Development of Korean hydrogen fueling station codes through risk analysis

When hydrogen fueling stations were constructed first time in Korea in 2006, there were no standards for hydrogen fueling stations. Hence the CNG (Compressed Natural Gas) station codes were temporarily adopted. In last three years, from 2006 to 2009, the studies for the development of hydrogen fueling station standards were carried out, with the support of the Korean government. In this study, three research groups cooperated to develop optimized hydrogen fueling station codes through risk analysis of hydrogen production and filling systems. Its results were integrated to develop the codes. In the first step to develop the codes, the standards for CNG stations and hydrogen fueling station were compared with each other and analyzed. By referring to foreign hydrogen fueling station standards, we investigated the potential problems in developing hydrogen fueling station codes based on the CNG station standards. In the second, the results of the high-pressure hydrogen leakage experiment were analyzed, and a numerical analysis was performed to establish the safety distance from the main facilities of a hydrogen fueling station to the protection facilities. In the third, HAZOP (Hazard and Operability) and FTA (Fault Tree Analysis) safety assessments were carried out for the on-site and off-site hydrogen fueling stations—currently being operated in Korea— to analyze the risks in existing hydrogen fueling stations. Based on the study results of the above three groups, we developed one codes for off-site type hydrogen fueling stations and another codes for on-site type hydrogen fueling stations. These were applied from September 2010.     

Identification of public acceptance factors with risk perception scales on hydrogen fueling stations in Japan

This is the first work to describe the characteristics of public acceptance of hydrogen stations (H2 station) in Japan using risk perception scales. We conducted an online survey asking respondents to rate their acceptance of having an H2 station constructed in the gas station nearest their home. Sixty-six percent of respondents indicated a high rate of acceptance, with males tending to be more accepting than females, irrespective of age. We found the following to be explanatory factors for acceptance: gender, degree, vehicle use, knowledge about hydrogen, risk perception of H2 station, and inherent risk acceptance and avoidance. Binominal regression analysis was used to construct an acceptance model, and the risk perception factor “Dread” was dominant among the effective independent variables. This suggests that alleviating inherent dread or fear by providing precise risk information will lead to better acceptance. Our study contributes to improved risk communication on H2 station construction.     

Economic competitiveness of compact steam methane reforming technology for on-site hydrogen supply: A Foshan case study

On-site hydrogen production through steam-methane reforming (SMR) from city gas or natural gas is believed to be a cost-effective way for hydrogen-based infrastructure due to high cost of hydrogen transportation. In recent years, there have been a lot of on-site hydrogen fueling stations under design or construction in China. This study introduces current developments and technology prospects of skid-mounted SMR hydrogen generator. Also, technical solutions and economic analysis are discussed based on China's first on-site hydrogen fueling station project in Foshan. The cost of hydrogen product from skid-mounted SMR hydrogen generator is about 23 CNY/kg with 3.24 CNY/Nm³ natural gas. If hydrogen price is 60 CNY/kg, IRR of on-site hydrogen fueling station project reaches to 10.8%. While natural gas price fall to 2.3 CNY/Nm³, the hydrogen cost can be reduced to 18 CNY/kg, and IRR can be raised to 13.1%. The conclusion is that skid-mounted SMR technology has matured and is developing towards more compact and intelligent design, and will be a promising way for hydrogen fueling infrastructures in near future.     

An integrated quantitative-qualitative study to monitor the utilization and assess the perception of hydrogen fueling stations

Zero-emission vehicle (ZEV) adoption is one of the critical solutions to decarbonize the transportation sector. Among the ZEV fleet in the US, battery electric vehicles (BEV) have been leading the market penetration. However, hydrogen fuel cell electric vehicles (FCEV) have also been increasingly adopted in recent years. Although both technologies have challenges with infrastructure, unlike BEVs that have multiple venues for charging (home, work or public), FCEVs rely solely on fueling at public hydrogen stations, and their availability is a significant factor before the vehicle purchase. Therefore, for the success of FCEV adoption, a need to monitor and understand the driver satisfaction of these stations is extremely critical. This research project introduces a quantitative-qualitative approach for continuous monitoring of hydrogen stations based on the station utilization patterns and to assess their preferability based on driver experiences. To illustrate a proof-of-concept, we collected the hourly utilization data of all the hydrogen fueling stations in California for three months. The time-series data was used to develop a capacity-independent term called “Normalized Relative Utilization Index” (NRUI) that encapsulates the utilization pattern of each station to a single metric. We spatially regressed this metric over the number of FCEVs present in the neighborhood to deduce the relationship. We designed a survey to obtain the refueling experiences of FCEV drivers, where about 100 participants responded with their station preferences. Their answers were used to validate the quantitative approach and identify a “Satisfactory Utilization Range” (SUR) of stations which are preferred by most drivers. Though this project illustrates the analysis of data collected over a small period, this approach is easily scalable with new station installations and can be implemented as a continuous monitoring system with real-time station utilization data. We believe this demand-focused approach could complement the existing supply-side monitoring methods on station performance to provide a smoother fueling experience to drivers. We are also releasing the hourly station capacity dataset that was collected as a part of this study to the research community.     

