Hydrogen Station Research Articles

Mitigating risks in hydrogen-powered transportation: A comprehensive risk assessment for hydrogen refuelling stations, vehicles, and garages

Hydrogen is increasingly seen as a viable alternative to fossil fuels in transportation, crucial to achieving net-zero energy goals. However, the rapid expansion of hydrogen-powered transportation is outpacing safety standards, posing significant risks due to limited operational experience, involvement of new actors and lack of targeted guidelines. This study addresses the urgent need for a tailored comprehensive risk assessment framework. Using Structured What-If (SWIFT) and bowtie barrier analysis, the research evaluates a hypothetical pilot project focusing on hydrogen refuelling stations, vehicles, and garages. The study identifies critical hazards and assesses the adequacy of current risk mitigation measures. Key findings reveal gaps in safety practices, leading to 41 actionable steps and 5 key activities to help new actors manage hydrogen risks effectively. By introducing novel safety guidelines, this research contributes to the development of safe hydrogen use and advances the understanding of hydrogen risks, ensuring its sustainable integration into transportation systems.

Optimizing Hydrogen Refueling Station Recommendations: A Comparative Analysis Between Genetic Algorithm and Particle Swarm Optimization

Optimizing Hydrogen Refueling Station Recommendations: A Comparative Analysis Between Genetic Algorithm and Particle Swarm Optimization

First detection of industrial hydrogen emissions using high precision mobile measurements in ambient air

Projections towards 2050 of the global hydrogen (H2) demand indicate an eight-fold increase in present-day hydrogen consumption. Leakage during production, transport, and consumption therefore presents a large potential for increases in the atmospheric hydrogen burden. Although not a greenhouse gas itself, hydrogen has important indirect climate effects, and the Global Warming Potential of H2 is estimated to be 12.8 times that of CO2. Available technologies to detect hydrogen emissions have been targeted at risk mitigation of industrial facilities, while smaller climate-relevant emissions remain undetected. The latter requires measurement capacity at the parts-per-billion level (ppb). We developed and demonstrated an effective method to detect small hydrogen emissions from industrial installations that combines active AirCore sampling with ppb-precision analysis by gas chromatography. We applied our methodology at a chemical park in the province of Groningen, the Netherlands, where several hydrogen production and storage facilities are concentrated. From a car and an unmanned aerial vehicle, we detected and quantified for the first time small but persistent industrial emissions from leakage and purging across the hydrogen value chain, which include electrolysers, a hydrogen fuelling station, and chemical production plants. Our emission estimates indicate current loss rates up to 4.2% of the estimated production and storage in these facilities. This is sufficiently large to urgently flag the need for monitoring and verification of H2 emissions for the purpose of understanding our climate change trajectory in the 21st century.

CFD Analysis of the Effects of a Barrier in a Hydrogen Refueling Station Mock-Up Facility during a Vapor Cloud Explosion Using the radXiFoam v2.0 Code

A CFD (computational fluid dynamics) analysis to investigate the effects of the installation of a barrier in a hydrogen refueling station (HRS) mock-up facility, with a dummy vehicle and dispensers in the vapor cloud region, during a hydrogen-air explosion using a gas mixture volume of 70.16 m3 was conducted to determine whether the radXiFoam v2.0 code with the established analysis methodology to predict the peak overpressure can be utilized to evaluate the safety of a HRS with such a barrier installed in a large city in the Republic of Korea. The radXiFoam v2.0 code was developed on the basis of the XiFoam solver in the open-source CFD software OpenFOAM-v2112 by modifying C++ source codes in several libraries and governing equations so as to ensure effective calculations of the hydrogen-air chemical reaction and radiative heat transfer through water vapor in a humid air environment and to remove unnecessary warning messages that arise when using the radXiFoam v1.0 code. First, we conducted a validation analysis on the basis of measured overpressure datasets from a near field to a far field of a vapor cloud explosion (VCE) site in the HRS mock-up facility to evaluate the uncertainty in prediction datasets by radXiFoam v2.0. After this validation analysis, we undertook CFD sensitivity calculations by installing barriers with heights of 2.1 m and 4.2 m at a horizontal distance of 2.3 m from the VCE region in the grid model used for the validation analysis to assess the effects of these barriers on reducing the peak overpressure of the blast wave. From these calculations, we judged that the radXiFoam v2.0 code can accurately simulate the effects of the barrier during a VCE, as the calculated overpressure reduction values according to the barrier height are reasonable on the basis of previous validation results from Stanford Research Institute’s explosion test with such a barrier. The results herein imply that the radXiFoam v2.0 code is feasible for use in HRS safety when barrier installation must meet the technical regulations of the Korea Gas Safety Corporation in a large city.

