Performance and cost of fuel cells for urban air mobility

Several companies are developing enabling elements of urban air mobility (UAM) for air taxis, including prototypes of electric vertical take-off and landing (eVTOL) vehicles. These prototypes incorporate electric and hybrid powertrains for multi-rotor and tilt-rotor crafts. Many eVTOLS are using batteries for propulsion and charging them rapidly between the flights or swapping them for slow charging overnight. Rapid charging degrades the battery cycle life while swapping requires multiple batteries and charging stations. This study has conducted a technoeconomic evaluation of the eVTOL air taxis with alternate powertrains using hydrogen fuel cell systems being developed for light-duty and heavy-duty vehicles. We consider performance metrics such as fuel cell engine power, weight, and durability; hydrogen consumption and weight of storage system; and maximum take-off weight. The metrics for economic evaluation are capital cost, operating and maintenance cost, fuel cost, and the total cost of ownership (TCO). We compare the performance and TCO of battery, fuel cell and fuel cell – battery hybrid powertrains for multi-rotor and tilt-rotor crafts. We show that fuel cells are the only viable concept for powering multi-rotor eVTOLs on an urban scenario that requires 60-mile range, and hybrid fuel cells are superior to batteries as powertrains for tiltrotor eVTOLs.     

Affordable hydrogen supply pathways for fuel cell vehicles

Fuel cell vehicles can be powered directly by hydrogen stored on the vehicle, or indirectly by extracting hydrogen from onboard liquid fuels such as methanol or gasoline. The direct hydrogen fuel cell vehicle is preferred, since it would be less complex, have better fuel economy, lower greenhouse gas emissions, greater oil import reductions and would lead to a sustainable transportation system once renewable energy was used to produce hydrogen. The two oft-cited concerns with direct hydrogen fuel cell vehicles are onboard hydrogen storage and the lack of hydrogen supply options. Directed Technologies, Inc., working with the Ford Motor Company under a Department of Energy cost shared contract to develop direct hydrogen fuel cell vehicles, has addressed both perceived roadblocks to direct hydrogen fuel cell vehicles. We describe realistic, cost effective options for both onboard hydrogen storage and for economically viable hydrogen infrastructure development.     

Assessing the potential of fuel cell-powered and battery-powered forklifts for reducing GHG emissions using clean surplus power; a game theory approach

This work aims at developing a game theory model for assessing the potential of fuel cell-powered and battery-powered forklifts for reducing GHG emissions in the province of Ontario, Canada. Two stakeholders are considered in the developed model: government and energy consumer. The energy consumer, which is assumed to be an industrial facility, operates 150 diesel forklifts but has the option of replacing them with fuel cell-powered and battery-powered forklifts. The government can encourage this replacement by allocating a percentage of Ontario's surplus power to the energy consumer at a discounted price. The discount is assumed to be exempting the energy consumer from paying the global adjustment. As a result, the energy consumer only pays the hourly Ontario electricity price when discounted power is available. Discounted electricity will decrease the cost of operating battery-powered and fuel cell-powered forklifts for the energy consumer and will encourage it to use those technologies instead of diesel forklifts. The government has an incentive to pursue such policy as the replacement of diesel forklifts with fuel cell-powered and battery-powered forklifts will reduce GHG emissions and subsequently, the social cost of carbon in the province. The reults of our modeling show that when the government does not allocate discounted power to the energy consumer, energy consumer does not reduce emissions and keeps using its 150 diesel forklifts. However, when the government provides 0.1% of Ontario's surplus power at each hour to the energy consumer at a discounted price, the energy consumer replaces 31 of its diesel forklifts with battery-powered forklifts. When the percentage of discounted power is 0.6% of Ontario's surplus power at each hour, energy consumer replaces 91 of its diesel forklifts with battery-powered forklifts and 54 of its diesel forklifts with fuel cellpowered forklifts.A policy of discounting surplus power to encourage replacing diesel forklifts with battery-powered and fuel cell-powered forklifts is shown to benefit both stakeholders in the system. Our analysis also shows that the deployment of both fuel-cell powered and battery-powered forklifts is effective in reducing GHG emissions in Ontario when surplus clean power is available. Battery-powered forklifts are more cost-effective when lower levels of discounted power are available; however, with an increase in the level of available discounted power, fuel cell-powered forklifts become more cost-effective technologies compared to battery-powered forklifts.     

