Impact of hydrogen SAE J2601 fueling methods on fueling time of light-duty fuel cell electric vehicles

Hydrogen fuel cell electric vehicles (HFCEVs) are zero-emission vehicles (ZEVs) that can provide drivers a similar experience to conventional internal combustion engine vehicles (ICEVs), in terms of fueling time and performance (i.e. power and driving range). The Society of Automotive Engineers (SAE) developed fueling protocol J2601 for light-duty HFCEVs to ensure safe vehicle fills while maximizing fueling performance. This study employs a physical model that simulates and compares the fueling performance of two fueling methods, known as the “lookup table” method and the “MC formula” method, within the SAE J2601 protocol. Both the fueling methods provide fast fueling of HFCEVs within minutes, but the MC formula method takes advantage of active measurement of precooling temperature to dynamically control the fueling process, and thereby provides faster vehicle fills. The MC formula method greatly reduces fueling time compared to the lookup table method at higher ambient temperatures, as well as when the precooling temperature falls on the colder side of the expected temperature window for all station types. Although the SAE J2601 lookup table method is the currently implemented standard for refueling hydrogen fuel cell vehicles, the MC formula method provides significant fueling time advantages in certain conditions; these warrant its implementation in future hydrogen refueling stations for better customer satisfaction with fueling experience of HFCEVs.     

Effect of cascade storage system topology on the cooling energy consumption in fueling stations for hydrogen vehicles

One of the main obstacles of the diffusion of fuel cell electric vehicles (FCEV) is the refueling system. The new stations follow the refueling protocol from the Society of Automotive Engineers where the way to reach the target pressure is not explained. This work analyzes the thermodynamics of a hydrogen fueling station in order to study the effects of the cascade storage system topology on the energy consumption for the cooling facility. It is found that the energy consumption for cooling increases, expanding the total volume of the cascade storage system. Comparing the optimal and the worst volume configurations of the cascade storage tanks at different ambient temperatures, the energy saving is approximately 12% when the average ambient temperature is 20 °C and around 20% when the average ambient temperature is 30 °C. The energy consumption for cooling is significantly influenced by the topology of the cascade storage system and it is particularly relevant in the case of low daily-dispensed amount of hydrogen.     

Optimization of hydrogen vehicle refueling via dynamic simulation

A dynamic model has been developed to analyze and optimize the thermodynamics and design of hydrogen refueling stations. The model is based on Dymola software and incorporates discrete components. Two refueling station designs were simulated and compared. The modeling results indicate that pressure loss in the vehicle's storage system is one of the main factors determining the mass flow and peak cooling requirements of the refueling process. The design of the refueling station does not influence the refueling of the vehicle when the requirements of the technical information report J2601 from Society of Automotive Engineers are met. However, by using multiple pressure stages in the tanks at the refueling station (instead of a single high-pressure tank), the total energy demand for cooling can be reduced by 12%, and the compressor power consumption can be reduced by 17%. The time between refueling is reduced by 5%, and the total amount of stored hydrogen at high pressure is reduced by 20%.     

Precooling temperature relaxation technology in hydrogen refueling for fuel-cell vehicles

The dissemination of fuel-cell vehicles requires cost reduction of hydrogen refueling stations. The temperature of the supplied hydrogen has currently been cooled to approximately −40 °C. This has led to larger equipment and increased electric power consumption. This study achieves a relaxation of the precooling temperature to the −20 °C level while maintaining the refueling time. (1) Adoption of an MC formula that can flexibly change the refueling rate according to the precooling temperature. (2) Measurement of thermal capacity of refueling system parts and re-evaluation. Selection from multiple refueling control maps according to the dispenser design (Mathison, et al., 2015). (3) Calculation of the effective thermal capacity and reselection of the map in real time when the line is cooled from refueling of the previous vehicle (Mathison, and Handa, 2015). (4) Addition of maps in which the minimum assumed pressures are 10 and 15 MPa. The new method is named MC Multi Map.     