A systematic framework of resilience assessment based on multi-state transition modeling under two-phase recovery for hydrogen refueling stations

The safety of Hydrogen refueling station systems is becoming increasingly important with the growth of hydrogen energy. Existing assessment methods for hydrogen refueling stations primarily focus on reliability. They often neglect the recovery process after experiencing shocks. This paper establishes a comprehensive resilience assessment framework for Hydrogen refueling station. It considers a two-state recovery phase with a multi-state transition model. The entire system evolution process is divided into degradation and recovery phases. The transfer rate during the degradation phase is obtained using event and fault tree analysis. The recovery phase is further divided into emergency recovery and post-recovery, generating recovery rate for the entire process. Furthermore, four associated indices for resilience assessment are established: resistance, absorption, recovery, and robustness. A case study based on a typical Hydrogen refueling station system is implemented. The results show that the resilience of the Hydrogen refueling station can be improved by 12.5% with the support of the two-phase recovery process compared to the traditional recovery process. This demonstrates the framework's potential to enhance the reliable operation of Hydrogen refueling station in practice.

A two-layer economic resilience model for distribution network restoration after natural disasters

Improving the resilience of energy networks and minimizing outages is crucial, making the development of self-healing strategies essential for ensuring a continuous power supply and boosting resilience. As decentralized prosumers become more integrated into smart grids, innovative coordination methods are required to fully leverage their potential and improve the system's self-healing capabilities. Hence, in this paper, we present a decentralized two-layer model for active distribution networks (ADNs) incorporating commercial energy hubs, Parking lots (PLs), hydrogen refueling stations, and mobile units (MUs). This model aims to maximize the flexible capacities of flexible prosumers under emergencies and includes a dynamic mechanism for transporting hydrogen to refueling stations via trucks. In the first layer of the model, the AND operator provides the required services to flexible prosumers, including commercial energy hubs, PLs and hydrogen refueling stations. During this layer, the movement paths of mobile units, such as battery-based mobile storage units (MSUs) and mobile hydrogen units (MHUs), are determined. In the second layer, prosumers independently plan and decide the extent of their service contributions. Subsequently, with the actual service capacities established, the AND operator re-optimizes the initial planning to finalize the system schedule and precise movement paths of the mobile units. The proposed model was tested on a modified 83-bus distribution network using the CPLEX solver in GAMS. Simulation results demonstrate a 54.9 % reduction in forced load shedding (FLS) due to the dispatch of mobile units and a further 84.4 %% reduction in FLS from leveraging the flexible capacities of commercial energy hubs and PLs.

Can subsidy policies achieve fuel cell logistics vehicle (FCLV) promotion targets? Evidence from the beijing-tianjin-hebei fuel cell vehicle demonstration city cluster in China

