Fuel Cell Vehicles: Any Better in 2023?
The automotive industry is witnessing significant research and development in the areas of fuel cell vehicles (FCVs) and hybrid electric vehicles (HEVs). While the advantages of HEVs are well-established, there are still uncertainties surrounding FCVs in terms of cost-effectiveness, overall efficiency, performance, energy savings, and environmental impact. In this article, we will compare the performance and parameter characteristics of FCVs and HEVs, taking into account their drive train topologies, total cost, emissions, efficiency, and fuel economy.
Fuel Cell Vehicles (FCVs)
A fuel cell vehicle typically consists of a fuel cell stack, a power conversion stage, a controller, a traction motor, a transmission system, and wheels. In the case of a direct hydrogen FCV (DHFCV), the output voltage from each fuel cell is converted to usable power through a power electronic converter stage and then supplied to the motor based on an optimized control strategy. On the other hand, an indirect methanol FCV (IMFCV) supplies hydrogen to the fuel cell stack via an onboard reformer, and the power control unit supplies the required power by operating the reformer and the fuel cell stack.
Hybrid Electric Vehicles (HEVs)
HEVs come in two popular configurations: series hybrid and parallel hybrid. In a series hybrid, the electric motor is connected to the wheels, and an electric generator supplies electricity to the battery pack, which, in turn, feeds the traction motor. The engine/generator set maintains the battery charge, starting up when the battery is low and turning off when it reaches its upper limit. In a parallel hybrid, both the electric motor and the heat engine supply power to the wheels. The parallel hybrid topology does not require a generator, as the traction motor itself serves this purpose. There is also a series-parallel hybrid configuration, which combines the advantages of both series and parallel HEV topologies.
Cost Comparison and Emissions Reduction
When it comes to cost, HEVs are currently commercially available, while FCVs are still in the early research stage. The cost of FCVs is predicted to remain economically unfeasible for the next 15–20 years. While there is uncertainty regarding the long-term cost benefit of FCVs, research suggests that HEVs have a clear advantage in terms of cost, considering their use of existing infrastructure for conventional ICEVs.
Both FCVs and HEVs aim at reducing emissions through better control, cleaner fuels, and alternative transportation options. However, a complete analysis of vehicle-to-wheel emissions is crucial to determine their environmental advantages. Emission factors such as NOx, CO, SOx, and particulate matter (PM) need to be considered. It is assumed that advanced alternate fuel passenger cars will be available commercially in the US market by 2015.
Efficiency Comparison
HEVs offer improved efficiency over internal combustion engine vehicles (ICEVs). To assess efficiency, the well-to-wheels and vehicle-to-wheels efficiencies must be considered. The vehicle-to-wheel efficiency is the calculation based on the final use of fuel in a vehicle. HEVs have a significant advantage in terms of efficiency, while FCVs are still in need of further development to reach the desired goals.
Future Development and Goals
Automakers worldwide are actively developing alternative vehicles to ICEVs, with several prototype vehicles already built. Concepts such as fuel cell vehicles based on conventional vehicles with adjustments for the fuel cell system have been developed. However, the availability of refueling facilities for hydrogen is a major concern. Methanol has been considered as an alternative fuel for FCVs due to its similarities to gasoline, but large-scale production remains a challenge. Infrastructure for maintenance and repair facilities for FCVs and electrical and electronic components in HEVs also need further development.
Future research and development for FCVs primarily focus on advancements in driving range, maximum speed, and vehicle acceleration. Hybrid fuel cell/battery electric vehicles have the potential to exceed driving ranges depicted by pure battery electric vehicles. However, achieving these goals for FCVs is expected to take a considerable amount of time. Meanwhile, research on battery modules for energy storage in HEVs continues, and mild HEVs, using an integrated starter-alternator (ISA) with a 42 V electrical power system, are being developed.
HEVs have taken the lead in the automotive market due to the existing infrastructure for ICEVs, while FCVs face challenges in terms of refueling, repairs, maintenance, and infrastructure. Fuel cell vehicles are still far from commercialization, while HEVs have already entered the market. The development of fuel cell stacks, auxiliaries, and infrastructure remains crucial for FCVs. In the immediate future, hybrid electric vehicles offer the best option, considering their proximity to profitability. Fuel cell vehicles, though promising, require further research and development before they can become a commercially viable option, making transportation more environmentally friendly and efficient.
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