An energy matching method for battery electric vehicle and hydrogen fuel cell vehicle based on source energy consumption rate

The smart cities development requires reducing energy consumption and using as much renewable energy as possible, so the widespread use of new energy vehicles is a very important measure. In this work, for the energy system configuration and energy efficiency balance of new energy vehicles, we propose an energy matching method to study its energy efficiency from the view point for energy life cycle. Nowadays, new energy vehicles mainly include battery electric vehicles (BEV) and hydrogen fuel cell vehicles (HFCEV). Firstly, we proposed the Source to Range (STR) model. Then, based on STR model, we used energy efficiency analysis chart to visually represent the conversion, delivery and consumption of the vehicle energy life cycle. Furthermore, we proposed a Source Energy Consumption Rate (SECR), which is used to evaluate the vehicles energy efficiency. Finally, based on STR model, we obtained the dividing line of the same SECR for new energy vehicles and equivalent fuel vehicles, which provides constraints on the vehicle energy system design. The results show that STR model can provide an effective tool for energy matching and energy efficiency analysis of new energy vehicles, and has a reference for product development of new energy vehicles.     

Analysis of the control strategies for fuel saving in the hydrogen fuel cell vehicles

A hydrogen fuel cell vehicle requires fuel cells, batteries, supercapacitors, controllers and smart control units with their control strategies. The controller ensures that a control strategy predicated on the data taken from the traction motor and energy storage systems is created. The smart control unit compares the fuel cell nominal output power with the vehicle power demand, calculates the parameters and continually adjusts the variables. The control strategies that can be developed for these units will enable us to overcome the technological challenges for hydrogen fuel cell vehicles in the near future. This study presents the best hydrogen fuel cell vehicle configurations and control strategies for safe, low cost and high efficiency by comparing control strategies in the literature for fuel economy.     

Economic energy management strategy design and simulation for a dual-stack fuel cell electric vehicle

This paper presents the design and simulation validation of two energy management strategies for dual-stack fuel cell electric vehicles. With growing concerns about environmental issues and the fossil energy crisis, finding alternative methods for vehicle propulsion is necessary. Proton exchange membrane (PEM) fuel cell systems are now considered to be one of the most promising alternative energy sources. In this work, the challenge of further improving the fuel economy and extending the driving range of a fuel cell vehicle is addressed by a dual-stack fuel cell system with specific energy management strategies. An efficiency optimization strategy and an instantaneous optimization strategy are proposed. Simulation validation for each strategy is conducted based on a dual-stack fuel cell electric vehicle model which follows the new European driving cycle (NEDC). Simulation results show that a dual-stack fuel cell system with proposed energy management strategies can significantly improve the fuel economy of a fuel cell vehicle and thus lengthen the driving range while being able to keep the start-stop frequency of the fuel cell stack within a reasonable range.     

Realistic simulation of fuel economy and life cycle metrics for hydrogen fuel cell vehicles

The present work contributes an engineered life cycle assessment (LCA) of hydrogen fuel cell passenger vehicles based on a real‐world driving cycle for semi‐urban driving conditions. A new customized LCA tool is developed for the comparison of conventional gasoline and hydrogen fuel cell vehicles (FCVs), which utilizes a dynamic vehicle simulation approach to calculate realistic, fundamental science based fuel economy data from actual drive cycles, vehicle specifications, road grade, engine performance, fuel cell degradation effects, and regenerative braking. The total greenhouse gas (GHG) emission and life cycle cost of the vehicles are compared for the case of hydrogen production by electrolysis in British Columbia, Canada. A 72% reduction in total GHG emission is obtained for switching from gasoline vehicles to FCVs. While fuel cell performance degradation causes 7% and 3% increases in lifetime fuel consumption and GHG emission, respectively, regenerative braking improves the fuel economy by 23% and reduces the total GHG emission by 10%. The cost assessment results indicate that the current FCV technology is approximately $2,100 more costly than the equivalent gasoline vehicle based on the total lifetime cost including purchase and fuel cost. However, prospective enhancements in fuel cell durability could potentially reduce the FCV lifetime cost below that of gasoline vehicles. Overall, the present results indicate that fuel cell vehicles are becoming both technologically and economically viable compared with incumbent vehicles, and provide a realistic option for deep reductions in emissions from transportation. Copyright © 2016 John Wiley & Sons, Ltd.     

