An overview: Current progress on hydrogen fuel cell vehicles

The harmful consequences of pollutants emitted by conventional fuel cars have prompted vehicle manufacturers to shift towards alternative energy sources. Currently, fuel cells (FCs) are commonly regarded as highly efficient and non-polluting power sources capable of delivering far greater energy densities and energy efficiency than conventional technologies. Proton exchange membrane fuel cells (PEMFC) are viewed as promising in transportation sectors because of their ability to start at cold temperatures and minimal emissions. PEMFC is an electrochemical device that converts hydrogen and oxidants into electricity, water, and heat at various temperatures. The pros and cons of the technology are discussed in this article. Various fuel cell types and their applications in the portable, automobile, and stationary sectors are discussed. Additionally, recent issues associated with existing fuel cell technology in the automobile sector are reviewed.     

Fuel cell-battery hybrid powered light electric vehicle (golf cart): Influence of fuel cell on the driving performance

A light electric vehicle (golf cart, 5 kW nominal motor power) was integrated with a commercial 1.2 kW PEM fuel cell system, and fuelled by compressed hydrogen (two composite cylinders, 6.8 L/300 bar each). Comparative driving tests in the battery and hybrid (battery + fuel cell) powering modes were performed. The introduction of the fuel cell was shown to result in extending the driving range by 63–110%, when the amount of the stored H₂ fuel varied within 55–100% of the maximum capacity. The operation in the hybrid mode resulted in more stable driving performances, as well as in the increase of the total energy both withdrawn by the vehicle and returned to the vehicle battery during the driving. Statistical analysis of the power patterns taken during the driving in the battery and hybrid-powering modes showed that the latter provided stable operation in a wider power range, including higher frequency and higher average values of the peak power.     

Investigation and analysis of proton exchange membrane fuel cell dynamic response characteristics on hydrogen consumption of fuel cell vehicle

The number of working points and response speed are two essential characteristics of proton exchange membrane fuel cell (PEMFC). The improper setting of the number of working points and response speed may reduce the life of PEMFC and increase the hydrogen consumption of the vehicle. This paper explores the impact of the response speed as well as the working points of the PEMFC on the hydrogen consumption in the real-system level. In this paper a dynamic model of the PEMFC system is established and verified by experiments. The model is able to reflect the dynamic response process of PEMFC under a series different number of working points and different response speed. Based on the proposed model, the influence of working points and the response speed of PEMFC on the hydrogen consumption in the vehicle under different driving cycles is analyzed and summarized, for the first time, in the open literature. The results highlight that the hydrogen consumption will decreases in both cases that with the increase of working point number and increase of response speed. However, the reduction range of hydrogen consumption trends to smaller and may reach to an optimal level considering the trade-off between the hydrogen saving and the other costs, for example the control cost. Also, with a more complex driving cycle, the working points and response speed have a greater the impact on the hydrogen consumption in the vehicle applications.     

The computer-aided analysis for the driving stability of a plug-in fuel cell vehicle using a proton exchange membrane fuel cell

In order to analyze the driving stability of a plug-in fuel cell vehicle (PFCV), a computer-aided simulator for PFCVs has been developed. PFCVs have been introduced around the world to achieve early commercialization of an eco-friendly and highly efficient fuel cell vehicle. The plug-in option, which allows the battery to be recharged from the electricity grid, enables a reduction in size of the fuel cell system (FCS) and an improvement of its durability. As such, the existing limitations of the fuel cell - such as its high cost, poor durability, and the insufficient hydrogen infrastructure – can be overcome. During the design phase of PFCV development, simulation-based driving stability test is necessary to determine the sizes of the electric engine of the FCS and the battery. The developed simulator is very useful for analyzing the driving stability of the PFCV with respect to the capacities of the FCS and battery. The simulation results are in fact very close to those obtained from a real system, since the estimation accuracy of PFCV component models used in this simulator, such as the fuel cell stack, battery, electric vehicle, and the other balance of plants (BOPs), are verified by the experiments, and the simulator uses the newly-proposed power distribution control logic and the pre-confirmed real driving schedule. Using these results, we can study which one will be the best in terms of driving stability.     

