Transmission, Distribution & Storage
Complex Metal Borohydrides: From Laboratory Oddities to Prime Candidates in Energy Storage Applications
Mar 2022
Publication
Despite being the lightest element in the periodic table hydrogen poses many risks regarding its production storage and transport but it is also the one element promising pollutionfree energy for the planet energy reliability and sustainability. Development of such novel materials conveying a hydrogen source face stringent scrutiny from both a scientific and a safety point of view: they are required to have a high hydrogen wt.% storage capacity must store hydrogen in a safe manner (i.e. by chemically binding it) and should exhibit controlled and preferably rapid absorption–desorption kinetics. Even the most advanced composites today face the difficult task of overcoming the harsh re-hydrogenation conditions (elevated temperature high hydrogen pressure). Traditionally the most utilized materials have been RMH (reactive metal hydrides) and complex metal borohydrides M(BH4 )x (M: main group or transition metal; x: valence of M) often along with metal amides or various additives serving as catalysts (Pd2+ Ti4+ etc.). Through destabilization (kinetic or thermodynamic) M(BH4 )x can effectively lower their dehydrogenation enthalpy providing for a faster reaction occurring at a lower temperature onset. The present review summarizes the recent scientific results on various metal borohydrides aiming to present the current state-of-the-art on such hydrogen storage materials while trying to analyze the pros and cons of each material regarding its thermodynamic and kinetic behavior in hydrogenation studies.
Hydrogen Carriers: Scientific Limits and Challenges for the Supply Chain, and Key Factors for Techno-Economic Analysis
Aug 2023
Publication
Hydrogen carriers are one of the keys to the success of using hydrogen as an energy vector. Indeed sustainable hydrogen production exploits the excess of renewable energy sources after which temporary storage is required. The conventional approaches to hydrogen storage and transport are compressed hydrogen (CH2 ) and liquefied hydrogen (LH2 ) which require severe operating conditions related to pressure (300–700 bar) and temperature (T < −252 ◦C) respectively. To overcome these issues which have hindered market penetration several alternatives have been proposed in the last few decades. In this review the most promising hydrogen carriers (ammonia methanol liquid organic hydrogen carriers and metal hydrides) have been considered and the main stages of their supply chain (production storage transportation H2 release and their recyclability) have been described and critically analyzed focusing on the latest results available in the literature the highlighting of which is our current concern. The last section reviews recent techno-economic analyses to drive the selection of hydrogen carrier systems and the main constraints that must be considered. The analyzed results show how the selection of H2 carriers is a multiparametric function and it depends on technological factors as well as international policies and regulations.
Techno-economic Assessment of Long-distance Supply Chains of Energy Carriers: Comparing Hydrogen and Iron for Carbon-free Electricity Generation
Mar 2023
Publication
The effective usage of renewable energy sources requires ways of storage and delivery to balance energy demand and availability divergences. Carbon-free chemical energy carriers are proposed solutions converting clean electricity into stable media for storage long-distance energy trade and on-demand electricity generation. Among them hydrogen (H2) is noteworthy being the subject of significant investment and research. Metal fuels such as iron (Fe) represent another promising solution for a clean energy supply but establishing an interconnected ecosystem still requires considerable research and development. This work proposes a model to assess the supply chain characteristics of hydrogen and iron as clean carbon-free energy carriers and then examines case studies of possible trade routes between the potential energy exporters Morocco Saudi Arabia and Australia and the energy importers Germany and Japan. The work comprises the assessment of economic (levelized cost of electricity - LCOE) energetic (thermodynamic efficiency) and environmental (CO2 emissions) aspects which are quantified by the comprehensive model accounting for the most critical processes in the supply chain. The assessment is complemented by sensitivity and uncertainty analyses to identify the main drivers for energy costs. Iron is shown to be lower-cost and more efficient to transport in longer routes and for long-term storage but potentially more expensive and less efficient than H2 to produce and convert. Uncertainties related to the supply chain specifications and the sensitivity to the used variables indicate that the path to viable energy carriers fundamentally depends on efficient synthesis conversion storage and transport. A break-even analysis demonstrated that clean energy carriers could be competitive with conventional energy carriers at low renewable energy prices while carbon taxes might be needed to level the playing field. Thereby green iron shows potential to become an important energy carrier for long-distance trade in a globalized clean energy market.