A solar-powered,high-efficiency hydrogen fueling system using high-pressure electrolysis of water: Design and initial results

Hydrogen for fuel-cell electric vehicles (FCEVs) was produced using clean, renewable solar energy to electrolyze water. This report describes the design, construction, and initial performance testing of a solar hydrogen fueler at the GM Proving Ground in Milford, MI. The system used high-efficiency photovoltaic (PV) modules, a high-pressure (6500 psi, 44.8 MPa) electrolyzer, and an optimized direct connection between the PV and electrolyzer systems. This resulted in world-class solar to hydrogen efficiencies as high as 9.3% (based on H₂ lower heating value, LHV). The system could potentially supply approximately 0.5 kg of hydrogen per day from solar power for the average solar insolation in Detroit; more hydrogen would be produced in locations with more abundant sunshine. This is sufficient hydrogen to operate an FCEV for an average daily urban commute. Thus, the solar hydrogen fueler testing served as a “proof of concept” for clean, renewable hydrogen with potential applications including convenient, clean, quiet, small-scale home fueling of FCEVs (that can contribute to the growth of a future FCEV fleet) and fueling in remote locations where grid electricity is not available.     

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.     

Development and environmental impact of hydrogen supply chain in Japan: Assessment by the CGE-LCA method in Japan with a discussion of the importance of biohydrogen

Hydrogen is an attractive and clean source of energy with a high energy content and environmentally friendly production using green power. Hydrogen is therefore considered to be one of the future alternatives to fossil fuels that can limit the damage done by climate change. A dynamic GTAP model with LCA method is utilized herein in this investigation to forecast the development of the hydrogen supply chain and CO₂ emissions in Japan. The supply chain incorporates six hydrogen-related industries – biohydrogen, steam reforming, electrolysis, hydrogen fuel cell vehicles (HFCV), hydrogen fuel cells (HFC), and hydrogen fueling stations.     

Lessons learned from the installation and operation of Northern California's first 70-MPa hydrogen fueling station

A hydrogen dispensing facility capable of providing rapid 70-MPa vehicle fills became operational in May 2011 as the first such hydrogen dispensing facility in Northern California. The facility is operated by the University of California – Berkeley in support of fuel cell vehicle research with automakers, regional and state agencies, and industrial groups. In addition to storing and dispensing high-pressure hydrogen fuel, the station also incorporates a number of key advances in hydrogen refueling system capabilities, including novel fuel pre-cooling, fuel storage, and system safety systems. Key lessons learned from the construction and initial operation of the station include: 1) extensive initial planning is essential for smooth project development; 2) permitting is a key step and early engagement with local officials is critical; 3) extensive safety reviews may be required; 4) site work should be conducted with careful planning and execution; 5) methodical system commissioning is a key step in the project development process; 6) careful station maintenance and operational planning is critical for minimization of station downtime; and 7) station upkeep and utility expenses can be considerable.     

Numerical investigation of the vortex tube performance in novel precooling methods in the hydrogen fueling station

In the present study, the potential of integrating a Ranque-Hilsch vortex tube (RHVT) in the precooling process for refueling high-pressure hydrogen vehicles in hydrogen refueling stations is investigated. In this regard, two novel precooling processes integrating a vortex tube are proposed to significantly reduce the capital expenditure and operating costs in hydrogen fueling stations. Then a numerical study of the RHVT performance is carried out for a high-pressure hydrogen flow to validate the feasibility of the proposed processes. Obtained results from the numerical simulation show that the energy separation effect also exists in the RHVT with hydrogen flow at the pressure level of tens of megapascals. Moreover, it is found that the energy separation performance of the RHVT improves as the pressure ratio increases. In other words, the temperature drop of the cold exit of RHVT decreases as the pressure ratio decreases in the refueling process, which just matches the slowing-down temperature rise during the cylinder charge. Based on the obtained results, it is concluded that the integration of a RHVT into the precooling process has potential in the hydrogen fueling station.     

A comparison of test methods for the measurement of hydrogen sensor response and recovery times

Response time is a critically important property of hydrogen safety sensors. Recovery times are less important from a safety perspective, but are often quoted as an indication of the speed of operation of a sensor. However, the measured values depend highly on the method used to evaluate them. The purpose of this work is to assess the suitability of different methods, both flow and diffusion-based, for the measurement of sensor response and recovery times. Four methods have been tested in terms of their repeatability and practicality of execution, as well as the accuracy of their results compared to the manufacturer’s specifications. It was found that each method has its own advantages and limitations, which are discussed herein. For the measurement of response times, a diffusion-based method was found to give the shortest and most precise values and is therefore recommended. However, the flow-based method was found to be the most convenient experimentally and is the only method that is suitable for the measurement of recovery times over a wide concentration range.     