Experimental investigation on the dynamic performance of a hybrid PEM fuel cell/battery system for lightweight electric vehicle application

A hybrid system combining a 2 kW air-blowing proton exchange membrane fuel cell (PEMFC) stack and a lead–acid battery pack is developed for a lightweight cruising vehicle. The dynamic performances of this PEMFC system with and without the assistance of the batteries are systematically investigated in a series of laboratory and road tests. The stack current and voltage have timely dynamic responses to the load variations. Particularly, the current overshoot and voltage undershoot both happen during the step-up load tests. These phenomena are closely related to the charge double-layer effect and the mass transfer mechanisms such as the water and gas transport and distribution in the fuel cell. When the external load is beyond the range of the fuel cell system, the battery immediately participates in power output with a higher transient discharging current especially in the accelerating and climbing processes. The DC–DC converter exhibits a satisfying performance in adaptive modulation. It helps rectify the voltage output in a rigid manner and prevent the fuel cell system from being overloaded. The dynamic responses of other operating parameters such as the anodic operating pressure and the inlet and outlet temperatures are also investigated. The results show that such a hybrid system is able to dynamically satisfy the vehicular power demand.     

An online prognostics-based health management strategy for fuel cell hybrid electric vehicles

As the energy transformation in the transportation sector is taking place driven by the development of fuel cell technologies, fuel cell hybrid electric vehicles become promising solutions owing to their long driving duration and zero emissions. However, the unsatisfied lifespan of fuel cells is an inevitable obstacle for their massive commercialization. This paper aims to propose an online adaptive prognostics-based health management strategy for fuel cell hybrid electric vehicles, which can improve the durability of the fuel cell thanks to online health monitoring. Here, particle filtering method is adapted for online fuel cell prognostics and the uncertainty of the predicted results is calculated based on the distribution of particles. A health management strategy is developed based on prognostics and a decision-making process is designed by considering the prognostics uncertainty through a decision fusion method. The obtained results show that the developed strategy has effectively improved the durability of the on-board fuel cell by up to 95.4%. Moreover, a sensitivity analysis of the prognostics occurrence frequency and probability calculation has also been conducted in this paper.     

Multi-mode control strategy for fuel cell electric vehicles regarding fuel economy and durability

A proton electrolyte membrane (PEM) fuel cell system and a Li-ion battery (LIB) are two power sources in a fuel cell electric vehicle (FCEV). The fuel cell system is composed of a fuel cell stack and subsystems for air/hydrogen supply and cooling water. The operation procedure of the fuel cell system can be generally separated into several processes, e.g. starting up, normal/abnormal working and shutting down. In this paper, a multi-mode real-time control strategy for a FCEV is proposed. The strategy is established based on three typical processes (starting up, normal working, shutting down) of the fuel cell system, taking the fuel economy and system durability into consideration. The strategy is applied into a platform vehicle for the 12th 5-year project of “the next generation technologies of fuel cell city buses”. Experiments of the “China city bus typical cycle” on a test bench for the bus were carried out. Results show that, the fuel economy is 7.6 kg (100 km)⁻¹ in the battery charge-sustaining status. In a practical situation, a total driving mileage of more than 270 km can be achieved. Cycle testing also showed that, the degradation rate of the fuel cell was reduced to half of the original level. No performance degradation of the LIB system was observed in the cycling test.     

Performance degradation prediction of proton exchange membrane fuel cell using a hybrid prognostic approach

The proton exchange membrane fuel cell has been widely used for industrial systems; however, its performance gradually degrades during use. Therefore, the study on the performance degradation prediction of fuel cells is helpful to extend its lifespan. In this paper, a novel hybrid approach using a combination of model-based adaptive Kalman filter and data-driven NARX neural network is proposed to predict the degradation of fuel cells. The overall degradation trend (i.e., irreversible degradation process) is captured by an empirical aging model and adaptive Kalman filter. Meanwhile, the detail degradation information (i.e., reversible degradation process) is depicted by the NARX neural network. Moreover, the correlation analysis of the reversible voltage time series is carried out to obtain the number of delays of the NARX neural network based on the autocorrelation function and the partial autocorrelation function. Then, the total degradation prediction is the sum of the overall degradation prediction and the detail degradation prediction. Finally, the prognostic capability of the proposed method is verified by two aging datasets, and the results show the effectiveness and superiority of the proposed method which can provide accurate degradation forecasting and remaining useful life.     

