Transmission, Distribution & Storage
Light-Driven Hydrogen Evolution Assisted by Covalent Organic Frameworks
Jun 2021
Publication
Covalent organic frameworks (COFs) are crystalline porous organic polymers built from covalent organic blocks that can be photochemically active when incorporating organic semiconducting units such as triazine rings or diacetylene bridges. The bandgap charge separation capacity porosity wettability and chemical stability of COFs can be tuned by properly choosing their constitutive building blocks by extension of conjugation by adjustment of the size and crystallinity of the pores and by synthetic post-functionalization. This review focuses on the recent uses of COFs as photoactive platforms for the hydrogen evolution reaction (HER) in which usually metal nanoparticles (NPs) or metallic compounds (generally Pt-based) act as co-catalysts. The most promising COF-based photocatalytic HER systems will be discussed and special emphasis will be placed on rationalizing their structure and light-harvesting properties in relation to their catalytic activity and stability under turnover conditions. Finally the aspects that need to be improved in the coming years will be discussed such as the degree of dispersibility in water the global photocatalytic efficiency and the robustness and stability of the hybrid systems putting emphasis on both the COF and the metal co-catalyst.
Pt Catalytic Effects on the Corrosion and Hydrogen Chemisorption Properties of Zircaloy-2
Dec 2020
Publication
Noble metals are added to boiling water reactors (BWRs) to mitigate stress corrosion cracking of structural components made from steels and Ni-based alloys and this technology is referred to as Noble Metal Chemical Addition (NMCA) or NobleChemTM. There is a growing concern that NMCA can cause unwanted harmful effects on the corrosion and hydrogen uptake properties of Zircaloy-2 fuel cladding. To investigate this we have subjected Zircaloy-2 fuel claddings to out-of-pile BWR conditions in a custom-built autoclave. These claddings are oxidized in pressurized hot water (280 °C 9 MPa) for 25 60 and 150 days wherein Pt nanoparticles (~10 nm) were simultaneously injected. Cross-sectional focused ion beam cuts made at the oxide-metal interface reveal that the oxide growth is not significantly influenced by the local Pt loadings (≤ 1 µg·cm-2). Surprisingly an inverse correlation was observed between oxide thicknesses and metal's hydrogen contents. Interestingly Pt catalysts have led to diminished hydrogen absorption in specimens with liner exposed to the hot water. Overall Pt catalysts exhibited no detrimental effects on the corrosion rate and hydrogen absorption in Zircaloy-2.
Structural Model of Power Grid Stabilization in the Green Hydrogen Supply Chain System—Conceptual Assumptions
Jan 2022
Publication
The paper presents the conceptual assumptions of research concerning the design of a theoretical multi-criteria model of a system architecture to stabilize the operation of power distribution networks based on a hydrogen energy buffer taking into account the utility application of hydrogen. The basis of the research process was a systematic literature review using the technique of in-depth analysis of full-text articles and expert consultations. The structural model concept was described in two dimensions in which the identified variables were embedded. The first dimension includes the supply chain phases: procurement and production with warehousing and distribution. The second dimension takes into account a comprehensive and interdisciplinary approach and includes the following factors: technical economic–logistical locational and formal–legal.
Microfluidics-based Analysis of Dynamic Contact Angles Relevant for Underground Hydrogen Storage
May 2022
Publication
Underground Hydrogen Storage (UHS) is an attractive technology for large-scale (TWh) renewable energy storage. To ensure the safety and efficiency of the UHS it is crucial to quantify the H2 interactions with the reservoir fluids and rocks across scales including the micro scale. This paper reports the experimental measurements of advancing and receding contact angles for different channel widths for a H2 /water system at P = 10 bar and T = 20 ◦C using a microfluidic chip. To analyse the characteristics of the H2 flow in straight pore throats the network is designed such that it holds several straight channels. More specifically the width of the microchannels range between 50 μm and 130 μm. For the drainage experiments H2 is injected into a fully water saturated system while for the imbibition tests water is injected into a fully H2 -saturated system. For both scenarios high-resolution images are captured starting the introduction of the new phase into the system allowing for fully-dynamic transport analyses. For better insights N2 /water and CO2 /water flows were also analysed and compared with H2 /water. Results indicate strong water-wet conditions with H2 /water advancing and receding contact angles of respectively 13◦–39◦ and 6◦–23◦ . It was found that the contact angles decrease with increasing channel widths. The receding contact angle measured in the 50 μm channel agrees well with the results presented in the literature by conducting a core-flood test for a sandstone rock. Furthermore the N2 /water and CO2 /water systems showed similar characteristics as the H2 /water system. In addition to the important characterization of the dynamic wettability the results are also crucially important for accurate construction of pore-scale simulators.