Fuel cell logistics vehicle (FCLV) plays a pillar role in achieving carbon neutrality in the freight sector. Due to high costs and imperfect infrastructure, millions of subsidies are granted to develop FCLV and fulfill promotion targets set by the government. To examine the effectiveness of this action, the study proposes a tripartite evolutionary game theory (EGT) model to simulate the interactions between local governments, private investors, and consumers, and explores the fulfillment of promotion targets in the Beijing-Tianjin-Hebei fuel cell vehicle demonstration city cluster. The obtained results show that: (i) the FCLV promotion targets of demonstration cities except Tangshan could be substantially achieved under the current subsidy; (ii) purchase subsidies for consumers can help achieve promotion targets at a faster pace, while construction subsidies for investors have a limited incentive effect, so more non-financial incentives need to be provided to investors, such as innovative operating models and priority approval of land for hydrogen refueling station construction; (iii) a comparison of subsidies in different cities reveals that Beijing's subsidies are the most efficient and that there is an optimal allocation between consumers and private investors that allows for the faster accomplishment of promotion targets without increasing the fiscal burden.

A novel two-stage optimal layout model of hydrogen refueling facility network based on green electricity hydrogen production: Beijing-Tianjin-Hebei region of China as case study

Green electricity hydrogen production(GEHP) is fundamental support for developing new-type power system and achieving the green and low-carbon transformation in the transportation sector. It is key issue to build a hydrogen refueling facility network(HRFN) to link hydrogen production and consumption. Firstly, the framework of HRFN is proposed including hydrogen production points(HPP), hydrogen refueling stations(HRS) and hydrogen demand points(HDP). Secondly, a two-stage model is built. In the first stage, the siting model of HRS cluster is constructed considering the service capacity, service radius, and construction, operation and penalty costs. In the second stage, the bi-objective planning model of HRFN is constructed considering network stability, hydrogen storage and transportation forms and producing total costs. Finally, the Beijing-Tianjin-Hebei region of China(BTH) is taken as case study to verify the effectiveness. Sensitivity analyses are conducted on four factors:HRSs’ service radius, service capacity, GEHP’s efficiency and HDPs’ scope. The key findings are: 1)the service radius and capacity of HRSs and HDPs’ scope all affect the layout of HRSs, with HDPs’ scope further influencing HPPs’ number; 2)the construction and operation costs are more impacted by changes in GEHP's efficiency compared to network stability;3)the network should be strengthened to cover the whole processes from hydrogen production to consumption.

Common but differentiated? Policymakers’ priorities of social acceptance for expanding hydrogen refueling stations in Japan and Korea

Improving social acceptance of hydrogen refueling stations (HRSs) involves prioritizing several key factors. Specifically, developing a robust infrastructure of HRSs is critical for implementing hydrogen fuel cell electric vehicles (FCEVs). However, the expansion of HRSs is primarily restricted by the social acceptance of hydrogen-based technologies. Therefore, here, we assessed the perceptions of policymakers regarding the social acceptance of HRSs in Japan and South Korea, where policymakers recognize the vitality of acceptance among residents for advancing FCEV adoption and the importance of market acceptance and sociopolitical acceptance. Japanese experts contend that corporate-level financial feasibility is crucial for achieving social acceptance, whereas South Korean experts prioritize benefit sharing for gaining individual-level acceptance. These insights highlight both common and differentiated factors related to the social acceptance of FCEVs, thereby informing policies on alternative fuel sources to facilitate the broader adoption of HRSs not only in Japan and Korea but also worldwide.

Whole system impacts of decarbonising transport with hydrogen: A Swedish case study

This study aims to carry out a techno-economic analysis of different hydrogen supply chain designs coupled with the Swedish electricity system to study the inter-dependencies between them. Both the hydrogen supply chain designs and the electricity system were parameterized with data for 2030. The supply chain designs comprehend centralised production, decentralised production, a combination of both, and with/without seasonal variation in hydrogen demand. The supply chain design is modelled to minimize the overall cost while meeting the hydrogen demands. The outputs of the supply chain model include the hydrogen refuelling stations' locations, the electrolyser's locations and their respective sizes as well as the operational schedule. The electricity system model shows that the average electricity prices in Sweden for zones SE1, SE2, SE3 and SE4 will be 4.28, 1.88, 8.21, and 8.19 €/MWh respectively. The electricity is mainly generated from wind and hydropower (around 42% each), followed by nuclear (14%), solar (2%) and then bio-energy (0.3%). In addition, the hydrogen supply chain design that leads to a lower overall cost is the decentralised design, with a cost of 1.48 and 1.68 €/kgH2 in scenarios without and with seasonal variation respectively. The seasonal variation in hydrogen demand increases the cost of hydrogen, regardless of the supply chain design.