What is Stored, Why, and How? Mental Models, Knowledge, and Public Acceptance of Hydrogen Storage
Nov 2016
Publication
Although electricity storage plays a decisive role for the German “Energiewende” and it has become evident that the successful diffusion of technologies is not only a question of technical feasibility but also of social acceptance research on electricity storage technologies from a social science point of view is still scarce. This study therefore empirically explores laypersons’ mindsets and knowledge related to storage technologies focusing on hydrogen. While the results indicate overall supportive attitudes and trust in hydrogen storage some misconceptions a lack of information as well as concerns were identified which should be addressed in future communication concepts.
Leakage and Diffusion Characteristics of Underground Hydrogen Pipeline
Jun 2023
Publication
Soil corrosion and hydrogen embrittlement are the main factors of hydrogen pipeline failure. The gas escapes diffuses and accumulating in the soil and entering the atmosphere when leak occurs. The mechanism of gas diffusion in buried pipelines is very complicated. Mastering the evolution law of hydrogen leakage diffusion is conducive to quickly locating the leakage point and reducing the loss. The leakage model of the underground hydrogen pipeline is established in this paper. Effect of leakage hole soil type pipeline pressure pipeline diameter on hydrogen leakage diffusion were investigated. The results show that when the hydrogen pipeline leaks the hydrogen concentration increases with the increase of leakage time showing a symmetrical distribution trend. With the pipeline pressure increase hydrogen leakage speed is accelerated and longitudinal diffusion gradually becomes the dominant direction. With the leakage diameter increases hydrogen leakage per unit of time increases sharply. Hydrogen diffuses more easily in sandy soil and diffusion speed concentration and range are higher than that in clay soil. The research content provides a reference and basis for the detection and evaluation of buried hydrogen pipeline leakage.
OIES Podcast - Hydrogen Storage for a Net-zero Carbon Future
May 2023
Publication
In this podcast David Ledesma engages in a conversation with Alex Patonia and Rahmat Poudineh on their recent paper focusing on hydrogen storage for a net-zero carbon future. The podcast delves into the various types of hydrogen storage options highlighting their relative strengths and drawbacks.
In order for a hydrogen economy to be established several key factors must be addressed including efficient and decarbonized production adequate transportation infrastructure and the deployment of suitable hydrogen storage facilities. However hydrogen presents unique challenges when it comes to storage and handling. Due to its extremely low volumetric energy density under ambient conditions hydrogen cannot be efficiently or economically stored without undergoing compression liquefaction or conversion into other more manageable substances.
At present there exist several hydrogen storage solutions at different levels of technology market and commercial readiness each with varying applications depending on specific circumstances.
Additionally the podcast explores the primary barriers that hinder investment in hydrogen storage and the essential components of a viable business model that can address the primary risks to which potential hydrogen storage investors are exposed.
The podcast can be found on their website.
In order for a hydrogen economy to be established several key factors must be addressed including efficient and decarbonized production adequate transportation infrastructure and the deployment of suitable hydrogen storage facilities. However hydrogen presents unique challenges when it comes to storage and handling. Due to its extremely low volumetric energy density under ambient conditions hydrogen cannot be efficiently or economically stored without undergoing compression liquefaction or conversion into other more manageable substances.
At present there exist several hydrogen storage solutions at different levels of technology market and commercial readiness each with varying applications depending on specific circumstances.
Additionally the podcast explores the primary barriers that hinder investment in hydrogen storage and the essential components of a viable business model that can address the primary risks to which potential hydrogen storage investors are exposed.
The podcast can be found on their website.
A Bibliometric and Visualized Overview of Hydrogen Embrittlement from 1997 to 2022
Dec 2022
Publication
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.
Natural Iron Ores for Large-scale Thermochemical Hydrogen and Energy Storage
Jun 2022
Publication
A stable energy supply will require balancing the fluctuations of renewable energy generation due to the transition to renewable energy sources. Intraday and seasonal storage systems are often limited to local geographical or infrastructural circumstances. This study experimentally verifies the application of inexpensive and abundant natural iron ores for energy storage with combined hydrogen and heat release. The incorporated iron oxides are reduced with hydrogen from electrolysis to store energy in chemically bonded form. The on–demand reoxidation releases either pure hydrogen or high-temperature heat as valuable products. Natural iron ores as storage material are beneficial as the specific costs are lower by an order of magnitude compared to synthetic iron oxide-based materials. Suitable iron ores were tested in TG analysis and in a 1 kW fixed-bed reactor. Siderite a carbonate iron ore was verified as promising candidate as it shows significantly lower reaction temperatures and twice the storage capacity over other commercial iron ores such as ilmenite. The specific storage costs are as low as 80–150 $ per MWh hydrogen stored based on the experimental in-situ tests. The experimentally determined volumetric energy storage capacity for the bulk material was 1.7 and 1.8 MWh m− 3 for hydrogen and heat release respectively. The raw siderite ore was stable for over 50 consecutive cycles at operating temperatures of 500–600 ◦C in in-situ lifetime tests. The combination of high abundance low price and reasonable capacity can thus result in very low specific energy storage costs. The study proofs that suitable natural iron ores are an interesting economic solution for large-scale and seasonal energy storage systems.