Direct Evidence for Solid-like Hydrogen in a Nanoporous Carbon Hydrogen Storage Material at Supercritical Temperatures
Jul 2015
Publication
Here we report direct physical evidence that confinement of molecular hydrogen (H2) in an optimized nanoporous carbon results in accumulation of hydrogen with characteristics commensurate with solid H2 at temperatures up to 67 K above the liquid vapor critical temperature of bulk H2. This extreme densification is attributed to confinement of H2 molecules in the optimally sized micropores and occurs at pressures as low as 0.02 MPa. The quantities of contained solid-like H2 increased with pressure and were directly evaluated using in situ inelastic neutron scattering and confirmed by analysis of gas sorption isotherms. The demonstration of the existence of solid-like H2 challenges the existing assumption that supercritical hydrogen confined in nanopores has an upper limit of liquid H2 density. Thus this insight offers opportunities for the development of more accurate models for the evaluation and design of nanoporous materials for high capacity adsorptive hydrogen storage.
Hydrogen Storage by Liquid Hydrogen Carriers: Catalyst, Renewable Carrier, and Technology - A Review
Mar 2023
Publication
Hydrogen has attracted widespread attention as a carbon-neutral energy source but developing efficient and safe hydrogen storage technologies remains a huge challenge. Recently liquid organic hydrogen carriers (LOHCs) technology has shown great potential for efficient and stable hydrogen storage and transport. This technology allows for safe and economical large-scale transoceanic transportation and long-cycle hydrogen storage. In particular traditional organic hydrogen storage liquids are derived from nonrenewable fossil fuels through costly refining procedures resulting in unavoidable environmental contamination. Biomass holds great promise for the preparation of LOHCs due to its unique carbon-balance properties and feasibility to manufacture aromatic and nitrogen-doped compounds. According to recent studies almost 100% conversion and 92% yield of benzene could be obtained through advanced biomass conversion technologies showing great potential in preparing biomass-based LOHCs. Overall the present LOHCs systems and their unique applications are introduced in this review and the technical paths are summarized. Furthermore this paper provides an outlook on the future development of LOHCs technology focusing on biomass-derived aromatic and N-doped compounds and their applications in hydrogen storage.
Residual Tensile Properties of Carbon Fiber Reinforced Epoxy Resin Composites at Elevated Temperatures
Sep 2021
Publication
Carbon fiber reinforced epoxy resin composites have attracted great attention in high pressure hydrogen storage for its light weight and excellent mechanical properties. The degradation of residual mechanical properties at elevated temperature from 20 °C to 450 °C were studied experimentally. The effects of temperature on the tensile strength and failure mode of the composite specimens with stacking sequences of 0° 90° and ±45° (labeled as CF0 CF90 and CF 45) were systematically analyzed followed by the fracture surfaces examination. Results show that the tensile strength residual ratios of the three kinds of specimens decrease significantly with heating temperature increasing. In particular the decomposing temperature of the resin matrix exerts the largest effects on the degradation of tensile strength of CF0 specimen within 450 °C. While the loss of tensile strength of CF90 and CF45 specimens is dependent on the thermal softening of epoxy resin which has closely related to the glass transition temperature. Furthermore the debonding and fiber softening appeared in the CF0 specimens when the temperature reached 450 °C. For CF90 specimens the degradation of bonding strength of epoxy could be found at 150 °C and regarding CF45 specimens delamination cracking between plies occurred extensively when the temperature above 125 °C.
