Transmission, Distribution & Storage

This study presents the synthesis and evaluation of activated carbon derived from spent coffee grounds using three distinct activation methods namely chemical ultrasound-assisted and surface magnetized. The characterization studies of materials are used to evaluate hydrogen storage performance under varying pressure and temperature conditions. The gravimetric measurements are employed to assess the physisorption capacities while electrochemical techniques such as LSV CV and GCD evaluate hydrogen related charge storage behavior. The activation methods affect surface morphology and elemental composition of the activated carbon samples as confirmed by SEM and EDS analyses. Among the three chemically activated carbon exhibits the highest hydrogen uptake achieving 0.362 wt% at 0 ◦C and 4 kPa which is attributed to its highly porous structure. The ultrasound-assisted and surface magnetized samples exhibitmaximum capacities of 0.357 wt% and 0.339 wt% respectively. This study underlines the potential of coffee waste as a sustainable carbon precursor and introduces a dual-characterization approach.

Efficient hydrogen storage is critical for advancing hydrogen-based technologies. This study investigates the effects of pressure and surface area on hydrogen storage in three carbon-based materials: graphite graphene oxide and reduced graphene oxide. Hydrogen adsorption–desorption experiments under pressures ranging from 1 to 9 bar revealed nonlinear storage capacity responses with optimal performance at around 5 bar. The specific surface area plays a pivotal role with reduced graphene oxide and exhibiting a surface area of 70.31 m2/g outperforming graphene oxide (33.75 m2/g) and graphite (7.27 m2/g). Reduced graphene oxide achieved the highest hydrogen storage capacity with 768 sccm and a 3 wt.% increase over the other materials. In assessing proton-exchange fuel cell performance this study found that increased hydrogen storage correlates with enhanced power density with reduced graphene oxide reaching a maximum of 0.082 W/cm2 compared to 0.071 W/cm2 for graphite and 0.017 W/cm2 for graphene oxide. However desorption rates impose temporal constraints on fuel cell operation. These findings enhance our understanding of pressure–surface interactions and underscore the balance between hydrogen storage capacity surface area and practical performance in carbon-based materials offering valuable insights for hydrogen storage and fuel cell applications.

Hydrogen emissions arise from leakage during its production transport storage and use leading to an increase in atmospheric hydrogen concentrations. These emissions also cause an indirect climate effect which has been quantified in the literature with a global warming potential over 100 years (GWP100) of about 11.6 placing hydrogen between carbon dioxide (1) and methane (29.8). There is increasing debate about the climate impact of an energy transition based on hydrogen. As a case study we have therefore evaluated the expected climate impact of switching from the long-distance natural gas transmission network to the outlined future “hydrogen core network” in Germany. Our analysis focuses on the relevant sources and network components of emissions. Our results show that the emissions from the network itself represent only about 1.8% of total emissions from the transmission of hydrogen with 98% attributed to energy-related compressor emissions and only 2% to fugitive and operational hydrogen leakage. Compared to the current natural gas transmission network we calculate a 99% reduction in total network emissions and a 97% reduction in specific emissions per transported unit of energy. In the discussion we show that when considering the entire life cycle which also includes emissions from the upstream and end-use phases the switch to hydrogen reduces the overall climate impact by almost 90%. However while our results show a significantly lower climate impact of hydrogen compared to natural gas minimising any remaining emissions remains crucial to achieve carbon neutrality by 2045 as set in Germany’s Federal Climate Action Act. Hence we recommend further reducing the emissions intensity of hydrogen supply and minimising the indirect emissions associated with the energy supply of compressors.

As the need for sustainable hydrogen storage solutions increases enhancing the bonding interface between polymer liners and carbon fiber-reinforced polymer (CFRP) in Type IV hydrogen tanks is essential to ensure tank integrity and safety. This study investigates the effect of plasma treatment on polyethylene (PE) and PE/graphene nanoplatelets (GNP) composites to optimize bonding with CFRP simulating the liner-CFRP interface in hydrogen tanks. Initially plasma treatment effects on PE surfaces were assessed focusing on plasma energy and exposure time with key surface modifications characterized and bonding performance being evaluated. Plasma treatment on PE/GNP composites with increasing GNP content was then examined comparing the bonding effectiveness of untreated and plasma-treated samples. Wedge peel tests revealed that plasma treatment significantly enhanced PE-CFRP bonding with optimal conditions at 510 W and 180 s resulting in 212 % and 165 % increases in the wedge peel strength and fracture energy respectively. Plasma-treated PE/GNP composites with 0.75 wt.% GNP achieved a notable bonding enhancement with CFRP showing 528 % and 269 % improvements in strength and fracture energy over untreated neat PE-CFRP samples. These findings offer practical implications for improving the mechanical performance of hydrogen storage tanks contributing to safer and more efficient hydrogen storage systems for a sustainable energy future.

