Transmission, Distribution & Storage
Power to Hydrogen and Power to Water Using Wind Energy
May 2022
Publication
The need for energy and water security on islands has led to an increase in the use of wind power. However the intermittent nature of wind generation means it needs to be coupled with a storage system. Motivated by this two different models of surplus energy storage systems are investigated in this paper. In both models renewable wind energy is provided by a wind farm. In the first model a pumped hydro storage system (PHS) is used for surplus energy storage while in the second scenario a hybrid pumped hydrogen storage system (HPHS) is applied consisting of a PHS and a hydrogen storage system. The goal of this study is to compare the single and the hybrid storage system to fulfill the energy requirements of the island’s electricity load and desalination demands for domestic and irrigation water. The cost of energy (COE) is 0.287 EUR/kWh for PHS and 0.360 EUR/kWh for HPHS while the loss of load probability (LOLP) is 22.65% for PHS and 19.47% for HPHS. Sensitivity analysis shows that wind speed is the key parameter that most affects COE cost of water (COW) and LOLP indices while temperature affects the results the least.
A Perspective on Hydrogen Investment, Deployment and Cost Competitiveness
Feb 2021
Publication
Deployment and investments in hydrogen have accelerated rapidly in response to government commitments to deep decarbonisation establishing hydrogen as a key component in the energy transition.
To help guide regulators decision-makers and investors the Hydrogen Council collaborated with McKinsey & Company to release the report ‘Hydrogen Insights 2021: A Perspective on Hydrogen Investment Deployment and Cost Competitiveness’. The report offers a comprehensive perspective on market deployment around the world investment momentum as well as implications on cost competitiveness of hydrogen solutions.
The document can be downloaded from their website
To help guide regulators decision-makers and investors the Hydrogen Council collaborated with McKinsey & Company to release the report ‘Hydrogen Insights 2021: A Perspective on Hydrogen Investment Deployment and Cost Competitiveness’. The report offers a comprehensive perspective on market deployment around the world investment momentum as well as implications on cost competitiveness of hydrogen solutions.
The document can be downloaded from their website
Quantification of Temperature Dependence of Hydrogen Embrittlement in Pipeline Steel
Feb 2019
Publication
The effects of temperature on bulk hydrogen concentration and diffusion have been tested with the Devanathan–-Stachurski method. Thus a model based on hydrogen potential diffusivity loading frequency and hydrostatic stress distribution around crack tips was applied in order to quantify the temperature’s effect. The theoretical model was verified experimentally and confirmed a temperature threshold of 320 K to maximize the crack growth. The model suggests a nanoscale embrittlement mechanism which is generated by hydrogen atom delivery to the crack tip under fatigue loading and rationalized the ΔK dependence of traditional models. Hence this work could be applied to optimize operations that will prolong the life of the pipeline.
Absence of Spillover of Hydrogen Adsorbed on Small Palladium Clusters Anchored to Graphene Vacancies
May 2021
Publication
Experimental evidence exists for the enhancement of the hydrogen storage capacity of porous carbons when these materials are doped with metal nanoparticles. One of the most studied dopants is palladium. Dissociation of the hydrogen molecules and spillover of the H atoms towards the carbon substrate has been advocated as the reason for the enhancement of the storage capacity. We have investigated this mechanism by performing ab initio density functional molecular dynamics (AIMD) simulations of the deposition of molecular hydrogen on Pd6 clusters anchored on graphene vacancies. The clusters are initially near-saturated with atomic and molecular hydrogen. This condition would facilitate the occurrence of spillover since our energy calculations based on density functional theory indicate that migration of preadsorbed H atoms towards the graphene substrate becomes exothermic on Pd clusters with high hydrogen coverages. However AIMD simulations show that the H atoms prefer to intercalate and absorb within the Pd cluster rather than migrate to the carbon substrate. These results reveal that high activation barriers exist preventing the spillover of hydrogen from the anchored Pd clusters to the carbon substrate.
