temperature and decrease in pressure. Furthermore the reservoir rock properties porosity and permeability are affected by the underground hydrogen storage process and more specifically by the presence of CO2 gas. CO2 dissolves carbonate minerals inside the reservoir rock causing an increase in the rock’s porosity and permeability. Consequently the rock’s gas storage capacity and flow properties are enhanced

There exists no single optimal way for transporting hydrogen and other hydrogen carriers from one port to the other globally. Its delivery depends on several factors such as the quantity distance economics and the availability of the required infrastructure for its transportation. Europe has a strategy to invest in the production of green hydrogen in Africa to meet its needs. This study assessed the economic viability of shipping liquefied hydrogen (LH2 ) and hydrogen carriers to Germany from six African countries that have been identified as countries with great potential in the production of hydrogen. The results obtained suggest that the shipping of LH2 to Europe (Germany) will cost between 0.47 and 1.55 USD/kg H2 depending on the distance of travel for the ship. Similarly the transportation of hydrogen carriers could range from 0.19 to 0.55 USD/kg H2 for ammonia 0.25 to 0.77 USD/kg H2 for LNG 0.24 to 0.73 USD/kg H2 for methanol and 0.43 to 1.28 USD/kg H2 for liquid organic hydrogen carriers (LOHCs). Ammonia was found to be the ideal hydrogen carrier since it recorded the least transportation cost. A sensitivity analysis conducted indicates that an increase in the economic life by 5 years could averagely decrease the cost of LNG by some 13.9% NH3 by 13.2% methanol by 7.9% LOHC by 8.03% and LH2 by 12.41% under a constant distance of 6470 nautical miles. The study concludes with a suggestion that if both foreign and local participation in the development of the hydrogen market is increased in Africa the continent could supply LH2 and other hydrogen carriers to Europe at a cheaper price using clean fuel.

The mechanical properties of materials deteriorate when hydrogen embrittlement (HE) occurs seriously threatening the reliability and durability of the hydrogen system. Therefore it is important to summarize the status and development trends of research on HE. This study reviewed 6676 publications concerned with HE from 1997 to 2022 based on the Web of Science Core Collection. VOSviewer was used to conduct the bibliometric analysis and produce visualizations of the publications. The results showed that the number of publications on HE increased after 2007 especially between 2017 and 2019. Japan was the country with the highest numbers of productive authors and citations of publications and the total number of citations of Japanese publications was 24589. Kyushu University was the most influential university and the total number of citations of Kyushu University publications was 7999. Akiyama was the most prolific and influential author publishing 88 publications with a total of 2565 citations. The USA South Korea and some European countries are also leading in HE research; these countries have published more than 200 publications. It was also found that the HE publications generally covered five topics: “Hydrogen embrittlement in different materials” “Effect of hydrogen on mechanical properties of materials” “Effect of alloying elements or microstructure on hydrogen embrittlement” “Hydrogen transport” and “Characteristics and mechanisms of hydrogen related failures”. Research hotspots included “Fracture failure behavior and analysis” “Microstructure” “Hydrogen diffusion and transport” “Mechanical properties” “Hydrogen resistance” and so on. These covered the basic methods and purposes of HE research. Finally the distribution of the main subject categories of the publications was determined and these categories covered various topics and disciplines. This study establishes valuable reference information for the application and development of HE research and provides a convenient resource to help researchers and scholars understand the development trends and research directions in this field.

Compressed hydrogen storage is an energy-efficient alternative to liquefaction and in the absence of underground salt formations reservoirs like rock caverns mining shafts and cased boreholes are gaining traction. The limited reservoir volume constrained by excavation or drilling results in short high-pressure cycles. Thus effective temperature control is crucial to maintain integrity and maximize hydrogen density. This study presents a validated numerical model with open-access code for simulating heat exchange and predicting operating pressure and temperature for underground hydrogen storage in tanks or caverns. The validation encompasses analytical solutions and existing cylindrical models. Results highlight the heat transfer’s impact on hydrogen density and the limited penetration depth of the thermal perturbation underscoring the need for simulating heat transfer across multiple layers especially in restrictive media like cement. Managing injection and extraction flow rates is crucial to limit temperature peaks for larger radius reservoirs where heat transfer is less efficient.