The impact of fuel cell vehicle deployment on road transport greenhouse gas emissions: The China case

Considerable attention has been paid to energy security and climate problems caused by road vehicle fleets. Fuel cell vehicles provide a new solution for reducing energy consumption and greenhouse gas emissions, especially those from heavy-duty trucks. Although cost may become the key issue in fuel cell vehicle development, with technological improvements and cleaner pathways for hydrogen production, fuel cell vehicles will exhibit great potential of cost reduction. In accordance with the industrial plan in China, this study introduces five scenarios to evaluate the impact of fuel cell vehicles on the road vehicle fleet greenhouse gas emissions in China. Under the most optimistic scenario, greenhouse gas emissions generated by the whole fleet will decrease by 13.9% compared with the emissions in a scenario with no fuel cell vehicles, and heavy-duty truck greenhouse gas emissions will decrease by nearly one-fifth. Greenhouse gas emissions intensity of hydrogen production will play an essential role when fuel cell vehicles' fuel cycle greenhouse gas emissions are calculated; therefore, hydrogen production pathways will be critical in the future.     

Comparative life cycle assessment of hydrogen pathways from fossil sources in China

Emissions of multiple hydrogen production pathways from fossil sources were evaluated and compared with that of fossil fuel production pathways in China by using the life cycle assessment method. The considered hydrogen pathways are gasoline reforming, diesel reforming, natural gas reforming, soybean‐derived biodiesel (s‐biodiesel) reforming, and waste cooking oil‐derived biodiesel reforming. Moreover, emissions and energy consumption of fuel cell vehicles utilizing hydrogen from different fossil sources were presented and compared with those of the electric vehicle, the internal combustion engine vehicle, and the compression ignition engine vehicle. The results indicate both fuel cell vehicles and the electric vehicle have less greenhouse gas emissions and energy consumption compared with the traditional vehicle technologies in China. Based on an overall performance comparison of five different fuel cell vehicles and the electric vehicle in China, fuel cell vehicles operating on hydrogen produced from natural gas and waste cooking oil‐derived biodiesel show the best performance, whereas the electric vehicle has the worse performance than all the fuel cell vehicles because of very high share of coal in the electricity mix of China. The emissions of electric vehicle in China will be in the same level with that of natural gas fuel cell vehicle if the share of coal decreases to around 40% and the share of renewable energy increases to around 20% in the electricity mix of China. Copyright © 2016 John Wiley & Sons, Ltd.     

Economic analysis of near-term California hydrogen infrastructure

A detailed economics model of hydrogen infrastructure in California has been developed and applied to assess several potential fuel cell vehicle deployment rate and hydrogen station technology scenarios. The model accounts for all of the costs in the hydrogen supply chain and specifically examines a network of 68 planned and existing hydrogen stations in terms of economic viability and dispensed hydrogen cost. Results show that (1) current high-pressure gaseous delivery and liquid delivery station technologies can eventually be profitable with relatively low vehicle deployment rates, and (2) the cost per mile for operating fuel cell vehicles can be lower than equivalent gasoline vehicles in both the near and long term.     

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.     

Hydrogen fuel cell heavy-duty trucks: Review of main research topics

Road transportation is a significant source of CO₂ emissions and energy demand. Consequently, initiatives are being promoted to decrease the sector's emissions and comply with the Paris agreement. This article synthesizes the available information about heavy-duty fuel cell trucks as their deployment needs to be considered a complementary solution to decreasing CO₂ emissions alongside battery electric vehicles. A thorough evaluation of 95 relevant documents determines that the main research topics in the past ten years converge on public policies, hydrogen supply chain, environmental impact, drivetrain technology, fuel cell, and storage tank applications. The identified research gaps relate to expanding collaboration between institutions and governments in developing joint green macro policies focused on hydrogen heavy-duty trucks, scarce research about hydrogen production energy sources, low interest in documenting hydrogen pilot projects, and minimal involvement of logistic companies, which need to plan their diesel freight's conversion as soon as possible.     

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.     

Prospects and impediments for hydrogen and fuel cell vehicles in the transport sector

Hydrogen and fuel cell vehicles are often discussed as crucial elements in the decarbonisation of the transport systems. However, in spite of the fact that hydrogen and fuel cell vehicles have a long history, they are still seen only as a long-term mobility option. The major objective of this paper is to analyse key barriers to the increasing use of hydrogen and fuel cell vehicles. A special focus is put on their economic performance, because this will be most crucial for their future deployment. Mobility costs are calculated based on the total cost of ownership, and future developments are analysed based on technological learning. The major conclusion is that to achieve full benefits of hydrogen and fuel cells in the transport sector, it is necessary to provide stabile, long-term policy framework conditions, as well as to harmonize actions across regions to be able to take advantage of economies of scale.     

Solar-powered hydrogen refuelling station for unmanned aerial vehicles: Design and initial AC test results

Fuel cell technology can offer environmental benefits (low noise and emissions) and also a competitive advantage over conventional power sources (better performance, low thermal signature, less vibration issues, etc) in small manned and unmanned electric air vehicles (UAVs). To develop an environmentally acceptable solution, the hydrogen fuel source must be produced on-site from renewable energy sources. This paper describes the development and testing of a fully operational small-scale demonstrator to generate and supply hydrogen for 2 to 3 daily fuel cell-powered UAV operations. The purity of the hydrogen delivered to the air platforms is ≥99.99%.     

