Node-based vs. path-based location models for urban hydrogen refueling stations: Comparing convenience and coverage abilities

For optimizing locations of hydrogen refueling stations, two popular approaches represent fuel demands as either nodes or paths, which imply different refueling behavior and definitions of convenience. This paper compares path-based vs. node-based models from the perspective of minimizing total additional travel time and feasibly covering all demands with the same number of stations. For this comparison, two new station location models are introduced that extend the Flow Capturing Location Model (FCLM) and p-Median Problem (PMP) by consistently defining upper limits on vehicle driving range and maximum inconvenience on refueling trips. Results for an idealized metropolitan area and Orlando, Florida show that path-based refueling substantially reduces wasteful travel time for refueling and covers more demand feasibly and more equitably in most scenarios. Path-based models incorporate the fact that residents of a zone regularly interact with other zones; therefore, individual stations can cover flows originating both near and far from their locations. This study suggests that path-based approaches to planning hydrogen refueling infrastructure enable more people in more neighborhoods to refuel fuel-cell vehicles without wasting excessive time or running out of fuel.     

Understanding the design and economics of distributed tri-generation systems for home and neighborhood refueling—Part I: Single family residence case studies

The potential benefits of hydrogen as a transportation fuel will not be achieved until hydrogen vehicles capture a substantial market share. However, although hydrogen fuel cell vehicle (FCV) technology has been making rapid progress, the lack of a hydrogen infrastructure remains a major barrier for FCV adoption and commercialization. The high cost of building an extensive hydrogen station network and the foreseeable low utilization in the near term discourages private investment. Based on the past experience of fuel infrastructure development for motor vehicles, innovative, distributed, small-volume hydrogen refueling methods may be required to refuel FCVs in the near term. Among small-volume refueling methods, home and neighborhood tri-generation systems (systems that produce electricity and heat for buildings, as well as hydrogen for vehicles) stand out because the technology is available and has potential to alleviate consumer's fuel availability concerns. In addition, it has features attractive to consumers such as convenience and security to refuel at home or in their neighborhood.The objective of this paper is to provide analytical tools for various stakeholders such as policy makers, manufacturers and consumers, to evaluate the design and the technical, economic, and environmental performances of tri-generation systems for home and neighborhood refueling. An interdisciplinary framework and an engineering/economic model is developed and applied to assess home tri-generation systems for single family residences (case studies on neighborhood systems will be provided in a later paper). Major tasks include modeling yearly system operation, exploring the optimal size of a system, estimating the cost of electricity, heat and hydrogen, and system CO₂ emissions, and comparing the results to alternatives. Sensitivity analysis is conducted, and the potential impacts of uncertainties in energy prices, capital cost reduction (or increase), government incentives and environmental cost are evaluated. Policy implications of the modeling results are also explored.     

Optimal siting and sizing of hydrogen refueling stations considering distributed hydrogen production and cost reduction for regional consumers

Hydrogen fuel cell vehicles are currently facing two difficulties in achieving their general use: the lack of hydrogen refueling stations and high hydrogen prices. Hydrogen refueling stations are the middle stage for delivering hydrogen from its sources to consumers, and their location could be affected by the distributed locations of hydrogen sources and consumers. The reasonable siting and sizing of hydrogen refueling stations could both improve the hydrogen infrastructure and reduce regional consumers' cost of using hydrogen. By considering the hydrogen life cycle cost and using a commercial volume forecasting model, this paper creates a relatively thorough and comprehensive model for hydrogen station siting and sizing with the objective of achieving the optimal costs for consumers using hydrogen. The cost‐based model includes the selection of the hydrogen sources, transportation methods, and storage methods, and thus, the hydrogen supply chain can also be optimized. A numerical example is established in Section 4 with the solution algorithm and results.     