Comparison of well-to-wheels energy use and emissions of a hydrogen fuel cell electric vehicle relative to a conventional gasoline-powered internal combustion engine vehicle

The operation of hydrogen fuel cell electric vehicles (HFCEVs) is more efficient than that of gasoline conventional internal combustion engine vehicles (ICEVs), and produces zero tailpipe pollutant emissions. However, the production, transportation, and refueling of hydrogen are more energy- and emissions-intensive compared to gasoline. A well-to-wheels (WTW) energy use and emissions analysis was conducted to compare a HFCEV (Toyota Mirai) with a gasoline conventional ICEV (Mazda 3). Two sets of specific fuel consumption data were used for each vehicle: (1) fuel consumption derived from the U.S. Environmental Protection Agency's (EPA's) window-sticker fuel economy figure, and (2) weight-averaged fuel consumption based on physical vehicle testing with a chassis dynamometer on EPA's five standard driving cycles. The WTW results show that a HFCEV, even fueled by hydrogen from a fossil-based production pathway (via steam methane reforming of natural gas), uses 5%–33% less WTW fossil energy and has 15%–45% lower WTW greenhouse gas emissions compared to a gasoline conventional ICEV. The WTW results are sensitive to the source of electricity used for hydrogen compression or liquefaction.     

Optimization of fuel cell system operating conditions for fuel cell vehicles

Proton exchange membrane fuel cell (PEMFC) technology for use in fuel cell vehicles and other applications has been intensively developed in recent decades. Besides the fuel cell stack, air and fuel control and thermal and water management are major challenges in the development of the fuel cell for vehicle applications. The air supply system can have a major impact on overall system efficiency. In this paper a fuel cell system model for optimizing system operating conditions was developed which includes the transient dynamics of the air system with varying back pressure. Compared to the conventional fixed back pressure operation, the optimal operation discussed in this paper can achieve higher system efficiency over the full load range. Finally, the model is applied as part of a dynamic forward-looking vehicle model of a load-following direct hydrogen fuel cell vehicle to explore the energy economy optimization potential of fuel cell vehicles.     

Efficiencies of hydrogen storage systems onboard fuel cell vehicles

Energy efficiency, vehicle weight, driving range, and fuel economy are compared among fuel cell vehicles (FCV) with different types of fuel storage and battery-powered electric vehicles. Three options for onboard fuel storage are examined and compared in order to evaluate the most energy efficient option of storing fuel in fuel cell vehicles: compressed hydrogen gas storage, metal hydride storage, and onboard reformer of methanol. Solar energy is considered the primary source for fair comparison of efficiencies for true zero emission vehicles. Component efficiencies are from the literature. The battery powered electric vehicle has the highest efficiency of conversion from solar energy for a driving range of 300 miles. Among the fuel cell vehicles, the most efficient is the vehicle with onboard compressed hydrogen storage. The compressed gas FCV is also the leader in four other categories: vehicle weight for a given range, driving range for a given weight, efficiency starting with fossil fuels, and miles per gallon equivalent (about equal to a hybrid electric) on urban and highway driving cycles.     

The effects of driving patterns and PEM fuel cell degradation on the lifecycle assessment of hydrogen fuel cell vehicles

This research paper mainly deals with the realistic simulation of hydrogen fuel cell vehicles and the development of a lifecycle assessment (LCA) tool to calculate and compare the environmental impacts of hydrogen fuel cell passenger vehicles with conventional vehicles. Since fuel cell vehicles are equipped with regenerative braking, they have strong potential to recover an ample portion of the energy being wasted in the braking system. Thus, the driving cycle can significantly affect the performance of fuel cell vehicles. In order to investigate the effect of driving patterns, several driving patterns are considered, and both vehicle fuel economy and lifecycle emissions are calculated and compared. Fuel cell degradation, on the other hand, is another major problem fuel cell vehicles face. This is mainly caused by the starts/stops, acceleration/deceleration, membrane humidity variation and a high load of the engine. When the vehicle operates on various driving patterns, the fuel cell will degrade which eventually affects the fuel economy. The effect of fuel cell degradation is also investigated for these driving patterns, and the results are compared. The results showed that the highway driving cycle has the lowest total lifecycle emission compared to New York city driving cycle, the city of Surrey (CoS) driving cycle, and the UDDS driving cycles. The results also indicate that fuel cell degradation undesirably affected the average fuel economy of the vehicle for about 23%.     