Fuel economy evaluation of fuel cell hybrid vehicles based on equivalent fuel consumption

Fuel cell hybrid vehicles (FCHVs) have become a major topic of interest in the automotive industry owing to recent energy supply and environmental problems. Consequently, fuel economy evaluation methods of FCHVs have a popular research topic. The initial state of charge (SOC) and the final SOC of the battery have to be identical in an evaluation of the fuel economy of an FCHV. In an actual driving situation or during a forward simulation, however, the final SOC depends on the power management strategy, which is usually different from the initial SOC. To consider the effect of the difference between the initial and final SOC on fuel economy evaluation, the concept of equivalent fuel consumption, based on the optimal control, is introduced in this paper. A rule-based power management strategy is applied to an FCHV, and its fuel economy is evaluated in terms of the equivalent fuel consumption and compared to the optimal control result.     

Development of emergency response strategies for typical accidents of hydrogen fuel cell electric vehicles

First responders are facing new challenges in handling hydrogen vehicle accidents. Hazard analyses, physical effects evaluations, and accident progression studies are performed to develop appropriate emergency response strategies. Results show that hydrogen release from thermally-activated pressure relief device and catastrophic tank rupture are the two major accidents leading to large hazard zones. Three types of hazard distances and accident durations are determined by the novel nomograms built in the paper. The nomograms indicate that fireball radiation leads to longer hazard distances than overpressure effects in the event of catastrophic tank rupture. Based on the hydrogen physical effects evaluations and accident progression analyses, new emergency response strategies are developed to deal with the typical accidents of hydrogen vehicles, including traffic collision on a road, vehicle fire in a parking lot, and hydrogen leak during refueling at a station. Rapid initial assessment techniques, firefighting strategy, rescue operation tactics and waste disposal pre-treatment are proposed.     

Recent approaches to improve Nafion performance for fuel cell applications: A review

Among various polymeric materials applied as polymer electrolyte membrane (PEM) for fuel cells, Nafion is known as a standard polymer so that any new material needs to be compared with it. However, low proton conductivity under anhydrous conditions at elevated temperatures due to water evaporation and consequent need for water management, and its low tolerance for fuel impurities still remain as Nafion's major shortcomings. Development of new PEM with higher conductivity at high temperatures and stability for application at anhydrous conditions is highly desired. The aim of this review is thus to specify the latest achievements made to improve the Nafion performance by means of pretreatments, incorporation of reinforcing agents, nanocomposites, blending, ionic liquids, and so on. In recent years, a significant enhancement in Nafion performance, at humidified conditions, has been reported and many efforts have been conducted to improve its performance under dried conditions. Although impressive enhancements in Nafion performance have been reported, a need for revolutionary approaches to overcome its drawbacks is undeniably needed for future works.     

Overview of the next quarter century vision of hydrogen fuel cell electric vehicles

Last three decades, costumers and manufacturers of automotive sector have been influenced positively by Hydrogen and fuel cells (FCs). The main goal of automakers can be pointed as minimizing the fuel consumption and exhaust emissions while improving the range limits, energy efficiency and latest technology adaptation. Therewithal, electric assisted propulsion systems added to vehicles and are called as electric vehicles (EVs). For that matter, Battery Electric Vehicles (BEVs) and hydrogen Fuel Cell Electric Vehicles (FCEVs) have become the focus of researchers and producers. In this mini foreseen review, overview of the next quarter century vision of FCEVs are expressed and discussed by the helped of previous researches and with future forecast reports. The introduction part is summarized the general approach and future expectations of FCs in detailed. Technical overview is represented for FCs and FCEVs in terms of current state of technology to foreseen expectancy. Infrastructure analysis and future aspects overview part is also discussed for sector's perspective on FCEVs. The near future perspective of the FCEVs, which is seen as the next step in EVs, is discussed in detail in the next quarter century vision. Authors concluded that, between the 2030s-2050s, hydrogen FCEVs will continue their rising demand scale under the circumstances of decreasing expensive technology; enhanced energy optimization; extended range limits and increasing hydrogen refueling stations.     