Underground hydrogen storage in saline aquifers is a promising way to store large amounts of energy. Utilization of gas cushion enhances the deliverability of the storage and increases the volume of recovery gas. The key factor for the cushion characterization is cushion gas and storage gas mixing which can be used for simulation of mixing zone evolution. In this work coreflooding setup utilizing Raman spectroscopy is built and used for dispersion coefficient determination. Berea sandstone rock core is used as a test sample for setup validation and core entry/exit effects estimation. Dispersion for hydrogen and methane as displacing fluids is determined for 4 locations perspective for hydrogen storage in Poland is found. Reservoir structures most suitable for pure hydrogen or hydrogen/methane blend storage are selected.

A growing hydrogen economy requires new hydrogen distribution infrastructure to link geographically distributed hubs of supply and demand. The Hydrogen Optimization with Deployment of Infrastructure (HOwDI) Model helps meet this requirement. The model is a spatially resolved optimization framework that determines location-specific hydrogen production and distribution infrastructure to cost-optimally meet a specified location-based demand. While these results are useful in understanding hydrogen infrastructure development there is uncertainty in some costs that the model uses for inputs. Thus the project team took the modeling effort a step further and developed a Monte Carlo methodology to help manage uncertainties. Seven scenarios were run using existing infrastructure and new demand in Texas exploring different policy and tax approaches. The inclusion of tax credits increased the percentage of runs that could deliver hydrogen at <$4/kg from 31% to 77% and decreased the average dispensed cost from $4.35/kg to $3.55/kg. However even with tax credits there are still some runs where unabated SMR is deployed to meet new demand as the low-carbon production options are not competitive. Every scenario except for the zero-carbon scenario (without tax credits) resulted in at least 20% of the runs meeting the $4/kg dispensed fuel cost target. This indicates that multiple pathways exist to deliver $4/kg hydrogen.

The research and development of materials suitable for hydrogen storage has received a great deal of attention worldwide. Due to the safety risks involved in the conventional storage of hydrogen in its gaseous or liquid phase in containers and tanks development has focused on solid-phase hydrogen storage including metals. Light metal alloys and high-entropy alloys which have a high potential for hydrogen absorption/desorption at near-standard ambient conditions are receiving interest. For the development of these alloys due to the complexity of their compositions a computational approach using CALPHAD (Calculation of Phases Diagrams) and machine learning (ML) methods that exploit thermodynamic databases of already-known and experimentally verified systems are being increasingly applied. In order to increase the absorption capacity or to decrease the desorption temperature and to stabilize the phase composition specific material preparation methods (HEBM—high-energy milling HPT—high-pressure torsion) referred to as activation must be applied for some alloys.

Liquid Organic Hydrogen Carrier (LOHC) systems offer a very attractive way for storing and distributing hydrogen from electrolysis using excess energies from solar or wind power plants. In this contribution an alternative high-value utilization of such hydrogen is proposed namely its use in steady-state chemical hydrogenation processes. We here demonstrate that the hydrogen-rich form of the LOHC system dibenzyltoluene/perhydro-dibenzyltoluene can be directly applied as sole source of hydrogen in the hydrogenation of toluene a model reaction for large-scale technical hydrogenations. Equilibrium experiments using perhydro-dibenzyltoluene and toluene in a ratio of 1:3 (thus in a stoichiometric ratio with respect to H2) yield conversions above 60% corresponding to an equilibrium constant significantly higher than 1 under the applied conditions (270 °C).