A Bird’s-Eye View on Polymer-Based Hydrogen Carriers for Mobile Applications
Oct 2022
Publication
Globally reducing CO2 emissions is an urgent priority. The hydrogen economy is a system that offers long-term solutions for a secure energy future and the CO2 crisis. From hydrogen production to consumption storing systems are the foundation of a viable hydrogen economy. Each step has been the topic of intense research for decades; however the development of a viable safe and efficient strategy for the storage of hydrogen remains the most challenging one. Storing hydrogen in polymer-based carriers can realize a more compact and much safer approach that does not require high pressure and cryogenic temperature with the potential to reach the targets determined by the United States Department of Energy. This review highlights an outline of the major polymeric material groups that are capable of storing and releasing hydrogen reversibly. According to the hydrogen storage results there is no optimal hydrogen storage system for all stationary and automotive applications so far. Additionally a comparison is made between different polymeric carriers and relevant solid-state hydrogen carriers to better understand the amount of hydrogen that can be stored and released realistically.
Effect of the High-Pressure Hydrogen Gas Exposure in the Silica-Filled EPDM Sealing Composites with Different Silica Content
Mar 2022
Publication
With the increasing interest in hydrogen energy the stability of hydrogen storage facilities and components is emphasized. In this study we analyzed the effect of high-pressure hydrogen gas treatment in silica-filled EPDM composites with different silica contents. In detail cure characteristics crosslink density mechanical properties and hydrogen permeation properties were investigated. Results showed that material volume remaining hydrogen content and mechanical properties were changed after 96.3 MPa hydrogen gas exposure. With an increase in the silica content the crosslink density and mechanical properties increased but hydrogen permeability was decreased. After treatment high-silica-content composites showed lower volume change than low-silica-content composites. The crack damage due to the decompression caused a decrease in mechanical properties but high silica content can inhibit the reduction in mechanical properties. In particular EPDM/silica composites with a silica content of above 60 phr exhibited excellent resistance to hydrogen gas as no change in their physical and mechanical properties was observed.
Use of Existing Gas Infrastructure in European Hydrogen Economy
Apr 2023
Publication
The rapidly increasing production volume of clean hydrogen creates challenges for transport infrastructure. This study improves understanding of hydrogen transport options in Europe and provides more detailed analysis on the prospects for hydrogen transport in Finland. Previous studies and ongoing pipeline projects were reviewed to identify potential and barriers to hydrogen transport. A fatigue life assessment tool was built because material challenges have been one of the main concerns of hydrogen transportation. Many European countries aim at utilizing existing gas infrastructure for hydrogen. Conducted studies and pilot facilities have provided promising results. Hydrogen reduces the fatigue life of the pipeline but existing pipelines can be used for hydrogen if pressure variation is maintained at a reasonable level and the maximum operation pressure is limited. Moreover the use of existing pipelines can reduce hydrogen transport costs but the suitability of every pipeline for hydrogen must be analyzed and several issues such as leakage leakage detection effects of hydrogen on pipeline assets and end users corrosion maintenance and metering of gas flow must be considered. The development of hydrogen transport will vary within countries depending on the structure of the existing gas infrastructure and on the future hydrogen use profile.