Comparison of the technical potential for hydrogen,battery electric,and conventional light-duty vehicles to reduce greenhouse gas emissions and petroleum consumption in the United States

Light-duty vehicles (LDV) are responsible for a large fraction of petroleum use and are a significant source of greenhouse gas (GHG) emissions in the United States. Improving conventional gasoline-powered vehicle efficiency can reduce petroleum demand, however efficiency alone cannot reach deep GHG reduction targets, such as 80% below the 1990 LDV GHG emissions level. Because the cost and availability of low-GHG fuels will impose limits on their use, significant reductions in GHG emissions will require combinations of fuel and vehicle technologies that both increase efficiency and reduce the emissions from fuel production and use. This paper examines bounding cases for the adoption of individual technologies and then explores combinations of advanced vehicle and fuel technologies. Limits on domestic biofuel production—even combined with significant conventional combustion engine vehicle improvements—mean that hydrogen fuel cell electric or battery electric vehicles fueled by low-GHG sources will be necessary. Complete electrification of the LDV fleet is not required to achieve significant GHG reduction, as replacing 40% of the LDV fleet with zero-emission hydrogen vehicles while achieving optimistic biofuel production and conventional vehicle improvements can allow attainment of a low GHG emission target. Our results show that the long time scale for vehicle turnover will ensure significant emissions from the LDV sector, even when lower emission vehicles and fuels are widely available within 15 years. Reducing petroleum consumption is comparatively less difficult, and significant savings can be achieved using efficient conventional gasoline-powered vehicles.     

Off-grid solar powered charging station for electric and hydrogen vehicles including fuel cell and hydrogen storage

This paper designs an off-grid charging station for electric and hydrogen vehicles. Both the electric and hydrogen vehicles are charged at the same time. They appear as two electrical and hydrogen load demand on the charging station and the charging station is powered by solar panels. The output power of solar system is separated into two parts. On part of solar power is used to supply the electrical load demand (to charge the electric vehicles) and rest runs water electrolyzer and it will be converted to the hydrogen. The hydrogen is stored and it supplies the hydrogen load demand (to charge the hydrogen-burning vehicles). The uncertainty of parameters (solar energy, consumed power by electrical vehicles, and consumed power by hydrogen vehicles) is included and modeled. The fuel cell is added to the charging station to deal with such uncertainty. The fuel cell runs on hydrogen and produces electrical energy to supply electrical loading under uncertainties. The diesel generator is also added to the charging station as a supplementary generation. The problem is modeled as stochastic optimization programming and minimizes the investment and operational costs of solar and diesel systems. The introduced planning finds optimal rated powers of solar system and diesel generator, operation pattern for diesel generator and fuel cell, and the stored hydrogen. The results confirm that the cost of changing station is covered by investment cost of solar system (95%), operational cost of diesel generator (4.5%), and investment cost of diesel generator (0.5%). The fuel cell and diesel generator supply the load demand when the solar energy is zero. About 97% of solar energy will be converted to hydrogen and stored. The optimal operation of diesel generator reduces the cost approximately 15%.     

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.     

Life cycle assessment of hydrogen and diesel dual-fuel class 8 heavy duty trucks

Heavy-duty trucks, in particular class 8 tractor-trailer combinations for freight, are a major contributor to the total greenhouse gas (GHG) emissions in transportation systems worldwide. Diesel fuel vastly dominates this market due to its relatively low operating cost. However, both GHG and air pollutant emissions from diesel combustion are significant, which raises doubts about the long-term sustainability of this mode of transportation. A possible short-term opportunity to address this problem is to blend diesel with hydrogen by retrofitting existing fuel injection systems and fuel storage onboard the trucks. Thus, a life cycle assessment is conducted to evaluate the overall environmental and economic impacts of implementing hydrogen and diesel dual-fuel solutions in heavy-duty trucks. The results show a significant reduction in emissions, proportionally to the diesel displacement ratio. Importantly, the use of hydrogen fuel is also shown to provide potential cost savings in this highly cost-sensitive application for hydrogen pricing below C$4/kg. Hence, waste hydrogen available at low cost can facilitate immediate emission reduction and operational cost savings for existing truck fleets, and act as an economical bridge solution for sustainable heavy-duty freight.     