This report was created to ensure a deeper understanding of the role and commercial viability of energy storage in enabling increasing levels of intermittent renewable power generation. It was specifically written to inform thought leaders and decision-makers about the potential contribution of storage in order to integrate renewable energy sources (RES) and about the actions required to ensure that storage is allowed to compete with the other flexibility options on a level playing field.<br/>The share of RES in the European electric power generation mix is expected to grow considerably constituting a significant contribution to the European Commission’s challenging targets to reduce greenhouse gas emissions. The share of RES production in electricity demand should reach about 36% by 2020 45-60% by 2030 and over 80% in 2050.<br/>In some scenarios up to 65% of EU power generation will be covered by solar photovoltaics (PV) as well as on- and offshore wind (variable renewable energy (VRE) sources) whose production is subject to both seasonal as well as hourly weather variability. This is a situation the power system has not coped with before. System flexibility needs which have historically been driven by variable demand patterns will increasingly be driven by supply variability as VRE penetration increases to very high levels (50% and more).<br/>Significant amounts of excess renewable energy (on the order of TWh) will start to emerge in countries across the EU with surpluses characterized by periods of high power output (GW) far in excess of demand. These periods will alternate with times when solar PV and wind are only generating at a fraction of their capacity and non-renewable generation capacity will be required.<br/>In addition the large intermittent power flows will put strain on the transmission and distribution network and make it more challenging to ensure that the electricity supply matches demand at all times.<br/>New systems and tools are required to ensure that this renewable energy is integrated into the power system effectively. There are four main options for providing the required flexibility to the power system: dispatchable generation transmission and distribution expansion demand side management and energy storage. All of these options have limitations and costs and none of them can solve the RES integration challenge alone. This report focuses on the question to what extent current and new storage technologies can contribute to integrate renewables in the long run and play additional roles in the short term.

Multiple-energy-fuelling stations which can supply several types of energy such as gasoline CNG and hydrogen could guarantee the efficient use of space. To guide the safety management of hybrid hydrogen–gasoline fuelling stations which utilize liquid hydrogen as an energy carrier the scale of gasoline pool fires was estimated using the hazard assessment tool Toxic Release Analysis of Chemical Emissions (TRACE). Subsequently the temperature and the stress due to temperature distribution were estimated using ANSYS. Based on the results the safety of liquid hydrogen storage tanks was discussed. It was inferred that the emissivity of the outer material of the tank and the safety distance between liquid hydrogen storage tanks and gasoline dispensers should be less than 0.2 and more than 8.5 m respectively to protect the liquid hydrogen storage tank from the gasoline pool fire. To reduce the safety distance several measures are required e.g. additional thermal shields such as protective intumescent paint and water sprinkler systems and an increased slope to lead gasoline off to a safe domain away from the liquid hydrogen storage tank

The recent advances on the effects of microstructural refinement and various nano-catalytic additives on the hydrogen storage properties of metal and complex hydrides obtained in the last few years in the allied laboratories at the University of Waterloo (Canada) and Military University of Technology (Warsaw Poland) are critically reviewed in this paper. The research results indicate that microstructural refinement (particle and grain size) induced by ball milling influences quite modestly the hydrogen storage properties of simple metal and complex metal hydrides. On the other hand the addition of nanometric elemental metals acting as potent catalysts and/or metal halide catalytic precursors brings about profound improvements in the hydrogen absorption/desorption kinetics for simple metal and complex metal hydrides alike. In general catalytic precursors react with the hydride matrix forming a metal salt and free nanometric or amorphous elemental metals/intermetallics which in turn act catalytically. However these catalysts change only kinetic properties i.e. the hydrogen absorption/desorption rate but they do not change thermodynamics (e.g. enthalpy change of hydrogen sorption reactions). It is shown that a complex metal hydride LiAlH4 after high energy ball milling with a nanometric Ni metal catalyst and/or MnCl2 catalytic precursor is able to desorb relatively large quantities of hydrogen at RT 40 and 80 °C. This kind of behavior is very encouraging for the future development of solid state hydrogen systems.