Numerical Simulation of Hydrogen Diffusion in Cement Sheath of Wells Used for Underground Hydrogen Storage
Jul 2023
Publication
The negative environmental impact of carbon emissions from fossil fuels has promoted hydrogen utilization and storage in underground structures. Hydrogen leakage from storage structures through wells is a major concern due to the small hydrogen molecules that diffuse fast in the porous well cement sheath. The second-order parabolic partial differential equation describing the hydrogen diffusion in well cement was solved numerically using the finite difference method (FDM). The numerical model was verified with an analytical solution for an ideal case where the matrix and fluid have invariant properties. Sensitivity analyses with the model revealed several possibilities. Based on simulation studies and underlying assumptions such as non-dissolvable hydrogen gas in water present in the cement pore spaces constant hydrogen diffusion coefficient cement properties such as porosity and saturation etc. hydrogen should take about 7.5 days to fully penetrate a 35 cm cement sheath under expected well conditions. The relatively short duration for hydrogen breakthrough in the cement sheath is mainly due to the small molecule size and high hydrogen diffusivity. If the hydrogen reaches a vertical channel behind the casing a hydrogen leak from the well is soon expected. Also the simulation result reveals that hydrogen migration along the axial direction of the cement column from a storage reservoir to the top of a 50 m caprock is likely to occur in 500 years. Hydrogen diffusion into cement sheaths increases with increased cement porosity and diffusion coefficient and decreases with water saturation (and increases with hydrogen saturation). Hence cement with a low water-to-cement ratio to reduce water content and low cement porosity is desirable for completing hydrogen storage wells.
Derivation and Validation of a Reference Data-based Real Gas Model for Hydrogen
Mar 2023
Publication
Hydrogen plays an important role for the decarbonization of the energy sector. In its gaseous form it is stored at pressures of up to 1000 bar at which real gas effects become relevant. To capture these effects in numerical simulations accurate real gas models are required. In this work new correlation equations for relevant hydrogen properties are developed based on the Reference Fluid Thermodynamic and Transport Properties Database (REFPROP). Within the regarded temperature (150e400 K) and pressure (0.1e1000 bar) range this approach yields a substantially improved accuracy compared to other databased correlations. Furthermore the developed equations are validated in a numerical simulation of a critical flow Venturi nozzle. The results are in much better accordance with experimental data compared to a cubic equation of state model. In addition the simulation is even slightly faster.
Impact of Hydrogen Injection on Thermophysical Properties and Measurement Reliability in Natural Gas Networks
Oct 2021
Publication
In the context of the European decarbonization strategy hydrogen is a key energy carrier in the medium to long term. The main advantages deriving from a greater penetration of hydrogen into the energy mix consist in its intrinsic characteristics of flexibility and integrability with alternative technologies for the production and consumption of energy. In particular hydrogen allows to: i) decarbonise end uses since it is a zero-emission energy carrier and can be produced with processes characterized by the absence of greenhouse gases emissions (e.g. water electrolysis); ii) help to balancing electricity grid supporting the integration of non-programmable renewable energy sources; iii) exploit the natural gas transmission and distribution networks as storage systems in overproduction periods. However the hydrogen injection into the natural gas infrastructures directly influences thermophysical properties of the gas mixture itself such as density calorific value Wobbe index speed of sound etc [1]. The change of the thermophysical properties of gaseous mixture in turn directly affects the end use service in terms of efficiency and safety as well as the metrological performance and reliability of the volume and gas quality measurement systems. In this paper the authors present the results of a study about the impact of hydrogen injection on the properties of the natural gas mixture. In detail the changes of the thermodynamic properties of the gaseous mixtures with different hydrogen content have been analysed. Moreover the theoretical effects of the aforementioned variations on the accuracy of the compressibility factor measurement have been also assessed.
Comparative Techno-economic Analysis of Large-scale Renewable Energy Storage Technologies
Jun 2023
Publication
Energy storage is an effective way to address the instability of renewable energy generation modes such as wind and solar which are projected to play an important role in the sustainable and low-carbon society. Economics and carbon emissions are important indicators that should be thoroughly considered for evaluating the feasibility of energy storage technologies (ESTs). In this study we study two promising routes for large-scale renewable energy storage electrochemical energy storage (EES) and hydrogen energy storage (HES) via technical analysis of the ESTs. The levelized cost of storage (LCOS) carbon emissions and uncertainty assessments for EESs and HESs over the life cycle are conducted with full consideration of the critical links for these routes. In order to reduce the evaluation error we use the Monte Carlo method to derive a large number of data for estimating the economy and carbon emission level of ESTs based on the collected data. The results show that lithium ion (Li-ion) batteries show the lowest LCOS and carbon emissions at 0.314 US$ kWh-1 and 72.76 gCO2e kWh-1 compared with other batteries for EES. Different HES routes meaning different combinations of hydrogen production delivery and refueling methods show substantial differences in economics and the lowest LCOS and carbon emissions at 0.227 US$ kWh-1 and 61.63 gCO2e kWh-1 are achieved using HES routes that involve hydrogen production by alkaline electrolyzer (AE) delivery by hydrogen pipeline and corresponding refueling. The findings of this study suggest that HES and EES have comparable levels of economics and carbon emissions that should be both considered for large-scale renewable energy storage to achieve future decarbonization goals.
