Transportation options in a carbon-constrained world: Hybrids,plug-in hybrids,biofuels, fuel cell electric vehicles,and battery electric vehicles

Multiple alternative vehicle and fuel options are being proposed to alleviate the threats of climate change, urban air pollution, and oil dependence caused by the transportation sector. We report here on the results from an extensive computer model developed over the last decade to simulate and compare the societal benefits of deploying various alternative transportation options including hybrid electric vehicles and plug-in hybrids fueled by gasoline, diesel fuel, natural gas, and ethanol, and all-electric vehicles powered by either batteries or fuel cells. These simulations compare the societal benefits over a 100-year time horizon of each vehicle/fuel combination in terms of reduced local air pollution, greenhouse gas pollution, and oil consumption compared to gasoline cars.     

Impact of battery weight and charging patterns on the economic and environmental benefits of plug-in hybrid vehicles

Plug-in hybrid electric vehicle (PHEV) technology is receiving attention as an approach to reducing US dependency on foreign oil and greenhouse gas (GHG) emissions from the transportation sector. PHEVs require large batteries for energy storage, which affect vehicle cost, weight, and performance. We construct PHEV simulation models to account for the effects of additional batteries on fuel consumption, cost, and GHG emissions over a range of charging frequencies (distance traveled between charges). We find that when charged frequently, every 20 miles or less, using average US electricity, small-capacity PHEVs are less expensive and release fewer GHGs than hybrid electric vehicles (HEVs) or conventional vehicles. For moderate charging intervals of 20–100 miles, PHEVs release fewer GHGs, but HEVs have lower lifetime costs. High fuel prices, low-cost batteries, or high carbon taxes combined with low-carbon electricity generation would make small-capacity PHEVs cost competitive for a wide range of drivers. In contrast, increased battery specific energy or carbon taxes without decarbonization of the electricity grid would have limited impact. Large-capacity PHEVs sized for 40 or more miles of electric-only travel do not offer the lowest lifetime cost in any scenario, although they could minimize GHG emissions for some drivers and provide potential to shift air pollutant emissions away from population centers. The tradeoffs identified in this analysis can provide a space for vehicle manufacturers, policymakers, and the public to identify optimal decisions for PHEV design, policy and use. Given the alignment of economic, environmental, and national security objectives, policies aimed at putting PHEVs on the road will likely be most effective if they focus on adoption of small-capacity PHEVs by urban drivers who can charge frequently.     

The fuel cell electric vehicles: The highlight review

Transportation sector is the important sector and consumed the most fossil fuel in the world. Since COVID-19 started in 2019, this sector had become the world connector because every country relies on logistics. The transportation sector does not only deal with the human transportation but also relates to logistics. Research in every country has searched for alternative transportation to replace internal combustion engines using fossil fuel, one of the most prominent choices is fuel cells. Fuel cells can use hydrogen as fuel. Hydrogen can be fed to the fuel cells to provide electric power to drive vehicles, no greenhouse gas emission and no direct combustion required. The fuel cells have been developed widely as the 21st century energy-conservation devices for mobile, stationary, and especially vehicles. The fuel cell electric vehicles using hydrogen as fuel were also called hydrogen fuel cell vehicles or hydrogen electric vehicles. The fuel cells were misconceived by several people that they were batteries, but the fuel cells could provide electric power continuously if their fuel was provided continuously. The batteries could provide electric power as their only capacities, when all ions are released, no power could be provided. Because the fuel cell vehicles play important roles for our future transportation, the overall review for these vehicles is significantly interesting. This overall review can provide general and technical information, variety of readers; vehicle users, manufacturers, and scientists, can perceive and understand the fuel cell vehicles within this review. The readers can realize how important the fuel cell technologies are and support research around the world to drive the fuel cell vehicles to be the leading vehicles in our sustainable developing world.     

Analysis of plug-in hybrid electric vehicle utility factors

Plug-in hybrid electric vehicles (PHEVs) are hybrid electric vehicles that can be fueled from both conventional liquid fuels and grid electricity. To represent the total contribution of both of these fuels to the operation, energy use, and environmental impacts of PHEVs, researchers have developed the concept of the utility factor. As standardized in documents such as SAE J1711 and SAE J2841, the utility factor represents the proportion of vehicle distance travelled that can be allocated to a vehicle test condition so as to represent the real-world driving habits of a vehicle fleet. These standards must be used with care so that the results are understood within the context of the assumptions implicit in the standardized utility factors. This study analyzes and derives alternatives to the standard utility factors from the 2001 National Highway Transportation Survey, so as to understand the sensitivity of PHEV performance to assumptions regarding charging frequency, vehicle characteristics, driver characteristics, and means of defining the utility factor. Through analysis of these alternative utility factors, this study identifies areas where analysis, design, and policy development for PHEVs can be improved by alternative utility factor calculations.     