Analysis of customer queuing at hydrogen stations

An analysis is presented of service rates at nineteen retail hydrogen stations in a heavily-used California network to gain insight into station capacity impacts on customer wait times. Each station has only one fueling position resulting from just one, one-sided dispenser. Collected data of each refueling step for 1000's of hydrogen refuelings in California provides insight into station and network capacity for both California and emerging infrastructure elsewhere. The analysis herein concludes that customers would be exponentially better served with a network of larger, multi-position stations instead of smaller, one position stations.     

Simulation of hydrogen leak and explosion for the safety design of hydrogen fueling station in Korea

Hydrogen has been used as chemicals and fuels in industries for last decades. Recently, it has become attractive as one of promising green energy candidates in the era of facing with two critical energy issues such as accelerating deterioration of global environment (e.g. carbon dioxide emissions) as well as concerns on the depletion of limited fossil sources. A number of hydrogen fueling stations are under construction to fuel hydrogen-driven vehicles. It would be indispensable to ensure the safety of hydrogen station equipment and operating procedure in order to prevent any leak and explosions of hydrogen: safe design of facilities at hydrogen fueling stations e.g. pressurized hydrogen leak from storage tanks. Several researches have centered on the behaviors of hydrogen ejecting out of a set of holes of pressurized storage tanks or pipes. This work focuses on the 3D simulation of hydrogen leak scenario cases at a hydrogen fueling station, given conditions of a set of pressures, 100, 200, 300, 400 bar and a set of hydrogen ejecting hole sizes, 0.5, 0.7, 1.0 mm, using a commercial computational fluid dynamics (CFD) tool, FLACS. The simulation is based on real 3D geometrical configuration of a hydrogen fueling station that is being commercially operated in Korea. The simulation results are validated with hydrogen jet experimental data to examine the diffusion behavior of leak hydrogen jet stream. Finally, a set of marginal safe configurations of fueling facility system are presented, together with an analysis of distribution characteristics of blast pressure, directionality of explosion. This work can contribute to marginal hydrogen safety design for hydrogen fueling stations and a foundation on establishing a safety distance standard required to protect from hydrogen explosion in Korea being in the absence of such an official requirement.     

Liquid pump-enabled hydrogen refueling system for medium and heavy duty fuel cell vehicles: Station design and technoeconomic assessment

Recent progress in submerged liquid hydrogen (LH₂) cryopump technology development offers improved hydrogen fueling performance at a reduced cost in medium- and heavy-duty (MDV and HDV) fuel cell vehicle refueling applications at 35 MPa pressure, compared to fueling via gas compression. In this paper, we evaluate the fueling cost associated with cryopump-based refueling stations for different MDV and HDV hydrogen demand profiles. We adapt the Heavy Duty Refueling Station Analysis Model (HDRSAM) tool to analyze the submerged cryopump case, and compare the estimated fuel dispensing costs of stations supplied with LH₂ for fueling Class 4 delivery van (MDV), public transit bus (HDV), and Class 8 truck (HDV) fleets using cryopumps relative to station designs. A sensitivity analysis around upstream costs illustrates the trade-offs associated with H₂ production from onsite electrolysis versus central LH₂ production and delivery. Our results indicate that LH₂ cryopump-based stations become more economically attractive as the total station capacity (kg dispensed per day) and hourly demand (vehicles per hour) increase. Depending on the use case, savings relative to next best options range from about 5% up to 44% in dispensed costs, with more favorable economics at larger stations with high utilization.     