Large-scale Long-distance Land-based Hydrogen Transportation Systems: A Comparative Techno-economic and Greenhouse Gas Emission Assessment
Aug 2022
Publication
Interest in hydrogen as an energy carrier is growing as countries look to reduce greenhouse gas (GHG) emissions in hard-to-abate sectors. Previous works have focused on hydrogen production well-to-wheel analysis of fuel cell vehicles and vehicle refuelling costs and emissions. These studies use high-level estimates for the hydrogen transportation systems that lack sufficient granularity for techno-economic and GHG emissions analysis. In this work we assess and compare the unit costs and emission footprints (direct and indirect) of 32 systems for hydrogen transportation. Process-based models were used to examine the transportation of pure hydrogen (hydrogen pipeline and truck transport of gaseous and liquified hydrogen) hydrogen-natural gas blends (pipeline) ammonia (pipeline) and liquid organic hydrogen carriers (pipeline and rail). We used sensitivity and uncertainty analyses to determine the parameters impacting the cost and emission estimates. At 1000 km the pure hydrogen pipelines have a levelized cost of $0.66/kg H2 and a GHG footprint of 595 gCO2eq/kg H2. At 1000 km ammonia liquid organic hydrogen carrier and truck transport scenarios are more than twice as expensive as pure hydrogen pipeline and hythane and more than 1.5 times as expensive at 3000 km. The GHG emission footprints of pure hydrogen pipeline transport and ammonia transport are comparable whereas all other transport systems are more than twice as high. These results may be informative for government agencies developing policies around clean hydrogen internationally.
Research on High-Pressure Hydrogen Pre-Cooling Based on CFD Technology in Fast Filling Process
Dec 2021
Publication
In the fast filling process in order to control the temperature of the vehicle-mounted storage tank not to exceed the upper limit of 85 ◦C it is an effective method to add a hydrogen pre-cooling system upstream of the hydrogenation machine. In this paper Fluent is used to simulate the heat transfer process of high-pressure hydrogen in a shell-and-tube heat exchanger and the phase change process of refrigerant R23. The accuracy of the model is proven by a comparison with the data in the references. Using this model the temperature field and gas volume fraction in the heat transfer process are obtained which is helpful to analyze the heat transfer mechanism. At the same time the influence of hydrogen inlet temperature hydrogen inlet pressure and refrigerant flow rate on the refrigeration performance was studied. The current work shows that the model can be used to determine the best working parameters in the pre-cooling process and reduce the operating cost of the hydrogen refueling station.
Comparative Sustainability Study of Energy Storage Technologies Using Data Envelopment Analysis
Mar 2022
Publication
The transition to energy systems with a high share of renewable energy depends on the availability of technologies that can connect the physical distances or bridge the time differences between the energy supply and demand points. This study focuses on energy storage technologies due to their expected role in liberating the energy sector from fossil fuels and facilitating the penetration of intermittent renewable sources. The performance of 27 energy storage alternatives is compared considering sustainability aspects by means of data envelopment analysis. To this end storage alternatives are first classified into two clusters: fast-response and long-term. The levelized cost of energy energy and water consumption global warming potential and employment are common indicators considered for both clusters while energy density is used only for fast-response technologies where it plays a key role in technology selection. Flywheel reveals the highest efficiency between all the fast-response technologies while green ammonia powered with solar energy ranks first for long-term energy storage. An uncertainty analysis is incorporated to discuss the reliability of the results. Overall results obtained and guidelines provided can be helpful for both decision-making and research and development purposes. For the former we identify the most appealing energy storage options to be promoted while for the latter we report quantitative improvement targets that would make inefficient technologies competitive if attained. This contribution paves the way for more comprehensive studies in the context of energy storage by presenting a powerful framework for comparing options according to multiple sustainability indicators.