Dislocation and Twinning Behaviors in High Manganese Steels in Respect to Hydrogen and Aluminum Alloying
Dec 2018
Publication
The dislocation and twinning evolution behaviors in high manganese steels Fe-22Mn-0.6C and Fe-17Mn-1.5Al-0.6C have been investigated under tensile deformation with and without diffusive hydrogen. The notched tensile tests were interrupted once primary cracks were detected using the applied direct current potential drop measurement. In parallel the strain distribution in the vicinity of the crack was characterized by digital image correlation using GOM optical system. The microstructure surrounding the crack was investigated by electron backscatter diffraction. Electron channeling contrast imaging was applied to reveal the evolution of dislocations stacking faults and deformation twins with respect to the developed strain gradient and amount of hydrogen. The results show that the diffusive hydrogen at the level of 26 ppm has a conspicuous effect on initiating stacking faults twin bundles and activating multiple deformation twinning systems in Fe-22Mn-0.6C. Eventually the interactions between deformation twins and grain boundaries lead to grain boundary decohesion in this material. In comparison hydrogen does not obviously affect the microstructure evolution namely the twinning thickness and the amount of activated twinning systems in Fe-17Mn-1.5Al-0.6C. The Al-alloyed grade reveals a postponed nucleation of deformation twins delayed onset of the secondary twinning system and develops finer twinning lamellae in comparison to the Al-free material. These observations explain the improved resistance to hydrogen-induced cracking in Al-alloyed TWIP steels.
Ab Initio Study of the Combined Effects of Alloying Elements and H on Grain Boundary Cohesion in Ferritic Steels
Mar 2019
Publication
Hydrogen enhanced decohesion is expected to play a major role in ferritic steels especially at grain boundaries. Here we address the effects of some common alloying elements C V Cr and Mn on the H segregation behaviour and the decohesion mechanism at a Σ5(310)[001] 36.9∘ grain boundary in bcc Fe using spin polarized density functional theory calculations. We find that V Cr and Mn enhance grain boundary cohesion. Furthermore all elements have an influence on the segregation energies of the interstitial elements as well as on these elements’ impact on grain boundary cohesion. V slightly promotes segregation of the cohesion enhancing element C. However none of the elements increase the cohesion enhancing effect of C and reduce the detrimental effect of H on interfacial cohesion at the same time. At an interface which is co-segregated with C H and a substitutional element C and H show only weak interaction and the highest work of separation is obtained when the substitute is Mn.
Expert Opinion Analysis on Renewable Hydrogen Storage Systems Potential in Europe
Nov 2016
Publication
Among the several typologies of storage technologies mainly on different physical principles (mechanical electrical and chemical) hydrogen produced by power to gas (P2G) from renewable energy sources complies with chemical storage principle and is based on the conversion of electrical energy into chemical energy by means of the electrolysis of water which does not produce any toxic or climate-relevant emission. This paper aims to pinpoint the potential uses of renewable hydrogen storage systems in Europe analysing current and potential locations regulatory framework governments’ outlooks economic issues and available renewable energy amounts. The expert opinion survey already used in many research articles on different topics including energy has been selected as an effective method to produce realistic results. The obtained results highlight strategies and actions to optimize the storage of hydrogen produced by renewables to face varying electricity demand and generation-driven fluctuations reducing the negative effects of the increasing share of renewables in the energy mix of European Countries.
In Situ Formed Ultrafine Metallic Ni from Nickel (II) Acetylacetonate Precursor to Realize an Exceptional Hydrogen Storage Performance of MgH2–Ni-EG Nanocomposite
Dec 2021
Publication
It has been well known that doping nano-scale catalysts can significantly improve both the kinetics and reversible hydrogen storage capacity of MgH2. However so far it is still a challenge to directly synthesize ultrafine catalysts (e.g. < 5 nm) mainly because of the complicated chemical reaction processes. Here a facile one-step high-energy ball milling process is developed to in situ form ultrafine Ni nanoparticles from the nickel acetylacetonate precursor in the MgH2 matrix. With the combined action of ultrafine metallic Ni and expanded graphite (EG) the formed MgH2–Ni-EG nanocomposite with the optimized doping amounts of Ni and EG can still release 7.03 wt.% H2 within 8.5 min at 300 °C after 10 cycles. At a temperature close to room temperature (50 °C) it can also absorb 2.42 wt.% H2 within 1 h It can be confirmed from the microstructural characterization analysis that the in situ formed ultrafine metallic Ni is transformed into Mg2Ni/Mg2NiH4 in the subsequent hydrogen absorption and desorption cycles. It is calculated that the dehydrogenation activation energy of the MgH2–Ni-EG nanocomposite is also reduced obviously in comparison with the pure MgH2. Our work provides a methodology to significantly improve the hydrogen storage performance of MgH2 by combining the in situ formed and uniformly dispersed ultrafine metallic catalyst from the precursor and EG.
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%.