Predicting demand for hydrogen station fueling

Full function hydrogen stations are a reality; fuel cell electric vehicle drivers can pull up to commercial fueling stations and receive 3–5 kg in less than 5 min, for an approximately 300-mile range. The demand for hydrogen is increasing, driven by an increase in the fueling of public and private fuel cell vehicles. This study describes the development and value of a model that simulates stochastic future demand at a hydrogen filling station. The predictive hydrogen demand model described in this article is trained from mathematical models constructed from actual hydrogen fill count, amount, and frequency data. Future fill probabilities inform the hour-by-hour demand profile and the station state of either “available, ready to fill” or “available, filling”. For example, a prediction for a station generally dispensing 5,000 kg a week on a Friday afternoon at 4 p.m. is 16 fills, totaling 48.7 kg, with a 0.52 proportion of time spent in “available, filling” state yielding 31 min of filling time. This is a first-of-its kind, published study on predicting future hydrogen demand by the time of day (e.g., hour-by-hour intervals) and day of week. This study can be used for hydrogen station requirements and operation and maintenance strategies and to assess the impact of demand variations and scenarios. This article presents the current status of hydrogen demand, the model development methods, a set of sample results. Discussion and conclusions concentrate on the value and use of the proposed model.     

Review of transportation hydrogen infrastructure performance and reliability

Hydrogen infrastructure for fueling vehicles has progressed in the last decade from stations with restricted access and limited operating hours to customer-friendly retail stations open to the public. There are now 121 retail hydrogen stations around the world. In California, the number of public retail hydrogen stations has increased from zero to more than 30 in less than two years, and the annual amount of hydrogen dispensed by retail stations has grown from 27,400 kg in 2015 to nearly 105,000 kg in 2016 and more than 440,000 kg in 2017—an increase of about four times year over year. For more than a decade, government, industry, and academia have studied many aspects of hydrogen infrastructure, from renewable hydrogen production to retail hydrogen station performance. This paper reviews the engineering and deployment of modern hydrogen infrastructure, including the costs, benefits, and operational considerations (including safety, reliability, availability), as well as challenges to the scale-up of hydrogen infrastructure. The results identify hydrogen station reliability as a key factor in the expense of operating hydrogen systems, placing it in the context of the larger reliability engineering field.     

Projecting full build-out environmental impacts and roll-out strategies associated with viable hydrogen fueling infrastructure strategies

A transition from gasoline internal combustion engine vehicles to hydrogen fuel cell electric vehicles (FCEVs) is likely to emerge as a major component of the strategy to meet future greenhouse gas reduction, air quality, fuel independence, and energy security goals. Advanced infrastructure planning can minimize the cost of hydrogen infrastructure while assuring that energy and environment benefits are achieved. This study presents a comprehensive advanced planning methodology for the deployment of hydrogen infrastructure, and applies the methodology to delineate fully built-out infrastructure strategies, assess the associated energy and environment impacts, facilitate the identification of an optimal infrastructure roll-out strategy, and identify the potential for renewable hydrogen feedstocks. The South Coast Air Basin of California, targeted by automobile manufacturers for the first regional commercial deployment of FCEVs, is the focus for the study. The following insights result from the application of the methodology:

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Compared to current gasoline stations, only 11%-14% of the number of hydrogen fueling stations can provide comparable accessibility to drivers in a targeted region.

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To meet reasonable capacity demand for hydrogen fueling, approximately 30% the number of hydrogen stations are required compared to current gasoline stations.

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Replacing gasoline vehicles with hydrogen FCEVs has the potential to (1) reduce the emission of greenhouse gases by more than 80%, reduce energy requirements by 42%, and virtually eliminate petroleum consumption from the passenger vehicle sector, and (2) significantly reduce urban concentrations of ozone and PM2.5.

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Existing sources of biomethane in the California South Coast Air Basin can provide up to 30% of the hydrogen fueling demand for a fully built-out hydrogen FCEV scenario.

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A step-wise transition of judiciously located existing gasoline stations to dispense and accommodate the increasing demand for hydrogen addresses proactively key infrastructure deployment challenges including a viable business model, zoning, permitting, and public acceptance.

     

Analysis of a hydrogen station roll-out strategy to introduce hydrogen vehicles in Andalusia

The issue of the distribution of a sufficient infrastructure of hydrogen fueling stations to enable meeting of the initial demand and to satisfy the different roll-out scenarios has been addressed by different authors, in different geographies, and with different methods and approaches. In this paper, we use a spatial approach to study the prospect of a sequential roll-out strategy from the present time to 2030 for Andalusia, a region in southern Spain. In every stage, we identify main nodes and clusters by examining in which areas of this region the roll-out of fueling stations should start. Finally, we estimate the number and size of fueling stations for every stage, as well as the investment required for this infrastructure roll-out based on the estimated costs for each type of hydrogen fueling station over the aforesaid time.     