A numerical investigation on the efficiency of range extending systems using Advanced Vehicle Simulator

Series plug-in hybrid electric vehicles of varying engine configuration and battery capacity are modeled using Advanced Vehicle Simulator (ADVISOR). The performance of these vehicles is analyzed on the bases of energy consumption and greenhouse gas emissions on the tank-to-wheel and well-to-wheel paths. Both city and highway driving conditions are considered during the simulation. When simulated on the well-to-wheel path, it is shown that the range extender with a Wankel rotary engine consumes less energy and emits fewer greenhouse gases compared to the other systems with reciprocating engines during many driving cycles. The rotary engine has a higher power-to-weight ratio and lower noise, vibration and harshness compared to conventional reciprocating engines, although performs less efficiently. The benefits of a Wankel engine make it an attractive option for use as a range extender in a plug-in hybrid electric vehicle.     

Molecular dynamic simulation of aluminum-water reactions using the ReaxFF reactive force field

In this study we employed the ReaxFF reactive force field to examine the dynamics associated with the dissociation of adsorbed water molecules on an aluminum nanocluster surface. We have investigated several different concentrations of water on an Al₁₀₀ cluster to elucidate the dynamics of the dissociation phenomena. Our results indicate that the dissociation of an isolated water molecule on the surface requires significant activation energy, and that an assisted dissociation by a neighboring, non-adsorbed, water molecule is more energetically favorable. The dynamics of this reaction pathway are discussed and compared to recent quantum studies along with a further investigation of the role inert gases and oxide layers have on these processes. Our results shed light on this atomic scale behavior and increase the potential for reactive metal/water systems to be used as lightweight, portable, and on-demand energy sources via fast hydrogen gas production.     

Evaluation of hydrogen production methods using the Analytic Hierarchy Process

In this paper, seven common hydrogen production processes are evaluated using the Analytic Hierarchy Process (AHP) in respect to five criteria. The processes to be evaluated are steam methane reforming (SMR), partial oxidation of hydrocarbons (POX), coal gasification (CG), biomass gasification (BG), the combination of photovoltaics and electrolysis (PV–EL), the combination of wind power and electrolysis (W–EL) and the combination of hydropower and electrolysis (H–EL). The selected criteria that were used in the evaluation, for each of the seven hydrogen production processes are CO₂ emissions, operation and maintenance costs, capital cost, feedstock cost and hydrogen production cost. According to the evaluation, the processes that combine renewable energy sources with electrolysis (PV–EL, W–EL and H–EL) rank higher in classification than conventional processes (SMR, POX, CG and BG).     

Performance improvement of centrifugal compressors for fuel cell vehicles using the aerodynamic optimization and data mining methods

Centrifugal compressors are one of the most important auxiliary components in polymer electrolyte membrane fuel cell vehicles, which tend to operate at a narrow area with low specific speed. Here, the optimal design goals of centrifugal compressors are investigated on the basis of a lumped model for fuel cell systems. A three-dimensional multi-objective and multi-point aerodynamic optimization and data mining method for centrifugal compressors named ODM is presented via integrating a multi-island genetic algorithm, Reynolds-Average Navier-Stokes solver technique and self-organization map based data mining technique. Data mining indicates that compressor geometry would move to a small inlet diameter ratio and a narrow region of the outlet width ratio. Based on the optimization results, a centrifugal compressor for 100 kW fuel cell stack is manufactured. The experimental results show that the improvement of isentropic efficiency near low mass flow has been achieved, which indicates that the proposed ODM is effective in the performance improvement of centrifugal compressors for fuel cell vehicles.     

On dynamic operation modes of fuel cell: A comparison between the single-loop and multi-loop controls

Solid Oxide Fuel Cell (SOFC) is a promising alternative in power generation due to its reliable, efficient, and pollution free characteristics. However, the existing operation modes proposed for the SOFC dynamic control remain inconsistent and even conflicting. To this end, this paper compares the existing control schemes, detailing the merits and deficiencies, respectively. The dynamic model of a tubular SOFC is developed by formulating the disturbance input as load resistance instead of the load current, because the load current is coupled with the voltage during the transient. Different operation modes, i.e., constant fuel flow, constant fuel utilization, and constant voltage operation, are respectively investigated under load fluctuation. Simulation results show that constant fuel flow is advantageous in terms of simplicity; constant fuel utilization is superior in terms of efficiency; constant voltage operation will ease the necessity of using a converter. Finally, based on the nonlinearity, pairing, and coupling analyses, a multivariable operation strategy is explored to maintain fuel utilization and terminal voltage, simultaneously. The results show that this proposed operation strategy is able to achieve the merits of both the constant fuel utilization and constant voltage operation.     