Zero-export photovoltaic systems are an option to transition to Smart Grids. They decarbonize the sector without affecting third parties. This paper proposes the analysis of a zero-export PVS with a green hydrogen generation and storage system. This configuration is feasible to apply by any selfgeneration entity; it allows the user to increase their resilience and independence from the electrical network. The technical issue is simplified because the grid supplies no power. The main challenge is finding an economic balance between the savings in electricity billing proportional to the local electricity rate and the complete system’s investment operation and maintenance expenses. This manuscript presents the effects of the power sizing on the efficacy of economic savings in billing (ηSaving ) and the effects of the cost reduction on the levelized cost of energy (LCOE) and a discounted payback period (DPP) based on net present value. In addition this study established an analytical relationship between LCOE and DPP. The designed methodology pro poses to size and selects systems to use and store green hydrogen from the zero-export photo voltaic system. The input data in the case study are obtained experimentally from the Autonomous University of the State of Quintana Roo located on Mexico’s southern border. The maximum power of the load is LPmax = 500 kW and the average power is LPmean = 250 kW; the tariff of the electricity network operator has hourly conditions for a medium voltage demand. A suggested semi-empirical equation allows for determining the efficiency of the fuel cell and electrolyzer as a function of the local operating conditions and the nominal power of the com ponents. The analytical strategy the energy balance equations and the identity functions that delimit the operating conditions are detailed to be generalized to other case studies. The results are obtained by a computer code programmed in C++ language. According to our boundary conditions results show no significant savings generated by the installation of the hydrogen system when the zero-export photovoltaic system Power ≤ LPmax and DPP ≤ 20 years is possible only with LCOE ≤ 0.1 $/kWh. Specifically for the Mexico University case study zero-export photovoltaic system cost must be less than 310 $/kW fuel cell cost less than 395 $/kW and electrolyzer cost less than 460 $/kW.

A composite hydrogen storage vessel (CHSV) is one key component of the hydrogen fuel cell vehicle which always suffers random vibration during transportation resulting in fatigue failure and a reduction in service life. In this paper firstly the free and constrained modes of CHSV are experimentally studied and numerically simulated. Subsequently the random vibration simulation of CHSV is carried out to predict the stress distribution while Steinberg’s method and Dirlik’s method are used to predict the fatigue life of CHSV based on the results of stress distribution. In the end the optimization of ply parameters of the composite winding layer was conducted to improve the stress distribution and fatigue life of CHSV. The results show that the vibration pattern and frequency of the free and constrained modes of CHSV obtained from the experiment tests and the numerical predictions show a good agreement. The maximum difference in the value of the vibration frequency of the free and constrained modes of CHSV from the FEA and experiment tests are respectively 8.9% and 8.0% verifying the accuracy of the finite element model of CHSV. There is no obvious difference between the fatigue life of the winding layer and the inner liner calculated by Steinberg’s method and Dirlik’s method indicating the accuracy of FEA of fatigue life in the software Fe-safe. Without the optimization the maximum stresses of the winding layer and the inner liner are found to be near the head section by 469.4 MPa and 173.0 MPa respectively and the numbers of life cycles of the winding layer and the inner liner obtained based on the Dirlik’s method are around 1.66 × 106 and 3.06 × 106 respectively. Through the optimization of ply parameters of the composite winding layer the maximum stresses of the winding layer and the inner liner are reduced by 66% and 85% respectively while the numbers of life cycles of the winding layer and the inner liner both are increased to 1 × 107 (high cycle fatigue life standard). The results of the study provide theoretical guidance for the design and optimization of CHSV under random vibration.