Using AHP and binary integer programming to optimize the initial distribution of hydrogen infrastructures in Andalusia

The use of vehicles powered by hydrogen from renewable sources can be a viable alternative for Andalusia, given its accessibility to renewable energies and the problems of energy dependence and pollution resulting from the current energy model. However, the introduction of this type of technology requires an initial infrastructure that solves the classical chicken and egg problem. Given that hydrogen fueling infrastructure will require significant initial capital investment, it is reasonable to assume that a possible strategy of introduction could be the establishment of a station network that is sparse to avoid redundancy and therefore minimize costs. In this paper, we utilize Analytic Hierarchy Process to rank, on the basis of several supply, demand and environmental criteria, the more than 750 municipalities of Andalusia according to their suitability for the establishment of hydrogen fueling stations. Subsequently, we incorporate these results into an optimization problem to achieve optimal planning of the number and location of hydrogen fueling stations to provide coverage for the region.     

Development of a web-based 3D virtual reality program for hydrogen station

The hydrogen fueling station is an infrastructure of supplying fuel cell vehicles. It is necessary to guarantee the safety of hydrogen station equipment and operating procedure for decreasing intangible awareness of danger of hydrogen. Among many methods of securing the safety of the hydrogen stations, the virtual experience by dynamic simulation of operating the facilities and equipment is important. Thus, we have developed a virtual reality operator education system, and an interactive hydrogen safety training system. This paper focuses on the development of a virtual reality operator education of the hydrogen fueling station based on simulations of accident scenarios and hypothetical operating experience. The risks to equipment and personnel, associated with the manual operation of hydrogen fueling station demand rigorous personnel instruction. Trainees can practice how to use all necessary equipments and can experience twenty possible accident scenarios. This program also illustrates Emergency Response Plan and Standard Operating Procedure for both emergency and normal operations.     

Quantitative analysis of a successful public hydrogen station

Reliable hydrogen fueling stations will be required for the successful commercialization of fuel cell vehicles. An evolving hydrogen fueling station has been in operation in Irvine, California since 2003, with nearly five years of operation in its current form. The usage of the station has increased from just 1000 kg dispensed in 2007 to over 8000 kg dispensed in 2011 due to greater numbers of fuel cell vehicles in the area. The station regularly operates beyond its design capacity of 25 kg/day and enables fuel cell vehicles to exceed future carbon reduction goals today. Current limitations include a cost of hydrogen of $15 per kg, net electrical consumption of 5 kWh per kg dispensed, and a need for faster back-to-back vehicle refueling.     

Security risk analysis of a hydrogen fueling station with an on-site hydrogen production system involving methylcyclohexane

Although many studies have looked at safety issues relating to hydrogen fueling stations, few studies have analyzed the security risks, such as deliberate attack of the station by threats such as terrorists and disgruntled employees. The purpose of this study is to analyze security risks for a hydrogen fueling station with an on-site production of hydrogen from methylcyclohexane. We qualitatively conducted a security risk analysis using American Petroleum Institute Standard 780 as a reference for the analysis. The analysis identified 93 scenarios, including pool fires. We quantitatively simulated a pool fire scenario unique to the station to analyze attack consequences. Based on the analysis and the simulation, we recommend countermeasures to prevent and mitigate deliberate attacks.     

Risk assessment of Hydrogen fueling stations for 70 MPa FCVs

People are placing their hopes on the future of fuel-cell vehicles (FCVs) to replace today's gasoline-fueled vehicles. To encourage the widespread use of FCVs, however, these vehicles must be able to drive a distance of at least 500 km, mileage comparable to today's gasoline-fueled vehicles. To achieve this distance, automobile manufacturers are focusing their efforts on developing new hydrogen fuel tanks that will raise pressure to 70 MPa from the current 35 MPa. At the same time, hydrogen stations will also have to be able to provide 70 MPa compressed hydrogen gas to service these improved FCVs. Regulations for hydrogen fueling stations where pressure is no higher than 40 MPa were established in 2005 in Japan but it goes without saying that these regulations are inadequate for hydrogen fueling stations of 70 MPa.     