Parametric analysis of the proton exchange membrane fuel cell performance using design of experiments

Proton exchange membrane fuel cell (PEMFC) performance depends on different fuel cell operating temperatures, humidification temperatures, operating pressures, flow rates, and various combinations of these parameters. This study employed the method of the design of experiments (DOE) to obtain the optimal combination of the six primary operating parameters (fuel cell operating temperatures, operating pressures, anode and cathode humidification temperatures, anode and cathode stoichiometric flow ratios). In the first stage, this study adopted a 2^k−2 fractional factorial design of the DOE to determine whether these factors have significant effects on a response and the interactions between various parameters. Second, the L₂₇(3¹³) orthogonal array of the Taguchi method is utilized to determine the optimal combination of factors for a fuel cell. Based on this study, the operating pressure, the operating temperature, and the interactions between operating temperature and operating pressure have a significant effect on the fuel cell performance. Among them, the operating pressure is the most important contributor. When the operating pressure increases, it should simultaneously lower the effects of other factors. While both the operating temperature and pressure increase simultaneously with that, the other factors are at appropriate conditions, it is possible to improve the fuel cell performance.     

Generation of high-pressure hydrogen for fuel cell electric vehicles using photovoltaic-powered water electrolysis

Increasing the utilization of electric drive systems including hybrid, battery, and fuel cell electric vehicles (FCEV) will reduce the usage of petroleum and the emission of air pollution by vehicles. The eventual production of electricity and hydrogen in a renewable fashion, such as using solar energy, can achieve the long-term vision of having no tailpipe emissions, as well as eliminating the dependence of the transportation sector on dwindling supplies of petroleum for its energy. Before FCEVs can be introduced in large numbers, a hydrogen-fueling infrastructure is needed. This report describes an early proof-of-concept for a distributed hydrogen fueling option in which renewably generated, high-pressure hydrogen is dispensed at an FCEV owner’s home. In an earlier report we described the design and initial characterization of a solar photovoltaic (PV) powered electrolyzer/storage/dispensing (ESD) system that was a proof-of-concept for a single FCEV home fueling system. In the present report we determined the efficiency and other operational characteristics of that PV-ESD system during testing over a 109-day period at the GM Proving Ground in Milford, MI, at a hydrogen output pressure of approximately 2000 psi (13.8 MPa). The high pressure was achieved without any mechanical compression via electrolysis. Over the study period the photovoltaic solar to electrical efficiency averaged 13.7%, the electrolyzer efficiency averaged 59%, and the system solar to hydrogen efficiency averaged 8.2% based on the hydrogen lower heating value. A well-documented model used to evaluate solar photovoltaic power systems was used to calculate the maximum power point values of the voltage, current, and power of our PV system in order to derive the coupling factor between the PV and ESD systems and to determine its behavior over the range of environmental conditions experienced during the study. The average coupling factor was near unity, indicating that the two systems remained coupled in an optimal fashion. Also, the system operated well over a wide range of meteorological conditions, and in particular it responded quickly to instantaneous changes in the solar irradiance (caused by clouds) with negligible effect on the overall efficiency. During the study up to 0.67 kg of high-pressure hydrogen was generated on a sunny day for fueling FCEV. Future generations of high-pressure electrolyzers, properly combined with solar PV systems, can offer a compact, efficient, and environmentally acceptable system for FCEV home fueling.     

Power generation using a mesoscale fuel cell integrated with a microscale fuel processor

An integrated fuel reformer and fuel cell system for microscale (10–500 mW) power generation is being developed and demonstrated as an alternative to conventional batteries. In this system, thermal energy is transformed to electricity by stripping the hydrogen from the hydrocarbon fuel (reforming) and converting the hydrogen to electricity in a proton exchange membrane (PEM) fuel cell. The fabrication and operation of a mesoscale fuel cell based on phosphoric acid doped polybenzimidazole (PBI) technology is discussed, along with tests integrating the methanol processor with the fuel cell. The PBI membrane had high ionic conductivity at high temperatures (>150 °C), and sustained the high conductivity at low relative humidity at these temperatures. This high-temperature stability and high ionic conductivity enabled the membrane to tolerate extremely high levels of carbon monoxide up to 10% without significant degradation in performance. The combined fuel cell/reformer system was successfully operated to enable the production of 23 mW of electrical power.     