A preliminary life cycle assessment of PEM fuel cell powered automobiles

This paper provides a preliminary life cycle assessment (LCA) of polymer electrolyte membrane (PEM) fuel cell powered automobile. Life cycle of PEM fuel cell automobile not only includes operation of the vehicle on the road but also include production and distribution of both the vehicle and the fuel (e.g. hydrogen) during the vehicle’s entire lifetime. Assessment is based on the published data available in the literature. The two characteristics of the life cycle, which were assessed, are energy consumption and greenhouse gases (GHGs) emissions. Greenhouse gases (GHGs) emissions considered in the present assessment are CO₂ and CH₄. In addition, conventional internal combustion engine (ICE) automobile is also assessed based on similar characteristics for comparison with PEM fuel cell automobile. It is found that the energy utilized to generate the hydrogen during fuel cycle for the PEM automobile is about 3.5 times higher than the energy utilized to generate the gasoline during its fuel cycle. However, the overall life cycle energy consumption of PEM fuel cell automobile is about 2.3 times less than that of ICE automobile. Similarly, the GHGs emissions of PEMFC automobile are about 8.5 times higher than ICE automobile during the fuel cycle, but the overall life cycle GHGs emissions are about 2.6 times lower than ICE automobile.     

A robust online energy management strategy for fuel cell/battery hybrid electric vehicles

Traditional optimization-based energy management strategies (EMSs) do not consider the uncertainty of driving cycle induced by the change of traffic conditions, this paper proposes a robust online EMS (ROEMS) for fuel cell hybrid electric vehicles (FCHEV) to handle the uncertain driving cycles. The energy consumption model of the FCHEV is built by considering the power loss of fuel cell, battery, electric motor, and brake. An offline linear programming-based method is proposed to produce the benchmark solution. The ROEMS instantaneously minimizes the equivalent power of fuel cell and battery, where an equivalent efficiency of battery is defined as the efficiency of hydrogen energy transforming to battery energy. To control the state of charge of battery, two control coefficients are introduced to adjust the power of battery in objective function. Another penalty coefficient is used to amend the power of fuel cell, which reduces the load change of fuel cell so as to slow the degradation of fuel cell. The simulation results indicate that ROEMS has good performance in both fuel economy and load change control of fuel cell. The most important advantage of ROEMS is its robustness and adaptivity, because it almost produces the optimal solution without changing the control parameters when driving cycles are changed.     

Comparison among various energy management strategies for reducing hydrogen consumption in a hybrid fuel cell/supercapacitor/battery system

The aim of this study is to introduce a comprehensive comparison of various energy management strategies of fuel cell/supercapacitor/battery storage systems. These strategies are utilized to manage the energy demand response of hybrid systems, in an optimal way, under highly fluctuating load condition. Two novel strategies based on salp swarm algorithm (SSA) and mine-blast optimization are proposed. The outcomes of these strategies are compared with commonly used strategies like fuzzy logic control, classical proportional integral control, the state machine, equivalent fuel consumption minimization, maximization, external energy maximization, and equivalent consumption minimization. Hydrogen fuel economy and overall efficiency are used for the comparison of these different strategies. Results demonstrate that the proposed SSA management strategy performed best compared with all other used strategies in terms of hydrogen fuel economy and overall efficiency. The minimum consumed hydrogen and maximum efficiency are found 19.4 gm and 85.61%, respectively.     

Dynamic simulation and lifecycle assessment of hydrogen fuel cell electric vehicles considering various hydrogen production methods

In this research study, a real model of a hydrogen fuel cell vehicle is simulated using Simcenter Amesim software. The software used for vehicle simulation enabled dynamic simulation, resulting in more precise simulation. Furthermore, considering that fuel cell degradation is one of the significant challenges confronting fuel cell vehicle manufacturers, we examined the impact of fuel cell degradation on the performance of hydrogen vehicles. According to the findings, a hydrogen vehicle with a degraded fuel cell consumes 14.3% more fuel than a fresh fuel cell hydrogen vehicle. A comprehensive life cycle assessment (LCA) is also performed for the designed hydrogen vehicle. The results of the hydrogen vehicle life cycle assessment are compared with a gasoline vehicle to fully understand the effect of hydrogen vehicles in reducing air emissions. The methods considered for hydrogen production included natural gas reforming, electrolysis, and thermochemical water splitting method. Furthermore, because the source of electricity used for electrolysis has a significant impact on the life cycle emission of a hydrogen vehicle, three different power sources were considered in this assessment. Finally, while a hydrogen vehicle with a degraded fuel cell emits lower carbon dioxide (CO₂) than a gasoline vehicle, the emitted CO₂ from this vehicle using hydrogen from electrolysis is approximately 25% higher than that of a new hydrogen vehicle.     