Fuel reduction and electricity consumption impact of different charging scenarios for plug-in hybrid electric vehicles

Plug-in hybrid electric vehicles (PHEVs) consume both gasoline and grid electricity. The corresponding temporal energy consumption and emission trends are valuable to investigate in order to fully understand the environmental benefits. The 24-h energy consumption and emission profile depends on different vehicle designs, driving, and charging scenarios. This study assesses the potential energy impact of PHEVs by considering different charging scenarios defined by different charging power levels, locations, and charging time. The region selected for the study is the South Coast Air Basin of California. Driving behaviors are derived from the National Household Travel Survey 2009 (NHTS 2009) and vehicle parameters are based on realistic assumptions consistent with projected vehicle deployments. Results show that the reduction in petroleum consumption is significant compared to standard gasoline vehicles and the ability to operate on electricity alone is crucial to cold start emission reduction. The benefit of higher power charging on petroleum consumption is small. Delayed and average charging are better than immediate charging for home, and non-home charging increases peak grid loads.     

Fuel cell vehicles: State of the art with economic and environmental concerns

Hydrogen fueled fuel cell vehicles (FCVs) will play a major role as a part of the change toward the hydrogen based energy system. When combined with the right source of energy, fuel cells have the highest potential efficiencies and lowest potential emissions of any vehicular power source. As a result, extensive work into the development of hydrogen fueled FCVs is taking place. The aim of this paper is to highlight some of the research and development work which has occurred in the past five years on fuel cell vehicle technology, with a focus on economic and environmental concerns. It is observed that the current efforts are divided up into several parts. The performance, durability, and cost of fuel cell technology continue to be improved, and some fuel cells are currently ready to be mounted on vehicles and tested. Environmental and economic assessments of the entire hydrogen supply chain, including fuel cell end-use, are being carried out by groups of researchers around the world. It is currently believed that fuel cells need at least five more years of testing and improvement before large scale commercialization can begin. Economic and environmental analyses show that FCVs will likely be both economically competitive and environmentally benign. Indeed, the transition of the transportation sector to the use of hydrogen FCVs will represent one of the biggest steps toward the hydrogen economy.     

“How green are electric vehicles?”

Battery electric vehicles (BEVs) and plug-in hybrid electric vehicles (PHEVs) are often labeled “green”, implying that they will significantly reduce greenhouse gas (GHG) emissions. But actual GHG reductions will depend on two factors: the number of electric vehicles that can be sold to Americans that are fond of driving large vehicles long distances, and the GHGs emitted by the electrical power plants that charge the EV batteries. This article evaluates the maximum potential of EVs to cut GHG emissions and oil consumption in the U.S. and compares them with the GHG and oil reduction potential of hydrogen-powered fuel cell electric vehicles. Even if all US light duty vehicles (LDVs) (cars and trucks) were replaced by a combination of battery EVs for small vehicles and plug-in hybrids for all other LDVs, then GHGs could at most be reduced by 25% and oil consumption could be reduced by less than 67%. But if all LDVs in the U.S. were replaced by fuel cell electric vehicles powered by hydrogen made from natural gas, then GHGs would be immediately reduced by 44% and oil consumption by nearly 100%.     

US marginal electricity grid mixes and EV greenhouse gas emissions

Battery electric vehicles (BEVs) are often portrayed as “green,” implying negligible greenhouse gas (GHG) emissions. While BEVs are zero emission vehicles, the electrical power generators used to recharge vehicle batteries do emit copious GHGs. Some analysts have estimated the power plant GHG emissions due to charging EV batteries using the average electrical generator grid mix for a given region. However, the GHG protocol specifies that analysts should use the marginal grid mixes to accurately calculate GHG emissions from adding EVs to the vehicle fleet. This paper utilizes the marginal grid mixes for each electrical power region in the US, and calculates the vehicle-weighted average GHG emissions for the entire country. These calculations demonstrate that, on the average, each BEV that displaces a gasoline hybrid electric vehicle (HEV) will increase GHGs by more than 7% and each PHEV put in service will increase GHGs by an average of 10% compared to a gasoline HEV.     