Hydrogen Refueling Stations: A Review of the Technology Involved from Key Energy Consumption Processes to Related Energy Management Strategies

Over the last few years, hydrogen has emerged as a promising solution for problems related to energy sources and pollution concerns. The integration of hydrogen in the transport sector is one of the possible various applications and involves the implementation of hydrogen refueling stations (HRSs). A key obstacle for HRS deployment, in addition to the need for well-developed technologies, is the economic factor since these infrastructures require high capital investments costs and are largely dependent on annual operating costs. In this study, we review hydrogen’s application as a fuel, summarizing the principal systems involved in HRS, from production to the final refueling stage. In addition, we also analyze the main equipment involved in the production, compression and storage processes of hydrogen. The current work also highlights the main refueling processes that impact energy consumption and the methodologies presented in the literature for energy management strategies in HRSs. With the aim of reducing energy costs due to processes that require high energy consumption, most energy management strategies are based on the use of renewable energy sources, in addition to the use of the power grid.

Developing an internet of things system for hydrogen leak detection at hydrogen refueling stations integrating LoRa and global positioning system

Developing a hydrogen leak detection system that can quickly detect even the smallest amount of hydrogen is extremely crucial in the hydrogen industry. Currently, hydrogen refueling stations use a fixed hydrogen leak detection system. This study develops a mobile hydrogen gas leak detection system for hydrogen refueling stations using s, global positioning system, and Internet of Things (IoT) equipment, including LoRa and Wi-Fi. A digital twin is implemented by linking hydrogen gas-sensing data at a location that is quickly required or suspected using Google Maps. A time-series database is used to store the hydrogen gas-sensing data, and the transfer delay of hydrogen gas-sensing data between the hydrogen equipment was measured. Therefore, we developed a prototype system that transmits, stores, and analyzes hydrogen gas-sensing data in real time using IoT equipment for hydrogen refueling stations.

Model-based fault detection algorithm for liquid hydrogen refueling system using CUSUM method

The global focus on the role of hydrogen energy in achieving carbon neutrality is increasing, particularly in transportation. Establishing and operating hydrogen refueling stations for fuel cell electric vehicles (FCEVs) are gaining prominence. This study proposes a model-based fault detection algorithm to enhance safety at large-capacity liquid hydrogen (LH2) refueling stations. First, the LH2 refueling system is modeled using Aspen HYSYS, estimating the heat transfer coefficient of the storage tank to meet the normal evaporation rate (NER) specification of 0.9 % per day. Second, diverse fault scenarios are identified via a Hazard and Operability Study (HAZOP), and simulation data are generated for the normal and fault scenarios. Finally, a fault detection algorithm utilizing the cumulative summation (CUSUM) is developed, with its threshold determined by risk levels analyzed in HAZOP. This allowed for tighter fault detection as risk levels increased. The algorithm successfully identified faults for all 11 scenarios.