Optimal energy management strategy of fuel-cell battery hybrid electric mining truck to achieve minimum lifecycle operation costs

Proton exchange membrane fuel cell (PEMFC) electric vehicle is an effective solution for improving fuel efficiency and onboard emissions, taking advantage of the high energy density and short refuelling time. However, the higher cost and short life of the PEMFC system and battery in an electric vehicle prohibit the fuel cell electric vehicle (FCEV) from becoming the mainstream transportation solution. The fuel efficiency-oriented energy management strategy (EMS) cannot guarantee the improvement of total operating costs. This paper proposes an EMS to minimize the overall operation costs of FCEVs, including the cost of hydrogen fuel, as well as the cost associated with the degradations of the PEMFC system and battery energy storage system (ESS). Based on the PEMFC and battery performance degradation models, their remaining useful life (RUL) models are introduced. The control parameters of the EMS are then optimized using a meta-model based global optimization algorithm. This study presents a new optimal control method for a large mining truck operating on a real closed-road operation cycle, using the combined energy efficiency and performance degradation cost measures of the PEMFC system and lithium-ion battery ESS. Simulation results showed that the proposed EMS could improve the total operating costs and the life of the FCEV.     

Dynamic behaviour of Li batteries in hydrogen fuel cell power trains

A Li ion polymer battery pack for road vehicles (48 V, 20 Ah) was tested by charging/discharging tests at different current values, in order to evaluate its performance in comparison with a conventional Pb acid battery pack. The comparative analysis was also performed integrating the two storage systems in a hydrogen fuel cell power train for moped applications. The propulsion system comprised a fuel cell generator based on a 2.5 kW polymeric electrolyte membrane (PEM) stack, fuelled with compressed hydrogen, an electric drive of 1.8 kW as nominal power, of the same typology of that installed on commercial electric scooters (brushless electric machine and controlled bidirectional inverter). The power train was characterized making use of a test bench able to simulate the vehicle behaviour and road characteristics on driving cycles with different acceleration/deceleration rates and lengths. The power flows between fuel cell system, electric energy storage system and electric drive during the different cycles were analyzed, evidencing the effect of high battery currents on the vehicle driving range. The use of Li batteries in the fuel cell power train, adopting a range extender configuration, determined a hydrogen consumption lower than the correspondent Pb battery/fuel cell hybrid vehicle, with a major flexibility in the power management.     

Variable structure battery-based fuel cell hybrid power system and its incremental fuzzy logic energy management strategy

A hybrid power system consists of a fuel cell and an energy storage device like a battery and/or a supercapacitor possessing high energy and power density that beneficially drives electric vehicle motor. The structures of the fuel cell-based power system are complicated and costly, and in energy management strategies (EMSs), the fuel cell's characteristics are usually neglected. In this study, a variable structure battery (VSB) scheme is proposed to enhance the hybrid power system, and an incremental fuzzy logic method is developed by considering the efficiency and power change rate of fuel cell to balance the power system load. The principle of VSB is firstly introduced and validated by discharge and charge experiments. Subsequently, parameters matching of the fuel cell hybrid power system according to the proposed VSB are designed and modeled. To protect the fuel cell as well as ensure the efficiency, a fuzzy logic EMS is formulated via setting the fuel cell operating in a high efficiency and generating an incremental power output within the affordable power slope. The comparison between a traditional deterministic rules-based EMS and the designed fuzzy logic was implemented by numerical simulation in three different operation conditions: NEDC, UDDS, and user-defined driving cycle. The results indicated that the incremental fuzzy logic EMS smoothed the fuel cell power and kept the high efficiency. The proposed VSB and incremental fuzzy logic EMS may have a potential application in fuel cell vehicles.     

Fuel economy and life-cycle cost analysis of a fuel cell hybrid vehicle

The most promising vehicle engine that can overcome the problem of present internal combustion is the hydrogen fuel cell. Fuel cells are devices that change chemical energy directly into electrical energy without combustion. Pure fuel cell vehicles and fuel cell hybrid vehicles (i.e. a combination of fuel cell and battery) as energy sources are studied. Considerations of efficiency, fuel economy, and the characteristics of power output in hybridization of fuel cell vehicle are necessary. In the case of Federal Urban Driving Schedule (FUDS) cycle simulation, hybridization is more efficient than a pure fuel cell vehicle. The reason is that it is possible to capture regenerative braking energy and to operate the fuel cell system within a more efficient range by using battery.Life-cycle cost is largely affected by the fuel cell size, fuel cell cost, and hydrogen cost. When the cost of fuel cell is high, hybridization is profitable, but when the cost of fuel cell is less than 400 US$/kW, a pure fuel cell vehicle is more profitable.     