Hybrid Energy System Model in Matlab/Simulink Based on Solar Energy, Lithium‐Ion Battery and Hydrogen
Mar 2022
Publication
In this work a model of an energy system based on photovoltaics as the main energy source and a hybrid energy storage consisting of a short‐term lithium‐ion battery and hydrogen as the long‐term storage facility is presented. The electrical and the heat energy circuits and resulting flows have been modelled. Therefore the waste heat produced by the electrolyser and the fuel cell have been considered and a heat pump was considered to cover the residual heat demand. The model is designed for the analysis of a whole year energy flow by using a time series of loads weather and heat profile as input. This paper provides the main set of equations to derive the component properties and describes the implementation into MATLAB/Simulink. The novel model was created for an energy flow simulation over one year. The results of the simulation have been verified by comparing them with well‐established simulation results from HOMER Energy. It turns out that the novel model is well suited for the analysis of the dynamic system behaviour. Moreover different characteristics to achieve an energy balance an ideal dimensioning for the particular use case and further research possibilities of hydrogen use in the residential sector are covered by the novel model.
A Technical Evaluation to Analyse of Potential Repurposing of Submarine Pipelines for Hydrogen and CCS Using Survival Analysis
Oct 2022
Publication
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.
A Study of Hydrogen Embrittlement of SA-372 J Class High Pressure Hydrogen Storage Seamless Cylinder (≥100 MPA)
Nov 2022
Publication
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.
Mechanistic Evaluation of the Reservoir Engineering Performance for the Underground Hydrogen Storage in a Deep North Sea Aquifer
Jul 2023
Publication
Underground hydrogen storage (UHS) in aquifers salt caverns and depleted hydrocarbon reservoirs allows for the storage of larger volumes of H2 compared to surface storage in vessels. In this work we investigate the impact of aquifer-related mechanisms and parameters on the performance of UHS in an associated North Sea aquifer using 3D numerical compositional simulations. Simulation results revealed that the aquifer's permeability heterogeneity has a significant impact on the H2 recovery efficiency where a more homogenous rock would lead to improved H2 productivity. The inclusion of relative permeability hysteresis resulted in a drop in the H2 injectivity and recovery due to H2 discontinuity inside the aquifer which leads to residual H2 during the withdrawal periods. In contrast the effects of hydrogen solubility and hydrogen diffusion were negligible when studied each in isolation from other factors. Hence it is essential to properly account for hysteresis and heterogeneity when evaluating UHS in aquifers.
Cushion Gas in Hydrogen Storage—A Costly CAPEX or a Valuable Resource for Energy Crises?
Dec 2022
Publication
The geological storage of hydrogen is a seasonal energy storage solution and the storage capacity of saline aquifers is most appropriately defined by quantifying the amount of hydrogen that can be injected and reproduced over a relevant time period. Cushion gas stored in the reservoir to support the production of the working gas is a CAPEX which should be reduced to decrease implementation cost for gas storage. The cushion gas to working gas ratio provides a sufficiently accurate reflection of the storage efficiency with higher ratios equating to larger initial investments. This paper investigates how technical measures such as well configurations and adjustments to the operational size and schedule can reduce this ratio and the outcomes can inform optimisation strategies for hydrogen storage operations. Using a simplified open saline aquifer reservoir model hydrogen storage is simulated with a single injection and production well. The results show that the injection process is more sensitive to technical measures than the production process; a shorter perforation and a smaller well diameter increases the required cushion gas for the injection process but has little impact on the production. If the storage operation capacity is expanded and the working gas volume increased the required cushion gas to working gas ratio increases for injection reducing the efficiency of the injection process. When the reservoir pressure has more time to equilibrate less cushion gas is required. It is shown that cushion gas plays an important role in storage operations and that the tested optimisation strategies impart only minor effects on the production process however there is significant need for careful optimisation of the injection process. It is suggested that the recoverable part of the cushion gas could be seen as a strategic gas reserve which can be produced during an energy crisis. In this scenario the recoverable cushion gas could be owned by the state and the upfront costs for gas storage to the operator would be reduced making the implementation of more gas storage and the onset of hydrogen storage more attractive to investors.
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