Developing an infrastructure for hydrogen vehicles: a Southern California case study

We have examined the technical feasibility and economics of developing a hydrogen vehicle refueling infrastructure for a specific area where zero emission vehicles are being considered, Southern California. Potential hydrogen demands for zero emission vehicles are estimated. We then assess in detail several near term possibilities for producing and delivering gaseous hydrogen transportation fuel including: (1) hydrogen produced from natural gas in a large, centralized steam reforming plant, and truck delivered as a liquid to refueling stations; (2) hydrogen produced in a large, centralized steam reforming plant, and delivered via small scale hydrogen gas pipeline to refueling stations; (3) by-product hydrogen from chemical industry sources; (4) hydrogen produced at the refueling station via small scale steam reforming of natural gas; and (5) hydrogen produced via small scale electrolysis at the refueling station. The capital cost of infrastructure and the delivered cost of hydrogen are estimated for each hydrogen supply option. Hydrogen is compared to other fuels for fuel cell vehicles (methanol, gasoline) in terms of vehicle cost, infrastructure cost and lifecycle cost of transportation. Finally, we discuss possible scenarios for introducing hydrogen as a fuel for fuel cell vehicles.     

Addition of hydrogen refueling for fuel cell bus fleet to existing natural gas stations: A case study in Wuhan,China

Hydrogen refueling is an essential infrastructure for fuel cell vehicles, and currently, it appears to be a critical service needed to initiate the highly anticipated hydrogen economy in China. A practical selecting procedure of adding hydrogen refueling service to existing natural gas (NG) stations is proposed in this study. A case study in Wuhan, China, is established to assess the feasibility and future planning. The demand for hydrogen fuel and initial supply chain of hydrogen in Wuhan are estimated based on the deployment objective of fuel cell buses. The existing NG stations are evaluated based on 300 kg/day to determine whether they meet the hydrogen safety requirement using Google map or field investigation. The safety space requirement of the hydrogen refueling area on existing NG station is determined as 25.9 × 27.1 m². The optimal hydrogen refueling plan for fuel cell buses is calculated with multi‐objective analysis in economic, environmental, and safety aspects from the view of the hydrogen refueling supply chain. It is shown that adding hydrogen refueling stations to existing NG stations is feasible in technology, economics, regulation, and operation considerations. This study provides guidelines for building the hydrogen infrastructure for fuel cell buses at their early stage of commercial operation.     

Modeling operating modes,energy consumptions,and infrastructure requirements of fuel cell plug in hybrid electric vehicles using longitudinal geographical transportation data

The fuel cell plug in hybrid electric vehicle (FCPHEV) is a near-term realizable concept to commercialize hydrogen fuel cell vehicles (FCV). Relative to conventional FCVs, FCPHEVs seek to achieve fuel economy benefits through the displacement of hydrogen energy with grid-sourced electrical energy, and they may have less dependence on a sparse hydrogen fueling infrastructure. Through the simulation of almost 690,000 FCPHEV trips using geographic information system (GIS) data surveyed from a fleet of private vehicles in the Puget Sound area of Washington State, USA, this study derives the electrical and hydrogen energy consumption of various design and control variants of FCPHEVs. Results demonstrate that FCPHEVs can realize hydrogen fuel consumption reductions relative to conventional FCV technologies, and that the fuel consumption reductions increase with increased charge depleting range. In addition, this study quantifies the degree to which FCPHEVs are less dependent on hydrogen fueling infrastructure, as FCPHEVs can refuel with hydrogen at a lower rate than FCVs. Reductions in hydrogen refueling infrastructure dependence vary with control strategies and vehicle charge depleting range, but reductions in fleet-level refueling events of 93% can be realized for FCPHEVs with 40 miles (60 km) of charge depleting range. These fueling events occur on or near the network of highways at approximately 4% of the rate (refuelings per year) of that for conventional FCVs. These results demonstrate that FCPHEVs are a type of FCV that can enable an effective and concentrated hydrogen refueling network.     

Analysis of a “cluster” strategy for introducing hydrogen vehicles in Southern California

The cost and logistics of building early hydrogen refueling infrastructure are key barriers to the commercialization of fuel cell vehicles. In this paper, we explore a “cluster strategy” for introducing hydrogen vehicles and refueling infrastructure in Southern California over the next decade, to satisfy California's Zero Emission Vehicle regulation. Clustering refers to coordinated introduction of hydrogen vehicles and refueling infrastructure in a few focused geographic areas such as smaller cities (e.g. Santa Monica, Irvine) within a larger region (e.g. Los Angeles Basin). We analyze several transition scenarios for introducing hundreds to tens of thousands of vehicles and 8–42 stations, considering:     

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.     