This article provides an overview of the requirements for a grid-oriented integration of hydrogen energy storage (HES) and components into the power grid. Considering the general definition of HES and the possible components this paper presents future hydrogen demand electrolysis performance and storage capacity. These parameters were determined through various overall system studies aiming for climate neutrality by the year 2045. In Germany the targeted expansion of renewable energy generation capacity necessitates grid expansion to transport electricity from north to south and due to existing grid congestions. Therefore electrolysis systems could be used to improve the integration of renewable energy systems by reducing energy curtailment and providing grid services when needed. Currently however there are hardly any incentives for a grid-friendly allocation and operation of electrolysis or power-to-gas plants. Two possible locations for hydrogen plants from two current research projects HyCavMobil (Hydrogen Cavern for Mobility) and H2-ReNoWe (Hydrogen Region of north-western Lower Saxony) are presented as practical examples. Using power grid models the integration of electrolysis systems at these locations in the current high and extra-high voltage grid is examined. The presented results of load flow calculations assess power line utilization and sensitivity for different case scenarios. Firstly the results show that power lines in these locations will not be overloaded which would mean an uncritical operation of the power grid. While the overall grid stability remains unaffected in this case selecting suitable locations is vital to prevent negative effects on the local grid.

This article presents an innovative approach to address the optimization and planning of hydrogen network transmission focusing on minimizing computational and operational costs including capital operational and maintenance expenses. The mathematical models developed for gas flow rate pipelines junctions and storage form the basis for the optimization problem which aims to reduce costs while satisfying equality inequality and binary constraints. To achieve this we implement a dynamic algorithm incorporating 100 scenarios to account for uncertainty. Unlike conventional successive linear programming methods our approach solves successive piecewise problems and allows comparisons with other techniques including stochastic and deterministic methods. Our method significantly reduces computational time (56 iterations) compared to deterministic (92 iterations) and stochastic (77 iterations) methods. The non-convex nature of the model necessitates careful selection of starting points to avoid local optimal solutions which is addressed by transforming the primal problem into a linear program by fixing the integer variable. The LP problem is then efficiently solved using the Complex Linear Programming Expert (CPLEX) solver enhanced by Monte Carlo simulations for 100 scenarios achieving a 39.13% reduction in computational time. In addition to computational efficiency this approach leads to operational cost savings of 25.02% by optimizing the selection of compressors (42.8571% decreased) and storage facilities. The model’s practicality is validated through realworld simulations on the Belgian gas network demonstrating its potential in solving large-scale hydrogen network transmission planning and optimization challenges.

This work consists of a systematic review showing recent progress and trends in the development of high entropy alloys (HEA) for solid-state hydrogen storage. The information was compiled from academic papers from the following databases: Google Scholar ScienceDirect Springer SCOPUS American Chemical Society MDPI; as well as the patent banks United States Patent and Trademark Office Google Patent and lens.org. This article discusses key aspects such as HEA design (elements used thermodynamic and geometric characteristics thermodynamic simulations and synthesis methods); HEA evaluation focusing on crystallinity thermal behavior and hydrogen storage; HEA-related trends including MgH2 modification the advancement of lightweight alloys and the use of machine learning.

The reliance on hydrogen as part of the transition towards a low-carbon economy will require developing dedicated pipeline infrastructure. This deployment will be shaped by regulatory frameworks governing investment and access conditions ultimately structuring how the commodity is traded. The paper assesses the market design for hydrogen infrastructure assuming the application of unbundling requirements. For this purpose it develops a general economic framework for regulating pipeline infrastructure focusing on asset specificity market power and access rules. The paper assesses the scope of application of infrastructure regulation which can be set to individual pipelines or to entire networks. When treated as entire networks the infrastructure can provide flexibility to enhance market liquidity. However this requires establishing network monopolies which rely on central planning and reduce the overall dynamic efficiency of the sector. The paper further compares the regulation applied to US and EU natural gas pipeline infrastructure. Based on the different challenges faced by the EU hydrogen sector including absence of wholesale concentration and large infrastructure needs the paper draws lessons for a regulatory framework establishing the main building blocks of a hydrogen target model. The paper recommends a review of the current EU regulatory framework in the Hydrogen and Decarbonised Gas Package to enable i) the application of regulation to individual pipelines rather than entire networks; ii) the use of negotiated third-party access light-touch regulation and possibly marketbased coordination mechanisms for the access to the infrastructure and iii) a more significant role for long-term capacity contracts to underpin infrastructure investments.