Hydrogen storage and refueling options: A performance evaluation

This study focuses on the comparative modeling and refueling simulations of hydrogen refueling stations for hydrogen-powered vehicles and high-pressure hydrogen storage options in tanks. The study further aims to simulate these under actual conditions in Ontario, Canada for better assessment which can be treated as a case study as well. The specific tests explore the modeling of hydrogen flow between the recharging station to the car's tank, as well as the optimization of transient variations in temperature, pressure and mass flow rate of hydrogen throughout the process of refueling a fuel cell electric vehicle. The H2FILLS program is utilized to assist for the simulation studies. The primary objective is to replicate various practical weather conditions, tank pressures, flow rates, and refueling periods for different categories of high-pressure hydrogen storage tanks and analyze their storage efficiency. The three different commercially available high-pressure type-IV hydrogen storage tanks were considered in the study as tank-I, tank-II and tank-III with working pressures of 500 bar, 700 bar, 700 bar, and hydrogen storage capacity of 9.5 kg, 4.6 kg, and 5 kg, respectively. Seven different ambient temperatures were selected to mimic seasonal effects. When the power output is constant, with temperature increases, flow rate decreases, and therefore time required to refuel also increases. There is a linear relationship between the final mass flow rate and the ambient temperature, where the mass flow rate drops by approximately 1.8 kg/h for every 10 °C rise in temperature. The variation in ultimate mass flow rate between the highest and lowest ambient temperatures is roughly 5.4 kg/h. Based on the refueling time and docking, undocking, downtime it’s been found that approximately five minutes is wasted between each vehicle. This can help reduce average of 230.02 kt, 231.70 kt, and 235.06 kt CO2 emission per year for vehicle-III, vehicle-II, and vehicle-I, respectively. Lastly, yearly CO2 reduction forecast shows that it may reach 0.9 Mt, 1.6 Mt, 2.7Mt, 3.76 Mt, and 4.73 Mt in the year 2030, 2035, 2040, 2045, and 2050, respectively corresponding to the Global Net-Zero scenario.

Dispersion characteristics of large-scale liquid hydrogen spills in a real-world liquid hydrogen refueling station with various releasing and environmental conditions

The global expansion of hydrogen refueling stations (HRS) has heightened interest in the development of liquid hydrogen refueling stations (LHRS). This study presents a model for an LHRS, inspired by the Yilan HRS in Shanghai, to simulate large-scale liquid hydrogen (LH2) leakage scenarios. Utilizing the FLACS-CFD software, comprehensive simulations were performed to assess the impact of various environmental conditions and leakage parameters—such as wind speed, wind direction, spill rate, and spill duration—on critical outcomes including the size of the LH2 pool, evaporation rate, flammable volume of the vaporized hydrogen gas cloud, and maximum downwind distance/height. The findings establish a correlation between these factors and the predicted results, providing real-time guidance for managing LH2 leakage incidents at operational LHRS.

Optimal design and three-level stochastic energy management for an interconnected microgrid with hydrogen production and storage for fuel cell electric vehicle refueling stations

A new trend in the transportation sector globally can be observed in a shift away from gasoline-powered vehicles to Hydrogen-based fuel-cell electric vehicles (FCEVs), aimed at reducing harmful emissions. However, there are challenges in producing hydrogen for vehicle stations related to microgrid design and energy management under uncertain conditions. This research sought to identify the optimum design of an electric microgrid to provide the required energy for electric loads, together with a hydrogen refueling station. The microgrid under study consists of various renewable energy resources (RERs), such as photovoltaic (PV) devices, wind power systems, and hydrogen storage systems. The energy management strategy (EMS) aims to reduce the total costs (investment, operation, replacement, procurement energy costs) considering four uncertain parameters associated with PV panels, FCEVs, wind turbines, and power demand. A three-level EMS is proposed based on testing various solutions: without RERs or a hydrogen energy storage system (Level 1); with RERs and a hydrogen energy storage system (Level 2), with RERs and hydrogen energy storage that includes demand side response (DSR) (Level 3). The results indicate annual cost savings of 1.946 E+06 $ for Level 2 and 2.001 E+06 $ for Level 3, compared to Level 1.