Manufacturing competitiveness analysis for hydrogen refueling stations

Fuel cell electric vehicles (FCEVs) have now entered the market as zero-emission vehicles. Original equipment manufacturers such as Toyota, Honda, and Hyundai have released commercial cars in parallel with efforts focusing on the development of hydrogen refueling infrastructure to support new FCEV fleets. Persistent challenges for FCEVs include high initial vehicle cost and the availability of hydrogen stations to support FCEV fleets. This study sheds light on the factors that drive manufacturing competitiveness of the principal systems in hydrogen refueling stations, including compressors, storage tanks, precoolers, and dispensers. To explore major cost drivers and investigate possible cost reduction areas, bottom-up manufacturing cost models were developed for these systems. Results from these manufacturing cost models show there is substantial room for cost reductions through economies of scale, as fixed costs can be spread over more units. Results also show that purchasing larger quantities of commodity and purchased parts can drive significant cost reductions. Intuitively, these cost reductions will be reflected in lower hydrogen fuel prices. A simple cost analysis shows there is some room for cost reduction in the manufacturing cost of the hydrogen refueling station systems, which could reach 35% or more when achieving production rates of more than 100 units per year. We estimated the potential cost reduction in hydrogen compression, storage and dispensing as a result of capital cost reduction to reach 5% or more when hydrogen refueling station systems are produced at scale.     

Risk assessment for liquid hydrogen fueling stations

In recent years, consumers calling for the protection of the environment on a regional and global scale are demanding the use of vehicles that do not emit harmful exhaust. It is anticipated that one response to this demand is the widespread use of fuel cell vehicles (FCVs). In order to achieve this, it is necessary to provide hydrogen fueling stations where FCVs can refuel.     

The deviation-flow refueling location model for optimizing a network of refueling stations

This research develops and applies a mixed-integer linear programming model that optimizes the locations of fueling stations considering not only the limited driving range of vehicles but also the necessary deviations that drivers are likely to make from their shortest paths in order to refuel their vehicles when the refueling station network is sparse. The Deviation-Flow Refueling Location Model (DFRLM) locates facilities to maximize the total flows refueled on deviation paths. The flow demand captured by the stations is assumed to decrease as the deviation that drivers must make increases. Test results indicate that the maximum allowable deviation and the specific deviation penalty functional form do have a measurable effect on the optimal locations of facilities and objective function values as well.     

Refueling availability for alternative fuel vehicle markets: Sufficient urban station coverage

Alternative fuel vehicles can play an important role in addressing the challenges of climate change, energy security, urban air pollution and the continued growth in demand for transportation services. The successful commercialization of alternative fuels for vehicles is contingent upon a number of factors, including vehicle cost and performance. Among fuel infrastructure issues, adequate refueling availability is one of the most fundamental to successful commercialization. A commonly cited source reports 164,300 refueling stations in operation nationwide. However, from the perspective of refueling availability, this nationwide count tends to overstate the number of stations required to support the widespread deployment of alternative fuel vehicles. In terms of spatial distribution, the existing gasoline station networks in many urban areas are more than sufficient. We characterize a sufficient level of urban coverage based upon a subset of cities served by relatively low-density station networks, and estimate that some 51,000 urban stations would be required to provide this sufficient level of coverage to all major urban areas, 33 percent less than our estimate of total urban stations. This improved characterization will be useful for engineering, economic and policy analyses.     

Understanding attitudes of hydrogen fuel-cell vehicle adopters in Japan

As of January 2021, Japan had the world's largest hydrogen station network with merely 4600 hydrogen fuel-cell vehicles (HFCVs) on roads, as compared to the 9000 HFCVs in the US, with only one-third of the hydrogen refueling stations in Japan. To understand behavioral differences among Japanese adopters, we administered a survey, in cooperation with public and private sector stakeholders, involving 89 private HFCV adopters in the Aichi Prefectural region, which hosts the largest number of HFCVs and refueling stations in Japan. Results suggest that HFCV adopters have a higher socioeconomic status than non-adopters, are mostly male in their 50s and above, and have a higher interest in new vehicle fuel technology. HFCV adopters who leased and bought vehicles were similar in terms of socioeconomic status, with differences in attitudes toward governmental incentives. The lack of refueling stations and station business hours restrict HFCV adopters from continuing with this fuel technology.     