Investigation of the interaction between hydrogen and irradiation defects in titanium by using positron annihilation spectroscopy

The formation of mono-vacancy, vacancy clusters and hydrogen-vacancy complexes with 30 keV H ion-irradiated pure titanium at different doses and temperatures was measured using by Positron annihilation spectroscopy (PAS). Results show a large number of H_mV_n clusters and vacancy-like defects in the samples irradiated at for room temperature, and that the formation of H_mV_n (m > n) at the sample irradiated at a high dose inhibits the increase of the S parameter. At increased irradiation temperature, the shrinkage of vacancy clusters and the effective open volume of defects decrease the S parameters. The high-temperature irradiation results in decreased vacancy-type defect concentration, and some hydrogen atoms diffuse from the cascade region to the track region, forming a large number of hydrogen-vacancy complexes in the track region. The coincidence Doppler broadening spectroscopy, an element analysis method, used to detect hydrogen in the ion-irradiated pure titanium sample, and results show hydrogen-related peaks in the high-momentum region, which may be due to the information of positron annihilation in the covalent bond formed by the H and the Ti elements. The increased radiation dose and temperature contribute to the formation of the hydrogen vacancy-complex, and the positron annihilation in high-momentum regions easily obtain hydrogen-related information.     

Exploring the relationship between the physical properties of activated carbon catalysts and their efficiency in catalyzing hydrogen iodide decomposition to produce hydrogen

Using simple and efficient methods to synthesize biological activated carbon catalysts (ACCs) with the decomposition of hydrogen iodide (HI) in the sulfur-iodine cycle as a typical reaction is urgently needed for the commercialization of hydrogen energy production and development. In this study, a series of ACCs with different specific surface areas (SSAs) and pore structures are prepared by comparing and controlling the changes in carbonization and activation methods of activated carbon (AC) preparation process. Hierarchical porous AC with larger SSA has higher HI decomposition efficiency. The representative samples H240H1h and H240C4h are hierarchical porous ACCs with 48.96% and 46.88% micropores, respectively, and have the highest catalytic activity in the entire series. The nitrogen adsorption and desorption curve is combined with pore size distribution data and analyzed using the capillary aggregation (Kelvin) and monolayer adsorption (Langmuir) theories. And ACC pore grading coefficient—which can improve data visualization—is introduced.     

The potential of hydrogen production from high and low-temperature electrolysis methods using solar and nuclear energy sources: the transition to a hydrogen economy in Brazil

Brazil has great potential for diversification and decarbonization of its energy matrix, with the insertion of a clean and renewable energy source such as hydrogen. This paper seeks to evaluate the surplus energy potential of solar and nuclear plants installed in the country for the production of green and purple hydrogen using high and low temperature electrolysis methods. Based on official reports and databases of energy production and demand, the results indicated that the total potential of surplus solar energy is equal to 4.29E+07 (kWh.d^?1). Further, the total potential of electricity production from the hydrogen obtained through surplus solar energy was equivalent to1.87E+07 (kWh.d^?1); and the total cost of producing solar hydrogen is equal to 1.07E+03 (USD.kWh^?1). In conclusion, the study contributed to demonstrate the pathways to the establishment of strategies that assist the transition to a hydrogen economy in Brazil.     

Assessment of the energy utilization efficiency in the Turkish transportation sector between 2000 and 2020 using energy and exergy analysis method

Energy and exergy utilization efficiencies in the Turkish transportation sector over the period from 2000 to 2020 are evaluated in this study. A comparison of the overall energy and exergy efficiencies of the Turkish transportation sector with the other countries is also presented. Energy and exergy analyses are performed for four transport modes, namely roadway, railway, airway and seaway, while they are based on the actual data for 2000 and projected data for 2020. Roadway appears to be the most efficient mode when compared with railway, air and seaway. It is projected that about 15% of total energy resources will be used in this sector during 2020. The energy utilization efficiencies for the Turkish transportation sector range from 23.71% in 2000 to 28.75% in 2020, while the exergy utilization efficiencies vary from 23.65% to 28.85% in the same years, respectively. Exergetic improvement potential for this sector is estimated to be 700 PJ in 2020, with an average increase rate of 4.5% annually between 2000 and 2020. Road transport and oil-fuelled combustion engines offer the principal scope for exergetic improvement in the coming decades. It may be concluded that the methodology used in this study is practical and useful for analyzing sectoral energy and exergy utilization to determine how efficiently energy and exergy are used in the sector studied. It is also expected that this study will be helpful in developing highly applicable and productive planning for energy policies.