Energetic evaluation of hydrogen refueling stations with liquid or gaseous stored hydrogen

The future success of fuel cell electric vehicles requires a corresponding infrastructure. In this study, two different refueling station concepts for fuel cell passenger cars with 70 MPa technology were evaluated energetically. In the first option, the input of the refueling station is gaseous hydrogen which is compressed to final pressure, remaining in gaseous state. In the second option, the input is liquid hydrogen which is cryo-compressed directly from the liquid phase to the target pressure. In the first case, the target temperature of −33 °C to −40 °C [1] is achieved by cooling down. In the second option, gaseous deep-cold hydrogen coming from the pump is heated up to target temperature. A dynamic simulation model considering real gas behavior to evaluate both types of fueling stations from an energetic perspective was created. The dynamic model allows the simulation of boil-off losses (liquid stations) and standby energy losses caused by the precooling system (gaseous station) dependent on fueling profiles. The functionality of the model was demonstrated with a sequence of three refueling processes within a short time period (high station utilization). The liquid station consumed 0.37 kWh/kg compared to 2.43 kWh/kg of the gaseous station. Rough estimations indicated that the energy consumption of the entire pathway is higher for liquid hydrogen. The analysis showed the high influence of the high-pressure storage system design on the energy consumption of the station. For future research work the refueling station model can be applied to analyze the energy consumption dependent on factors like utilization, component sizing and ambient temperature.     

Thermodynamic modeling of hydrogen fueling process from high-pressure storage tank to vehicle tank

This study develops a hydrogen fueling station (HFS) thermodynamic model that simulates the actual fueling process in which hydrogen is supplied from a high-pressure (HP) storage tank into a fuel cell electric vehicle (FCEV) tank. To make the model as accurate as possible, we use the same components and specifications as in actual HFSs, such as a pressure control valve, a pre-cooling system, and an FCEV tank. After the components and their specifications are set, pressure and temperature profiles are set as the HP tank supply conditions. Based on the pressure and temperature profiles, the model solves for the temperature, pressure, and mass flow rate of hydrogen at each downstream position, including the inside of the vehicle tank. The values predicted by the model are compared with experimental data, and we show that the developed model makes it possible to accurately simulate those values at any position during the fueling process.     

Thermodynamic parametric analysis of refueling heavy-duty hydrogen fuel-cell electric vehicles

Reliable design and safe operation of heavy-duty hydrogen refueling stations are essential for the successful deployment of heavy-duty fuel cell electric vehicles (FCEVs). Fueling heavy-duty FCEVs is different from light-duty vehicles in terms of the dispensed hydrogen quantities and fueling rates, requiring tailored fueling station design for each vehicle class. In particular, the selection and design of the onboard hydrogen storage tank system and the fueling performance requirements influence the safe design of hydrogen fueling stations. A thermodynamic modeling and analysis are performed to evaluate the impact of various fueling parameters and boundary conditions on the fueling performance of heavy-duty FCEVs. We studied the effect of dispenser pressure ramp rate and precooling temperature, initial tank temperature and pressure, ambient temperature, and onboard storage design parameters, such as onboard storage pipe diameter and length, on the fueling rate and final vehicle state-of-charge, while observing prescribed tank pressure and temperature safety limits. An important finding was the sensitivity of the temporal fueling rate profile and the final tank state of charge to the design factors impacting pressure drop between the dispenser and vehicle tank, including onboard storage pipe diameter selection, and flow coefficients of nozzle, valves, and fittings. The fueling rate profile impacts the design and cost of the hydrogen precooling unit upstream of the dispenser.     

Overall efficiency comparison between the fueling methods of SAEJ2601 using dynamic simulations

This study concerns MC Formula and the table-based protocol hydrogen fueling methods described in SAE J2601 2016 edition fueling protocols for light duty gaseous hydrogen surface vehicles. It considers the overall efficiency and performance of the two methods. This is achieved by dynamic simulations, using the Dymola hydrogen fueling station library. The MC formula and table-based methods are implemented in the library and different simulations are performed, to evaluate the performance of the two different fueling methods under various conditions. The efficiency is evaluated according to; fueling time, State of Charge levels and total energy consumption. The MC formula is up to 26% faster. The state of charge levels are similar between the table-based and MC formula. The energy consumption for the MC formula is up to 6.9% higher than for the table-based method. Comparing consecutive fuelings without recharging the station, the table-based method is able to fill 7 vehicles and the MC formula 5 vehicles.