A Multi-period Sustainable Hydrogen Supply Chain Model Considering Pipeline Routing and Carbon Emissions: The Case Study of Oman
Nov 2022
Publication
This paper presents a mathematical model for a multi-period hydrogen supply chain design problem considering several design features not addressed in other studies. The model is formulated as a mixed-integer program allowing the production and storage facilities to be extended over time. Pipeline and tube trailer transport modes are considered for carrying hydrogen. The model also allows finding the optimal pipeline routes and the number of transport units. The objective is to obtain an efficient supply chain design within a given time frame in a way that the demand and carbon dioxide emissions constraints are satisfied and the total cost is minimized. A computer program is developed to ease the problem-solving process. The computer program extracts the geographical information from Google Maps and solves the problem using an optimization solver. Finally the applicability of the proposed model is demonstrated in a case study from Oman.
Permeability Modeling and Estimation of Hydrogen Loss through Polymer Sealing Liners in Underground Hydrogen Storage
Apr 2022
Publication
Fluctuations in renewable energy production especially from solar and wind plants can be solved by large‐scale energy storage. One of the possibilities is storing energy in the form of hydrogen or methane–hydrogen blends. A viable alternative for storing hydrogen in salt caverns is Lined Rock Cavern (LRC) underground energy storage. One of the most significant challenges in LRC for hydrogen storage is sealing liners which need to have satisfactory sealing and mechanical properties. An experimental study of hydrogen permeability of different kinds of polymers was conducted followed by modeling of hydrogen permeability of these materials with different additives (graphite halloysite and fly ash). Fillers in polymers can have an impact on the hydrogen permeability ratio and reduce the amount of polymer required to make a sealing liner in the reservoir. Results of this study show that hydrogen permeability coefficients of polymers and estimated hydrogen leakage through these materials are similar to the results of salt rock after the salt creep process. During 60 days of hydrogen storage in a tank of 1000 m2 inner surface 1 cm thick sealing liner and gas pressure of 1.0 MPa only approx. 1 m3STP of hydrogen will diffuse from the reservoir. The study also carries out the modeling of the hydrogen permeability of materials using the Max‐ well model. The difference between experimental and model results is up to 17% compared to the differences exceeding 30% in some other studies.
Underground Bio-methanation: Concept and Potential
Feb 2020
Publication
As a major part of the energy turn around the European Union and other countries are supporting the development of renewable energy technologies to decrease nuclear and fossil energy production. Therefore efficient use of renewable energy resources is one challenge as they are influenced by environmental conditions and hence the intensity of resources such as wind or solar power fluctuates. To secure constant energy supply suitable energy storage and conversion techniques are required. An upcoming solution is the utilization and storage of hydrogen or hydrogen-rich natural gas in porous formations in the underground. In the past microbial methanation was observed as a side effect during these gas storage operations. The concept of underground bio-methanation arised which uses the microbial metabolism to convert hydrogen and carbon dioxide into methane. The concept consists of injecting gaseous hydrogen and carbon dioxide into an underground structure during energy production peaks which are subsequently partly converted into methane. The resulting methane-rich gas mixture is withdrawn during high energy demand. The concept is comparable to engineered bio-reactors which are already locally integrated into the gas infrastructure. In both technologies the conversion process of hydrogen into methane is driven by hydrogenotrophic methanogenic archaea present in the aqueous phase of the natural underground or above-ground engineered reactor. Nevertheless the porous medium in the underground provides compared to the engineered bio-reactors a larger interface between the gas and aqueous phase caused by the enormous volume in the underground porous media. The following article summarizes the potential and concept of underground methanation and the current state of the art in terms of laboratory investigations and pilot tests. A short system potential analysis shows that an underground bio-reactor with a storage capacity of 850 Mio. Sm3 could deliver methane to more than 600000 households based on a hydrogen production from renewable energies.