Fatigue Crack Growth in Operated Gas Pipeline Steels
Jun 2020
Publication
Regularities of fatigue crack growth for pipeline steels of different strength are presented and the changes in fatigue behavior of these steels after long term operation are analyzed. Threshold values of stress intensity factor range are lower for operated steels comparing to the corresponding values for as received ones. During the testing in the simulated soil solution NS4 a barely noticeable tendency to increase the threshold values of SIF was traced. It was explained by the appearance of intergranular fracture elements on the backgrownd of the typical flat fatigue relief already in the near-threshold region of fatigue crack growth curves in the soil solution. A higher relief of intergranular facets provided favorable conditions for occurrence of crack closure effect.<br/>Fatigue testing was performed using steel specimens after in-laboratory and in-service degradation and it was shown that results for both degraded steels are very close to each other proving the validity of the method of in-laboratory degradation. A new methodic approach to fatigue testing of pipe steels is presented which allows simulating working conditions of gas pipelines namely the hydrogen diffusion through the pipe wall to its external surface and estimating its possible effect on SCC. It consists in evaluation of the influence of hydrogen reached the crack tip only due to its diffusion on the crack growth. It is found that hydrogen absorbed by metal during the test providing such conditions causes a leap of crack growth rate in the Paris region of the fatigue crack growth curve of the tested 17H1S steel. Intergranular mechanism of fracture detected on the specimen fracture surface is suggested as a clear evidence of embrittlement of grain boundaries as a result of its hydrogenation.
A New Model For Hydrogen-Induced Crack (HIC) Growth in Metal Alloy Pipelines Under Extreme Pressure
Dec 2020
Publication
Pipeline failure caused by Hydrogen-Induced Cracking (HIC) also known as Hydrogen Embrittlement (HE) is a pressing issue for the oil and natural gas industry. Bursts in pipelines are devastating and extremely costly. The explosive force of a bursting pipe can inflict fatal injuries to workers while the combined loss of product and effort to repair are highly costly to producers. Further pipeline failures due to HIC have a long lasting impact on the surrounding environment. Safe use and operation of such pipelines depend on a good understanding of the underlying forces that cause HIC. Specifically a reliable way to predict the growth rate of hydrogen-induced cracks is needed to establish a safe duration of service for each length of pipeline. Pipes that have exceeded or are near the end of their service life can then be retired before the risk of HIC-related failures becomes too high. However little is known about the mechanisms that drive HIC. To date no model has been put forth that accurately predicts the growth rate of fractures due to HIC under extreme pressures such as in the context of natural gas and petroleum pipelines. Herein a mathematical model for the growth of fractures by HIC under extreme pressures is presented. This model is derived from first principles and the results are compared with other models. The implications of these findings are discussed and a description of future work based on these findings is presented.
Comparative Study of Battery Storage and Hydrogen Storage to Increase Photovoltaic Self-sufficiency in a Residential Building of Sweden
Dec 2016
Publication
Photovoltaic (PV) is promising to supply power for residential buildings. Battery is the most widely employed storage method to mitigate the intermittence of PV and to overcome the mismatch between production and load. Hydrogen storage is another promising method that it is suitable for long-term storage. This study focuses on the comparison of self-sufficiency ratio and cost performance between battery storage and hydrogen storage for a residential building in Sweden. The results show that battery storage is superior to the hydrogen storage in the studied case. Sensitivity study of the component cost within the hydrogen storage system is also carried out. Electrolyzer cost is the most sensitive factor for improving system performance. A hybrid battery and hydrogen storage system which can harness the advantages of both battery and hydrogen storages is proposed in the last place.
Recent Research Progress in Hybrid Photovoltaic–Regenerative Hydrogen Fuel Cell Microgrid Systems
May 2022
Publication
Hybrid photovoltaic–regenerative hydrogen fuel cell (PV-RHFC) microgrid systems are considered to have a high future potential in the effort to increase the renewable energy share in the form of solar PV technology with hydrogen generation storage and reutilization. The current study provides a comprehensive review of the recent research progress of hybrid PV-RHFC microgrid systems to extract conclusions on their characteristics and future prospects. The different components that can be integrated (PV modules electrolyzer and fuel cell stacks energy storage units power electronics and controllers) are analyzed in terms of available technology options. The main modeling and optimization methods and control strategies are discussed. Additionally various application options are provided which differentiate in terms of scale purpose and further integration with other power generating and energy storage technologies. Finally critical analysis and discussion of hybrid PV-RHFC microgrid systems were conducted based on their current status. Overall the commercialization of hybrid PV-RHFC microgrid systems requires a significant drop in the RHFC subsystem capital cost. In addition it will be necessary to produce complete hybrid PV-RHFC microgrid systems with integrated energy management control capabilities to avoid operational issues and ensure flexibility and reliability of the energy flow in relation to supply storage and demand.