Adaptive supervisory control strategy of a fuel cell/battery-powered city bus

This paper presents an adaptive supervisory control strategy for a fuel cell/battery-powered city bus to fulfill the complex road conditions in Beijing bus routes. An equivalent consumption minimization strategy (ECMS) is firstly proposed to optimize the fuel economy. The adaptive supervisory control strategy is exploited based on this, incorporating an estimating algorithm for the vehicle accessorial power, an algorithm for the battery charge-sustaining and a Recursive Least Squares (RLS) algorithm for fuel cell performance identification. Finally, an adaptive supervisory controller (ASC) considering the fuel consumption minimization, the battery charge-sustaining and the fuel cell durability has been implemented within the hybrid city buses. Results in the “China city bus typical cycle” testing and the demonstrational program of Beijing bus routes are presented, demonstrating that this approach provides an improvement of fuel economy along with robustness and ease of implementation. However, the fuel cell system does not leave much room for the optimal strategy to promote the fuel economy. Benefits may also result in a prolongation of the fuel cell working life, which needs to be verified in future.     

Cost-optimal design and energy management of fuel cell electric trucks

Road freight transport on hilly routes represents a significant challenge for the advancement of fuel cell electric trucks because of the high-performance requirements for fuel consumption, vehicle lifetime, and battery charge control. Therefore, it is essential to optimize the vehicle design and energy management, which greatly influence the driving performance and total cost of ownership. This paper focuses on the cost-optimal design and energy management of fuel cell electric trucks, considering five key influencing factors: powertrain component sizing, driving cycle, vehicle weight, component degradation, and market prices. The cost optimization relies on a novel predictive energy management scheme based on dynamic programming and the systematic calibration of control parameters. The paper analyzes the simulation results to highlight three main findings for fuel cell electric trucks: 1) cost-optimal energy management is essential to define the best trade-off between fuel consumption and component degradation; 2) the total cost of ownership is significantly influenced by component sizing, driving cycles, vehicle weight, and market prices; 3) predictive energy management is highly beneficial in challenging road topographies for substantial cost-saving and lower component size requirements.     

Abating transport GHG emissions by hydrogen fuel cell vehicles: Chances for the developing world

Fuel cell vehicles, as the most promising clean vehicle technology for the future, represent the major chances for the developing world to avoid high-carbon lock-in in the transportation sector. In this paper, by taking China as an example, the unique advantages for China to deploy fuel cell vehicles are reviewed. Subsequently, this paper analyzes the greenhouse gas (GHG) emissions from 19 fuel cell vehicle utilization pathways by using the life cycle assessment approach. The results show that with the current grid mix in China, hydrogen from water electrolysis has the highest GHG emissions, at 3.10 kgCO₂/km, while by-product hydrogen from the chlor-alkali industry has the lowest level, at 0.08 kgCO₂/km. Regarding hydrogen storage and transportation, a combination of gas-hydrogen road transportation and single compression in the refueling station has the lowest GHG emissions. Regarding vehicle operation, GHG emissions from indirect methanol fuel cell are proved to be lower than those from direct hydrogen fuel cells. It is recommended that although fuel cell vehicles are promising for the developing world in reducing GHG emissions, the vehicle technology and hydrogen production issues should be well addressed to ensure the life-cycle low-carbon performance.     

Performance optimization of hybrid hydrogen fuel cell-electric vehicles in real driving cycles

In this research study, a fuel cell-electric hybrid car is studied. This car includes an electric motor that is connected to a fuel cell and a complex which includes a battery pack and an Ultracapacitor. The assessment of this hybrid vehicle is conducted by using various driving cycles such as FTP-75 driving cycle, NEDC driving cycle and SFTP-SC03 driving cycle. Battery state of charge (SoC) and hydrogen fuel consumption are the effective parameters influencing the vehicle performance. For analysing the performance of this vehicle, an innovative computational model is considered. In this innovative computational model, an accurate control strategy is considered in order to control the power demand, staying the battery packs and the Ultracapacitor state of charge in a limited domain. Results show that in NEDC driving cycle, by means of using Ultracapacitor in this model, 3.3% reduction in fuel consumption and 20.2% decrease in the difference between initial and final State of Charge (SoC) in battery pack can be achieved. In addition, a robust regenerative braking control strategy is used in order to recover some parts of the wasted energy in braking driving modes.