Evaluation of Conceptual Electrolysis-based Energy Storage Systems Using Gas Expanders
Feb 2020
Publication
In this study four energy storage systems (Power-to-Gas-to-Power) were analysed that allow electrolysis products to be fully utilized immediately after they are produced. For each option the electrolysis process was supplied with electricity from a wind farm during the off-peak demand periods. In the first two variants the produced hydrogen was directed to a natural gas pipeline while the third and fourth options assumed the use of hydrogen for synthetic natural gas production. All four variants assumed the use of a gas expander powered by high-temperature exhaust gases generated during gas combustion. In the first two options gas was supplied from a natural gas network while synthetic natural gas produced during methanation was used in the other two options. A characteristic feature of all systems was the combustion of gaseous fuels within a ballast-free oxidant atmosphere without nitrogen which is the fundamental component of air in conventional systems. The fifth variant was a reference for the systems equipped with gas expanders and assumed the use of fuel cells for power generation. To evaluate the individual variants the energy storage efficiency was defined and determined and the calculated overall efficiency ranged from 17.08 to 23.79% which may be comparable to fuel cells.
NewGasMet - Flow Metering of Renewable Gases (Biogas, Biomethane, Hydrogen, Syngas and Mixtures with Natural Gas): Effect of the Renewable Gases on the Uncertainty Budgets of Gas Meters
Sep 2022
Publication
During the study of the CEN/TC 237 standards “Gas meters” in the European Metrology Programme for Innovation and Research (EMPIR) project named NEWGASMET the impact of the renewable gases (biogas biomethane hydrogen syngas and mixtures with natural gas) on the uncertainty on the gas meter was discussed and described in several recommendation reports. This report is on the activity A2.1.15 where the objective is “Using input from A2.1.2-A2.1.8 FORCE with support from Cesame CMI NEL PTB VSL and ISSI will write a report on the effects of renewable gases on the uncertainty budgets of gas meters.”
Assessment of Operability and Inspection, Maintenance and Repair Requirements for Transmission Pipelines and Installations in Hydrogen Service
Apr 2021
Publication
This report has been prepared for Hytechnical work programme to support the technical strategy for repurposing existing transmission pipelines and installations for the transportation and distribution of hydrogen and natural gas / hydrogen blends. The aim of the Hytechnical work programme is to support the implementation of the IGEM supplements to the standards TD/1 TD/13 TD/3 and TD/4.<br/>The report covers a desk study into the requirements for the inspection maintenance operation and repair of above 7 bar natural gas pipelines and installations designed and operated in accordance with the standards existing IGEM/TD/1 and IGEM/TD/13 which are repurposed for hydrogen service.
A Comprehensive Evaluation of a Novel Integrated System Consisting of Hydrogen Boil-off Gas Reliquifying Process and Polymer Exchange Membrane Fuel Cell Using Exergoeconomic and Markov Analyses
Dec 2021
Publication
The price of constructing hydrogen generation units is very high and sometimes it is not possible to build them in the desired location so the transfer of hydrogen from the hydrogen generation system to the units that need it is justified. Since the storage of hydrogen gas needs a large volume and its transportation is very complex so if hydrogen is stored in liquid form this problem can be resolved. In transporting liquid hydrogen (LH2) over long distances owing to heat transfer to the environment the LH2 vaporizes forming boil-off gas (BOG). Herein in lieu of only reliquifying the BOG this study proposes and assesses a system employing the BOG partially as feed for a novel liquefaction process and also the remaining utilized in a proton exchange membrane fuel cell (PEMFC) to generate power. Using the cold energy of the onsite liquid oxygen utility of the LH2 cargo vessel the mixed refrigerant liquefaction cycle is further cooled down. In this regard by using 130 kg/h BOG as input 60.37 kg/h of liquid hydrogen is produced and the rest enters PEMFC with 552.7 kg/h oxygen to produce 1592 kW of power. The total thermal efficiency of the integrated system and electrical efficiency of the PEMFC is 83.18% and 68.76% respectively. Regarding the liquefaction cycle its specific power consumption (SPC) and coefficient of performance (COP) were achieved at 3.203 kWh/kgLH2 and 0.1876 respectively. The results of exergy analysis show that the exergy destruction of the whole system is 937.4 kW and also its exergy efficiency is calculated to be 58.38%. Exergoeconomic and Markov analyses have also been applied to the integrated system. Also by changing the important parameters of PEMFC its optimal performance has been extracted.