Crack Size Dependency of Shear-mode Fatigue Threshold in Bearing Steel Subjected to Continuous Hydrogen Charging
Jun 2019
Publication
Premature delamination failure characterized by the white structure flaking (WSF) or the white etching crack (WEC) often occurs in rolling element bearings and it deteriorates the durability of bearing substantially. It is known that this failure is caused by shear-mode (Mode II and Mode III) crack growth in conjunction with evolution and invasion of hydrogen into material during operation. To ensure the structural integrity associated with rolling element bearing it is important to clarify the effect of hydrogen on the shear-mode fatigue crack growth behavior near the threshold level.<br/>In our previous study the effect of hydrogen on the shear-mode fatigue crack growth behavior in a bearing steel of JIS SUJ2 was examined near the threshold level. Consequently it was shown that the threshold stress intensity factor (SIF) range for shear-mode fatigue crack growth decreased significantly by action of hydrogen. However the investigation was made only for a crack with a surface length of about 900 mm. To thoroughly understand the critical condition for delamination failure it is important to investigate the crack size dependency of the threshold level for a shear-mode small fatigue crack in the presence of hydrogen. In the present study correspondingly the threshold SIF ranges for a shear-mode crack with different length were additionally measured in the same material by using a novel technique that enables continuous charging of hydrogen in a specimen during long-term fatigue test. Then a clear reduction in crack growth rate and a crack size dependency of the threshold SIF range were observed under the environmental condition of continuous hydrogen charging.
Analysis of Samples Cleaning Methods Prior to Hydrogen Content Determination in Steel
May 2020
Publication
There are multiple references to sample cleaning methods prior to hydrogen content determination or hydrogen spectroscopy analysis but there is still no unified criteria; different authors use their own “know-how” to perform this task. The aim of this paper is to solve or at least clarify this issue. In this work the most commonly used sample cleaning methods are compared. Then five different methodologies are applied on certified hydrogen content calibration pins and on high strength steel concrete-prestressing strands and the three main situations regarding hydrogen content in the microstructural net (non-charged charged and charged and uncharged) are studied. It was concluded that the HCl solution C-3.5 cleaning method recommended by ASTM G1 introduces large amounts of hydrogen in the samples; but can be useful for eliminating superficial oxides if necessary. The rest of the methods had similar results; but the more complete ones that involve ultrasounds and last longer than 8 min are not appropriated when important diffusion may occur on the samples during their application. Simple methods that involve acetone or trichloroethylene and last around 1 min are preferable for almost all situations as these are faster easier and cheaper. As a final recommendation as trichloroethylene is toxic the simple acetone method is in general the most convenient one for regular hydrogen content analysis.
A Fully Renewable and Efficient Backup Power System with a Hydrogen-biodiesel-fueled IC Engine
Jan 2019
Publication
Renewable energy is free abundant clean and could contribute towards a significant reduction of the global warming emissions. It is massively introduced as a source of electricity production across the globe and is expected to become the primary source of energy within the following decades. However despite the naturally replenished energy the supply is not always available. For this reason it is necessary at times of excess energy any surplus quantity to be sufficiently captured stored and later used when a deficit occurs. In this paper an overview of a backup power system operating with a hydrogen-biodiesel dual-fuel internal combustion engine is provided. The system is utilizing the organic chemical hydride method for safe hydrogen storage and transportation. The high energy content of hydrogen stored in the form of an organic hydride under ambient conditions makes it an ideal energy backup medium for large-scale and long-term applications. The research work focusses on the operation and emissions output of the dual-fuel internal combustion engine running on fully renewable fuels and the results are compared with the conventional petroleum-derived diesel engine. Biodiesel-hydrogen operation shows significant benefits in the reduction of carbon and soot emissions but deteriorates the NOx formation compared to the conventional diesel-powered engines. The operation of the engine at high loads can provide high exhaust thermal energy while alternative combustion strategies are necessary to be implemented at low load conditions for the optimum operation of the backup power system.
Evaluation of Blistered and Cold Deformed ULC Steel with Melt Extraction and Thermal Desorption Spectroscopy
Dec 2019
Publication
Hydrogen characterization techniques like melt extraction and thermal desorption spectroscopy (TDS) are useful tools in order to evaluate and understand the interaction between hydrogen and metals. These two techniques are used here on cold deformed ultra-low carbon (ULC) steel with and without hydrogen induced damage. The material is charged electrochemically in order to induce varying amounts of hydrogen and variable degrees of hydrogen induced damage. The aim of this work is to evaluate to which extent the hydrogen induced damage would manifest itself in melt extraction and TDS measurements.