Cost-optimal design and operation of hydrogen refueling stations with mechanical and electrochemical hydrogen compressors

Hydrogen refueling stations (HRS) can cause a significant fraction of the hydrogen refueling cost. The main cost contributor is the currently used mechanical compressor. Electrochemical hydrogen compression (EHC) has recently been proposed as an alternative. However, its optimal integration in an HRS has yet to be investigated. In this study, we compare the performance of a gaseous HRS equipped with different compressors. First, we develop dynamic models of three process configurations, which differ in the compressor technology: mechanical vs. electrochemical vs. combined. Then, the design and operation of the compressors are optimized by solving multi-stage dynamic optimization problems. The optimization results show that the three configurations lead to comparable hydrogen dispensing costs, because the electrochemical configuration exhibits lower capital cost but higher energy demand and thus operating cost than the mechanical configuration. The combined configuration is a trade-off with intermediate capital and operating cost.

Operation of coupled power-gas networks with hydrogen refueling stations, responsive demands and storage systems: A novel stochastic framework

Because of factors such as low natural gas prices, low greenhouse gas emission and high efficiency has increased the penetration of natural gas-fired generators in electric power systems. Large gas consumption of gas-fired generators has caused intense interdependence of electricity and gas systems. Most often, the operational planning of power and gas systems is conducted through a co-optimisation model in which the total cost of electricity and gas systems is minimised and the constraints of both systems are considered. On the other hand, due to environmental concerns, the usage of fuel cell vehicles (FCVs) is increasing. Hydrogen refueling stations (HRSs) are needed for refueling FCVs. This paper puts forward a stochastic model for co-optimisation of wind-integrated power and gas systems, hosting HRSs, electric storage systems (ESS's) and responsive electricity and gas demands. The effect of ESS's, responsive demands, contingencies, wind uncertainties and demand response on operation of power-gas nexus is scrutinized. An incentive-based demand response program has been used for both electricity and gas demands. The case study is the Belgian gas network connected to the a 24-bus power system. The findings indicate that responsive electric demands reduce electric system cost by 9.4 %, while responsive gas demands reduce the gas network cost and total operation cost by 1 %. The contingency analysis on the power-gas nexus shows that single line outage contingencies in power system does not result in any demand shed and does not increase the operation cost of either electricity network or gas network.

An review of research on liquid hydrogen leakage: regarding China’s hydrogen refueling stations

Hydrogen is regarded as the premier energy source for future sustainability and renewability. However, its distinct physicochemical properties render it prone to explosions in the event of a leak. Therefore, there is a need for more comprehensive research dealing with hydrogen leakage, explosion scenarios, and risk assessment. This paper provides an overview of the current hydrogen policies adopted in China. It reviews the processes of hydrogen refueling station construction and the thermophysical mechanisms of liquid hydrogen leakage. In this regard, the effects of various factors, including leakage rate, leakage time, leakage hole size, wind direction and speed, and building location, on the hydrogen leakage rate are analyzed and evaluated. Additionally, the impacts of different factors on hydrogen explosion overpressure are reported, including hydrogen concentration, wind speed, obstacles, and ignition position, in addition to the current applications of quantitative risk assessment methods in hydrogen refueling stations. Finally, the limitations of current research on liquid hydrogen leakage and explosion accidents are highlighted, along with the shortcomings of current risk assessment methods for liquid hydrogen refueling stations.

Optimal design of concentrated solar power-based hydrogen refueling station: Mixed integer linear programming approach

This paper developed a mixed integer linear programming model to optimally design hydrogen refueling station coupled with an on-grid concentrated solar power. The model aims to minimize the total life cycle cost of the integrated system addressing various constraints. The utility of the proposed model is validated using hydrogen refueling station under the weather conditions of Dhahran city, Saudi Arabia. The station fulfills the daily hydrogen requirements of taxi-fleet in Dhahran city, estimating a daily demand of 4202 kg of hydrogen. The proposed hydrogen refueling station requires a solar field of 71,721 square meters to generate 50,233 MWh of energy annually. The on-grid concentrated solar power system is determined to produce an excess energy of 10,515 MWh which is exported to the grid, highlighting positive economic impact. The levelized cost of hydrogen of the proposed system is 7.17 $/kg. The achieved results validated the feasibility and efficiency of the proposed system, positioning it as a sustainable solution for meeting the rising demand for clean and green transportation in the region.