Degradation prediction of proton exchange membrane fuel cell using auto-encoder based health indicator and long short-term memory network

As durability of proton exchange membrane fuel cell (PEMFC) remains as the main obstacle for its larger scale commercialization, predicting PEMFC degradation progress is thus an effective way to extend its lifetime. To realize reliable prediction, a novel health indicator (HI) extraction method based on auto-encoder is proposed in this paper, with which PEMFC future voltage can be predicted by long short-term memory network (LSTM). The effectiveness and robustness of proposed approach is investigated with test data simulating vehicle operation conditions, and accurate prediction performance can be observed, with the maximum root mean square error (RMSE) of 0.003513. Moreover, by comparing with two commonly prognostic methods including attention-based gated recurrent unit network and polarization model-LSTM, the proposed method can provide better predictions under various operating conditions. Furthermore, with the proposed method, the degradation mechanism of PEMFC can also be analyzed. Therefore, the proposed prognostic method can predict reliable PEMFC degradation progress and its corresponding degradation mechanisms, which will be beneficial in practical PEMFC systems for taking appropriate strategies to guarantee PEMFC durability.     

Review on health-conscious energy management strategies for fuel cell hybrid electric vehicles: Degradation models and strategies

Considering the overwhelming pressure on worldwide demand of fossil fuels and the climate change caused by air pollution, hybrid electric vehicles have seen a promising future thanks to the development of renewable energy sources. Among various kinds of energy sources that have been used in hybrid electric vehicles, lithium-ion battery and proton exchange membrane (PEM) fuel cell exist to be the most favorable ones owing to their high energy density and power density. However, the degradation issues of the energy sources tend to be neglected when designing the energy management strategies for the hybrid electric vehicles. Concerning existing literature, degradation modelling methods of lithium-ion batteries and PEM fuel cells are reviewed and the possibility of integrating them into health-conscious energy management is discussed. Besides, a variety of energy management strategies that have taken the influence of degradations into consideration are reviewed and classified. The contribution of this paper is to investigate the possibility of developing a health-conscious energy management strategy based on accurate estimation of degradation to improve the durability of the system.     

Proton exchange membrane fuel cell degradation prediction based on Adaptive Neuro-Fuzzy Inference Systems

This paper studies the prediction of the output voltage reduction caused by degradation during nominal operating condition of a PEM fuel cell stack. It proposes a methodology based on Adaptive Neuro-Fuzzy Inference Systems (ANFIS) which use as input the measures of the fuel cell output voltage during operation. The paper presents the architecture of the ANFIS and studies the selection of its parameters. As the output voltage cannot be represented as a periodical signal, the paper proposes to predict its temporal variation which is then used to construct the prediction of the output voltage. The paper also proposes to split this signal in two components: normal operation and external perturbations. The second component cannot be predicted and then it is not used to train the ANFIS. The performance of the prediction is evaluated on the output voltage of two fuel cells during a long term operation (1000 h). Validation results suggest that the proposed technique is well adapted to predict degradation in fuel cell systems.     

Life cycle cost of conventional,battery electric,and fuel cell electric vehicles considering traffic and environmental policies in China

Electric vehicles (EVs) are considered a promising alternative to conventional vehicles (CVs) to alleviate the oil crisis and reduce urban air pollution and carbon emissions. Consumers usually focus on the tangible cost when choosing an EV or CV but overlook the time cost for restricting purchase or driving and the environmental cost from gas emissions, falling to have a comprehensive understanding of the economic competitiveness of CVs and EVs. In this study, a life cycle cost model for vehicles is conducted to express traffic and environmental policies in monetary terms, which are called intangible cost and external cost, respectively. Battery electric vehicles (BEVs), fuel cell electric vehicles (FCEVs), and CVs are compared in four first-tier, four new first-tier, and 4 s-tier and below cities in China. The comparison shows that BEVs and FCEVs in most cities are incomparable with CVs in terms of tangible cost. However, the prominent traffic and environmental policies in first-tier cities, especially in Beijing and Shanghai, greatly increase the intangible and external costs of CVs, making consumers more inclined to purchase BEVs and FCEVs. The main policy benefits of BEVs and FCEVs come from three aspects: government subsidies, purchase and driving restrictions, and environmental taxes. With the predictable reduction in government subsidies, traffic and environmental policies present important factors influencing the competitiveness of BEVs and FCEVs. In first-tier cities, BEVs and FCEVs already have a competitive foundation for large-scale promotion. In new first-tier and second-tier and below cities, stricter traffic and environmental policies need to be formulated to offset the negative impact of the reduction in government subsidies on the competitiveness of BEVs and FCEVs. Additionally, a sensitivity analysis reveals that increasing the mileage and reducing fuel prices can significantly improve the competitiveness of BEVs and FCEVs, respectively.