Minimum Entropy Generation in a Heat Exchanger in the Cryogenic Part of the Hydrogen Liquefaction Process: On the Validity of Equipartition and Disappearance of the Highway
May 2019
Publication
Liquefaction of hydrogen is a promising technology for transporting large quantities of hydrogen across long distances. A key challenge is the high power consumption. In this work we discuss refrigeration strategies that give minimum entropy production/exergy destruction in a plate-fin heat exchanger that cools the hydrogen from 47.8 K to 29.3 K. Two reference cases are studied; one where the feed stream enters at 20 bar and one where it enters at 80 bar. Catalyst in the hot layers speeds up the conversion of ortho-to para-hydrogen. Optimal control theory is used to formulate a minimization problem where the objective function is the total entropy production the control variable is the temperature of the refrigerant and the constrains are the balance equations for energy mass and momentum in the hot layers. The optimal refrigeration strategies give a reduction of the total entropy production of 8.7% in the 20-bar case and 4.3% in the 80-bar case. The overall heat transfer coefficient and duty is higher in the 20 bar case which compensates for the increase in entropy production due to a thermal mismatch that is avoided in the 80 bar case. This leads the second law efficiency of the 20 bar case (91%) to be similar to the 80 bar case (89%). We demonstrate that equipartition of the entropy production and equipartition of the thermal driving force are both excellent design principles for the process unit considered with total entropy productions deviating only 0.2% and 0.5% from the state of minimum entropy production. Equipartition of the thermal driving force i.e. a constant difference between the inverse temperatures of the hot and cold layers represents a particularly simple guideline that works remarkably well. We find that both heat transfer and the spin-isomer reaction contribute significantly to the entropy production throughout the length of the process unit. Unlike previous examples in the literature the process unit considered in this work is not characterized by a “reaction mode” at the inlet followed by a “heat transfer mode”. Therefore it does not follow a highway in state space i.e. a band that is particularly dense with energy efficient solutions. By artificially increasing the spin-isomer conversion rate the highway appears when the conversion rate becomes sufficiently high.
Study on Early Business Cases for H2 In Energy Storage and More Broadly Power to H2 Applications
Jun 2017
Publication
Hydrogen is widely recognised as a promising option for storing large quantities of renewable electricity over longer periods. For that reason in an energy future where renewables are a dominant power source opportunities for Power to- Hydrogen in the long-term appear to be generally acknowledged. The key challenge today is to identify concrete short-term investment opportunities based on sound economics and robust business cases. The focus of this study is to identify these early business cases and to assess their potential replicability within the EU from now until 2025. An essential part and innovative approach of this study is the detailed analysis of the power sector including its transmission grid constraints.
Seasonal Energy Storage in Aluminium for 100 Percent Solar Heat and Electricity Supply
Sep 2019
Publication
In order to reduce anthropogenic global warming governments around the world have decided to reduce CO2 emissions from fossil fuels dramatically within the next decades. In moderate and cold climates large amounts of fossil fuels are used for space heating and domestic hot water production in winter. Although on an annual base solar energy is available in large quantities in these regions least of the solar resource is available in winter when most of the energy is needed. Therefore solutions are needed to store and transfer renewable energy from summer to winter. In this paper a seasonal energy storage based on the aluminium redox cycle (Al3+→Al→ Al3+) is proposed. For charging electricity from solar or other renewable sources is used to convert aluminium oxide or aluminium hydroxide to elementary aluminium (Al3+→Al). In the discharging process aluminium is oxidized (Al→Al3+) releasing hydrogen heat and aluminium hydroxide or aluminium oxide as a by-product. Hydrogen is used in a fuel cell to produce electricity. Heat produced from the aluminium oxidation process and by the fuel cell is used for domestic hot water production and space heating. The chemical reactions and energy balances are presented and simulation results are shown for a system that covers the entire energy demand for electricity space heating and domestic hot water of a new multi-family building with rooftop photovoltaic energy in combination with the seasonal Al energy storage cycle. It shows that 7–11 kWp of photovoltaic installations and 350–530 kg Al would be needed per apartment for different Swiss climates. Environmental life cycle data shows that the global warming potential and non-renewable primary energy consumption can be reduced significantly compared to today's common practice of heating with natural gas and using electricity from the ENTSO-E network. The presumptive cost were estimated and indicate a possible cost-competitiveness for this system in the near future.
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