Future fuel cell and internal combustion engine automobile technologies: A 25-year life cycle and fleet impact assessment

Hydrogen fuel cell (FC) vehicles are receiving increasing attention as a potential powerful technology to reduce the transportation sector's dependence on petroleum and substantially decrease emissions of greenhouse gases (GHGs) at the same time. This paper projects energy use and GHG emissions from different FC vehicle configurations and compares these values to the projected characteristics of similarly sized and performing gasoline and diesel fueled automobiles on a life cycle, well to wheels and cradle to grave basis. Our analysis suggests that for the next 20 or more years, new internal combustion engine (ICE) hybrid drive train vehicles can achieve similar levels of reduction in energy use and GHG emissions compared to hydrogen FC vehicles, if the hydrogen is derived from natural gas. The fleet impact of more fuel-efficient vehicles depends on the time it takes for new technology to (i) become competitive, (ii) increase its share of the new vehicles produced, and finally (iii) penetrate significantly into the vehicle fleet. Since the lead times for bringing improved ICE vehicle technology into production are the shortest, its impact on vehicle fleet energy use and emissions could be significant in 20–30 years, about half the time required for hydrogen FC vehicles to have a similar impact. Full emission reduction potential of FC vehicles can only be achieved when hydrogen is derived from zero or very low-carbon releasing production processes on a large scale—an option that further increases the impact leadtime. Thus, a comprehensive short- and long-term strategy for reducing automobile energy use and emissions should include both the continuous improvement of ICE vehicles and simultaneous research and development of hydrogen FC cars.     

Performance analysis of various hybrid renewable energy systems using battery,hydrogen, and pumped hydro‐based storage units

The aim of this research is to analyze the techno‐economic performance of hybrid renewable energy system (HRES) using batteries, pumped hydro‐based, and hydrogen‐based storage units at Sharurah, Saudi Arabia. The simulations and optimization process are carried out for nine HRES scenarios to determine the optimum sizes of components for each scenario. The optimal sizing of components for each HRES scenario is determined based on the net present cost (NPC) optimization criterion. All of the nine optimized HRES scenarios are then evaluated based on NPC, levelized cost of energy, payback period, CO₂ emissions, excess electricity, and renewable energy fraction. The simulation results show that the photovoltaic (PV)‐diesel‐battery scenario is economically the most viable system with the NPC of US$2.70 million and levelized cost of energy of US$0.178/kWh. Conversely, PV‐diesel‐fuel cell system is proved to be economically the least feasible system. Moreover, the wind‐diesel‐fuel cell is the most economical scenario in the hydrogen‐based storage category. PV‐wind‐diesel‐pumped hydro scenario has the highest renewable energy fraction of 89.8%. PV‐wind‐diesel‐pumped hydro scenario is the most environment‐friendly system, with an 89% reduction in CO₂ emissions compared with the base‐case diesel only scenario. Overall, the systems with battery and pumped hydro storage options have shown better techno‐economic performance compared with the systems with hydrogen‐based storage.     

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.     

Life cycle cost analysis of a car,a city bus and an intercity bus powertrain for year 2005 and 2020

The international economy, in the beginning of the 20th century, is characterized by uncertainty about the supply and the price of oil. Together with the fast decrease of electrical propulsion component prices, it becomes more and more cost effective to develop vehicles with alternative powertrains. This paper focuses on two questions: Are alternative powertrains especially cost effective for specific applications?; How does an increased fossil fuel price influences the choose of powertrain? To assess these questions, a computer tool named THEPS, developed in a Ph.D. project, is used. Three applications and three scenarios are analysed. The applications, a car, a city bus and an intercity bus, are vehicles all assumed to operate in Sweden. One scenario represents year 2005, the other two year 2020. The two future scenarios are characterized by different fossil fuel prices. The study, presented in the paper, indicates that alternative powertrains can be competitive from a cost perspective, in some applications, already in year 2005. It is for example cost effective to equip a city bus, running in countries with a high fuel price, with a hybrid powertrain. The study also indicates that pure electric, hybrid and/or fuel cell cars will probably be a more cost effective choice than conventional cars in year 2020. Another indication is that it will not be clear which powertrain concept to choose. The reason is that many cost effective powertrain concepts will be offered. The best choice will depend on the application.     

Two-tier pressure consolidation operation method for hydrogen refueling station cost reduction

An operation strategy known as two-tier “pressure consolidation” of delivered tube-trailers (or equivalent supply storage) has been developed to maximize the throughput at gaseous hydrogen refueling stations (HRSs) for fuel cell electric vehicles (FCEVs). The high capital costs of HRSs and the consequent high investment risk are deterring growth of the infrastructure needed to promote the deployment of FCEVs. Stations supplied by gaseous hydrogen will be necessary for FCEV deployment in both the near and long term. The two-tier pressure consolidation method enhances gaseous HRSs in the following ways: (1) reduces the capital cost compared with conventional stations, as well as those operating according to the original pressure consolidation approach described by Elgowainy et al. (2014) [1], (2) minimizes pressure cycling of HRS supply storage relative to the original pressure consolidation approach; and (3) increases use of the station's supply storage (or delivered tube-trailers) while maintaining higher state-of-charge vehicle fills.