Lifecycle performance assessment of fuel cell/battery electric vehicles

This paper has performed an assessment of lifecycle (as known as well-to-wheels, WTW) greenhouse gas (GHG) emissions and energy consumption of a fuel cell vehicle (FCV). The simulation tool MATLAB/Simulink is employed to examine the real-time behaviors of an FCV, which are used to determine the energy efficiency and the fuel economy of the FCV. Then, the GREET (Greenhouse gases, Regulated Emissions, and Energy use in Transportation) model is used to analyze the fuel-cycle energy consumption and GHG emissions for hydrogen fuels. Three potential pathways of hydrogen production for FCV application are examined, namely, steam reforming of natural gas, water electrolysis using grid electricity, and water electrolysis using photovoltaic (PV) electricity, respectively. Results show that the FCV has the maximum system efficiency of 60%, which occurs at about 25% of the maximum net system power. In addition, the FCVs fueled with PV electrolysis hydrogen could reduce about 99.2% energy consumption and 46.6% GHG emissions as compared to the conventional gasoline vehicles (GVs). However, the lifecycle energy consumption and GHG emissions of the FCVs fueled with grid-electrolysis hydrogen are 35% and 52.8% respectively higher than those of the conventional GVs. As compared to the grid-based battery electric vehicles (BEVs), the FCVs fueled with reforming hydrogen from natural gas are about 79.0% and 66.4% in the lifecycle energy consumption and GHG emissions, respectively.     

Market penetration analysis of electric vehicles in the German passenger car market towards 2030

There is currently intensive public discussion of fuel cell electric vehicles (FCEV) and other electric powertrains, such as battery electric vehicles (BEV), plug-in hybrid electric vehicles (PHEV) and hybridized combustion engine vehicles (HEV). In this context, the German government has set the target of one million electric vehicles on the road by 2020, and six million by 2030 [1]. The goal of this paper is to identify the possible market share of electric vehicles in the German new car fleet in three scenarios in the timeframe from 2010 to 2030. The VECTOR21 vehicle technology scenario model is used to model the fleet in three scenarios. In the reference scenario with business-as-usual parameters, 189,000 electric vehicles will be sold in Germany by 2020. Scenario two with purchase price incentives from 5000 EUR, high oil prices, and low prices for hydrogen and electricity will result in 727,000 vehicles. In the last scenario with substantial OEM mark-up reductions and external conditions as in the business-as-usual scenario, 3.28 million vehicles will be sold.     

Disruptive innovations: The case for hydrogen fuel cells and battery electric vehicles

The investment of private money in technological innovation is driven by the expectation of successful market penetration. This decision to invest is less risky when the innovation represents gradual improvement of existing technologies. The term disruptive innovation is used to describe the opposite case, i.e. innovations that are so different that their establishment in the market causes a disruption to the pre-existing system. The existing literature on disruptive innovations provides us with historic case studies of successful market capture by new technologies, but this in itself is insufficient to clarify the chances of success for nascent technologies. This paper sets out to bring greater clarity to the characteristics of disruptive innovation in a way that informs the debate on the viability of emerging technologies. Whilst existing definitions are based on technologies that were successful, this paper proposes a three part criteria to define candidate disruptive technologies: disruption should relate to manufacturers and/or infrastructure (the two often being inter-related), whilst innovation must provide more than the equivalence of service to the end-user. A review of seven historical case studies of successful disruptive technologies reveals seven characteristics of candidate disruptive technologies at the stage of niche market penetration. Examining battery electric and hydrogen fuel cell vehicles against these seven characteristics, shows that both candidate disruptive technologies share the same challenges as those identified in the successful historic case studies and also helps to identify potential pathways to greater market penetration in the future for these technologies.     