Impact of Polymers on Magnesium-Based Hydrogen Storage Systems
Jun 2022
Publication
In the present scenario much importance has been provided to hydrogen energy systems (HES) in the energy sector because of their clean and green behavior during utilization. The developments of novel techniques and materials have focused on overcoming the practical difficulties in the HES (production storage and utilization). Comparatively considerable attention needs to be provided in the hydrogen storage systems (HSS) because of physical-based storage (compressed gas cold/cryo compressed and liquid) issues such as low gravimetric/volumetric density storage conditions/parameters and safety. In material-based HSS a high amount of hydrogen can be effectively stored in materials via physical or chemical bonds. In different hydride materials Mg-based hydrides (Mg–H) showed considerable benefits such as low density hydrogen uptake and reversibility. However the inferior sorption kinetics and severe oxidation/contamination at exposure to air limit its benefits. There are numerous kinds of efforts like the inclusion of catalysts that have been made for Mg–H to alter the thermodynamic-related issues. Still those efforts do not overcome the oxidation/contamination-related issues. The developments of Mg–H encapsulated by gas-selective polymers can effectively and positively influence hydrogen sorption kinetics and prevent the Mg–H from contaminating (air and moisture). In this review the impact of different polymers (carboxymethyl cellulose polystyrene polyimide polypyrrole polyvinylpyrrolidone polyvinylidene fluoride polymethylpentene and poly(methyl methacrylate)) with Mg–H systems has been systematically reviewed. In polymer-encapsulated Mg–H the polymers act as a barrier for the reaction between Mg–H and O2/H2O selectively allowing the H2 gas and preventing the aggregation of hydride nanoparticles. Thus the H2 uptake amount and sorption kinetics improved considerably in Mg–H.
Pore-scale Study of Microbial Hydrogen Consumption and Wettability Alteration During Underground Hydrogen Storage
Feb 2023
Publication
Hydrogen can be a renewable energy carrier and is suggested to store renewable energy and mitigate carbon dioxide emissions. Subsurface storage of hydrogen in salt caverns deep saline formations and depleted oil/gas reservoirs would help to overcome imbalances between supply and demand of renewable energy. Hydrogen however is one of the most important electron donors for many subsurface microbial processes including methanogenesis sulfate reduction and acetogenesis. These processes cause hydrogen loss and changes of reservoir properties during geological hydrogen storage operations. Here we report the results of a typical halophilic sulfate-reducing bacterium growing in a microfluidic pore network saturated with hydrogen gas at 35 bar and 37°C. Test duration is 9 days. We observed a significant loss of H2 from microbial consumption after 2 days following injection into a microfluidic device. The consumption rate decreased over time as the microbial activity declined in the pore network. The consumption rate is influenced profoundly by the surface area of H2 bubbles and microbial activity. Microbial growth in the silicon pore network was observed to change the surface wettability from a water-wet to a neutral-wet state. Due to the coupling effect of H2 consumption by microbes and wettability alteration the number of disconnected H2 bubbles in the pore network increased sharply over time. These results may have significant implications for hydrogen recovery and gas injectivity. First pore-scale experimental results reveal the impacts of subsurface microbial growth on H2 in storage which are useful to estimate rapidly the risk of microbial growth during subsurface H2 storage. Second microvisual experiments provide critical observations of bubble-liquid interfacial area and reaction rate that are essential to the modeling that is needed to make long-term predictions. Third results help us to improve the selection criteria for future storage sites.
The Role of Hydrogen in the Corrosion and Cracking of Steels - A Review
Oct 2021
Publication
In many processes of steel industrial including steel manufacture storage and service hydrogen could be absorbed into metallic materials and the absorbed hydrogen seriously impaired its corrosion resistance. This paper provides a comprehensive review on the effects of hydrogen on passive film anodic dissolution pitting corrosion and stress corrosion cracking and based on the review the mechanism by which hydrogen promotes corrosion of steel and subsequently leads to cracking has been discussed. It is envisaged that hydrogen harms the stability of the passive film and as a result escalates anode’s activation of steel eventually leading to pitting and stress corrosion cracking.
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