Hydrogen fuel cell electric vehicle performance and user-response assessment: Results of an extended driver study

This study examined driver acceptance and performance of hydrogen fuel cell electric vehicles as tested in real-world conditions over a two-year period. The study sample was a volunteer group of “n = 54” drivers who drove the vehicle for a month-long trial period. Each driver took ‘before’ and ‘after’ surveys regarding their driving experience. Drivers drove an average of 1400 miles per month, and either witnessed and/or performed vehicle refueling 3–10 times during their test period.Key findings from the study include that: 1) 80% of study participant drivers found that the fuel cell vehicle (FCV) performance “exceeded” or “greatly exceeded” their expectations; 2) 98% of study participant drivers view hydrogen as a fuel for vehicles as being “as safe” or “safer” than gasoline as a fuel for vehicles; and 3) 94% of participants view the process of fueling a vehicle with hydrogen to be “as safe” or “safer” than gasoline fueling. Other findings include that 85% of study participants who performed their own fueling described hydrogen fueling to be “somewhat” or “very” simple. Of the participants, 62% percent had to forgo at least one trip due to lack of hydrogen fuel, although vehicle range was rated by 75% of participants as entirely or mostly adequate. If fueling infrastructure availability was not an issue, and fuel cost per-mile was at parity with gasoline, 75% of participants would be willing to pay $40,000 or less for an FCV.     

A solution to renewable hydrogen economy for fuel cell buses – A case study for Zhangjiakou in North China

Fuel cell vehicles fueled with renewable hydrogen is recognized as a life-cycle carbon-free option for the transport sector, however, the profitability of the H₂ pathway becomes a key issue for the FCV commercialization. By analyzing the actual data from the Zhangjiakou fuel cell transit bus project, this research reveals it is economically feasible to commercialize FCV in areas with abundant renewable resources. Low electricity for water electrolysis, localization of H₂ supply, and curtailed end price of H₂ refueling effectively reduce the hydrogen production, delivery and refueling cost, and render a chance for the profitability of refueling stations. After the fulfillment of the intense deployment of both vehicles and hydrogen stations for the 2022 Winter Olympics, the H₂ pathway starts to make a profit thereafter. The practices in the Zhangjiakou FCB project offer a solution to the hydrogen economy, which helps to break the chicken-egg dilemma of vehicles and hydrogen infrastructure.     

Optimization of hydrogen stations in Florida using the Flow-Refueling Location Model

This paper develops and applies a model that locates hydrogen stations to refuel the maximum volume of vehicle flows. Inputs to the model include a road network with average speeds; the origin–destination flow volumes between each origin and destination; a maximum driving range between refueling stops; and the number of stations to build. The Flow-Refueling Location Model maximizes the flow volumes that can be refueled, measured either in number of trips or vehicle-miles traveled. Geographic Information Systems and heuristic algorithms are integrated in a spatial decision support system that researchers can use to develop data, enter assumptions, analyze scenarios, evaluate tradeoffs, and map results. For the Florida Hydrogen Initiative, we used this model to investigate strategies for rolling out an initial refueling infrastructure in Florida at two different scales of analysis: metropolitan Orlando and statewide. By analyzing a variety of scenarios at both scales of analysis, we identify a robust set of stations that perform well under a variety of assumptions, and develop a strategy for phasing in clustered and connecting stations in several stages or tiers.     