Fuel economy of hydrogen fuel cell vehicles

On the basis of on-road energy consumption, fuel economy (FE) of hydrogen fuel cell light-duty vehicles is projected to be 2.5–2.7 times the fuel economy of the conventional gasoline internal combustion engine vehicles (ICEV) on the same platforms. Even with a less efficient but higher power density 0.6 V per cell than the base case 0.7 V per cell at the rated power point, the hydrogen fuel cell vehicles are projected to offer essentially the same fuel economy multiplier. The key to obtaining high fuel economy as measured on standardized urban and highway drive schedules lies in maintaining high efficiency of the fuel cell (FC) system at low loads. To achieve this, besides a high performance fuel cell stack, low parasitic losses in the air management system (i.e., turndown and part load efficiencies of the compressor–expander module) are critical.     

Roles of plug-in hybrid electric vehicles in the transition to the hydrogen economy

Closed-system regenerative fuel cells (RFCs) are an alternative to non-regenerative fuel cells as a transition technology and mainstay of a hydrogen economy. Substantially petroleum-free automobiles can spontaneously evolve from hybrid electric vehicles (HEVs) based solely on the economic viability of replacing batteries with RFCs as fuel cell prices decrease. The evolution can be projected first to plug-in HEVs (PHEVs) and finally to a substantially hydrogen-based transportation system.     

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.     

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.     

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:     

On the aggregate grid load imposed by battery health-conscious charging of plug-in hybrid electric vehicles

This article examines the problem of estimating the aggregate load imposed on the power grid by the battery health-conscious charging of plug-in hybrid electric vehicles (PHEVs). The article begins by generating a set of representative daily trips using (i) the National Household Travel Survey (NHTS) and (ii) a Markov chain model of both federal and naturalistic drive cycles. A multi-objective optimizer then uses each of these trips, together with PHEV powertrain and battery degradation models, to optimize both PHEV daily energy cost and battery degradation. The optimizer achieves this by varying (i) the amounts of charge obtained from the grid by each PHEV, and (ii) the timing of this charging. The article finally computes aggregate PHEV power demand by accumulating the charge patterns optimized for individual PHEV trips. The results of this aggregation process show a peak PHEV load in the early morning (between 5.00 and 6.00 a.m.), with approximately half of all PHEVs charging simultaneously. The ability to charge at work introduces smaller additional peaks in the aggregate load pattern. The article concludes by exploring the sensitivity of these results to the relative weighting of the two optimization objectives (energy cost and battery health), battery size, and electricity price.     

Fuel cell vehicles: Status 2007

Within the framework of this paper, a short motivation for hydrogen as a fuel is provided and recent developments in the field of fuel cell vehicles are described. In particular, the propulsion system and its efficiency, as well as the integration of the hydrogen storage system are discussed. A fuel cell drivetrain poses certain requirements (concerning thermodynamic and engineering issues) on the operating conditions of the tank system. These limitations and their consequences are described. For this purpose, conventional and novel storage concepts will be shortly introduced and evaluated for their automotive viability and their potential impact. Eventually, GM's third generation vehicles (i.e. the HydroGen3) are presented, as well as the recent 4th generation Chevrolet Equinox Fuel Cell SUV. An outlook is given that addresses cost targets and infrastructure needs.     

Comparative analysis of battery electric,hydrogen fuel cell and hybrid vehicles in a future sustainable road transport system

This paper compares battery electric vehicles (BEV) to hydrogen fuel cell electric vehicles (FCEV) and hydrogen fuel cell plug-in hybrid vehicles (FCHEV). Qualitative comparisons of technologies and infrastructural requirements, and quantitative comparisons of the lifecycle cost of the powertrain over 100,000 mile are undertaken, accounting for capital and fuel costs. A common vehicle platform is assumed. The 2030 scenario is discussed and compared to a conventional gasoline-fuelled internal combustion engine (ICE) powertrain. A comprehensive sensitivity analysis shows that in 2030 FCEVs could achieve lifecycle cost parity with conventional gasoline vehicles. However, both the BEV and FCHEV have significantly lower lifecycle costs. In the 2030 scenario, powertrain lifecycle costs of FCEVs range from $7360 to $22,580, whereas those for BEVs range from $6460 to $11,420 and FCHEVs, from $4310 to $12,540. All vehicle platforms exhibit significant cost sensitivity to powertrain capital cost. The BEV and FCHEV are relatively insensitive to electricity costs but the FCHEV and FCV are sensitive to hydrogen cost. The BEV and FCHEV are reasonably similar in lifecycle cost and one may offer an advantage over the other depending on driving patterns. A key conclusion is that the best path for future development of FCEVs is the FCHEV.