Near-term location planning of hydrogen refueling stations in Yokohama City

Establishing hydrogen refueling stations is key to transition into a hydrogen economy. To achieve this, a near-term, city-level roll-out plan is required, as Japan is shifting from the demonstration to implementation stage of a hydrogen economy. The aim of this study was to devise a plan to identify near-term locations to build hydrogen refueling stations in Yokohama City, Japan. Our plan provides information on the potential location of hydrogen refueling stations for 2020–2030. We considered mobile and parallel-siting type refueling stations; the locations of these stations were determined by matching the supply and demand estimated from hybrid vehicle ownership data and the available space in existing gas stations based on a safety perspective. The results reaffirmed the importance of planning the locations of hydrogen refueling stations and highlighted the suitability of using mobile-type stations. This was based on the uncertainty in fuel demand for fuel cell vehicles during the implementation stage of the hydrogen economy.     

Improving hydrogen refueling stations to achieve minimum refueling costs for small bus fleets

Fuel cell vehicles using green hydrogen as fuel can contribute to the mitigation of climate change. The increasing utilization of those vehicles creates the need for cost efficient hydrogen refueling stations. This study investigates how to build the most cost efficient refueling stations to fuel small fleet sizes of 2, 4, 8, 16 and 32 fuel cell busses. A detailed physical model of a hydrogen refueling station was built to determine the necessary hydrogen storage size as well as energy demand for compression and precooling of hydrogen. These results are used to determine the refueling costs for different station configurations that vary the number of storage banks, their volume and compressor capacity.It was found that increasing the number of storage banks will decrease the necessary total station storage volume as well as energy demand for compression and precooling. However, the benefit of adding storage banks decreases with each additional bank. Hence the cost for piping and instrumentation to add banks starts to outweigh the benefits when too many banks are used. Investigating the influence of the compressor mass flow found that when fueling fleets of 2 or 4 busses the lowest cost can be reached by using a compressor with the minimal mass flow necessary to refill all storage banks within 24 h. For fleets of 8, 16 and 32 busses, using the compressor with the maximum investigated mass flow of 54 kg/h leads to the lowest costs.     

Thermodynamic modeling of hydrogen refueling for heavy-duty fuel cell buses and comparison with aggregated real data

The foreseen uptake of hydrogen mobility is a fundamental step towards the decarbonization of the transport sector. Under such premises, both refueling infrastructure and vehicles should be deployed together with improved refueling protocols. Several studies focus on refueling the light-duty vehicles with 10 kg_H2 up to 700 bar, however less known effort is reported for refueling heavy-duty vehicles with 30–40 kg_H2 at 350 bar. The present study illustrates the application of a lumped model to a fuel cell bus tank-to-tank refueling event, tailored upon the real data acquired in the 3Emotion Project. The evolution of the main refueling quantities, such as pressure, temperature, and mass flow, are predicted dynamically throughout the refueling process, as a function of the operating parameters, within the safety limits imposed by SAE J2601/2 technical standard. The results show to refuel the vehicle tank from half to full capacity with an Average Pressure Ramp Rate (APRR) equal to 0.03 MPa/s are needed about 10 min. Furthermore, it is found that the effect of varying the initial vehicle tank pressure is more significant than changing the ambient temperature on the refueling performances. In conclusion, the analysis of the effect of different APRR, from 0.03 to 0.1 MPa/s, indicate that is possible to safely reduce the duration of half-to-full refueling by 62% increasing the APRR value from 0.03 to 0.08 MPa/s.     

On optimal investment strategies for a hydrogen refueling station

The uncertainty and cost of changing from a fossil-fuel-based society to a hydrogen-based society are considered to be extensive obstacles to the introduction of fuel cell vehicles (FCVs). The absence of existing profitable refueling stations has been shown to be one of the major barriers. This paper investigates methods for calculating an optimal transition from a gasoline refueling station to future methane and hydrogen combined use with an on site small-scale reformer for methane. In particular, we look into the problem of matching the hydrogen capacity of a single refueling station to an increasing demand. Based on an assumed future development scenario, optimal investment strategies are calculated. First, a constant utilization of the hydrogen reformer is assumed in order to find the minimum hydrogen production cost. Second, when considerations such as periodic maintenance are taken into account, optimal control is used to concurrently find both a short term equipment variable utilization for one week and a long term strategy. The result is a minimum hydrogen production cost of $4–6/kg, depending on the number of reinvestments during a 20 year period. The solution is shown to yield minimum hydrogen production cost for the individual refueling station, but the solution is sensitive to variations in the scenario parameters.