Hydrogen Fuel Cell Vehicles: Opportunities and Challenges

Abstract

This paper provides an in-depth review of the current state and future potential of hydrogen fuel cell vehicles (HFCVs). The urgency for more eco-friendly and efficient alternatives to fossil-fuel-powered vehicles underlines the necessity of HFCVs, which utilize hydrogen gas to power an onboard electric motor, producing only water vapor and heat. Despite their impressive energy efficiency ratio (EER), higher power-to-weight ratio, and substantial emissions reduction potential, the widespread implementation of HFCVs is presently hindered by several technical and infrastructural challenges. These include high manufacturing costs, the relatively low energy density of hydrogen, safety concerns, fuel cell durability issues, insufficient hydrogen refueling infrastructure, and the complexities of hydrogen storage and transportation. Nevertheless, technological advancements and potential policy interventions offer promising prospects for HFCVs, suggesting they could become a vital component of sustainable transportation in the future.

1. Introduction

Hydrogen energy is a versatile and clean energy source that has gained significant attention as a potential solution for addressing climate change and transitioning toward a sustainable energy future [1]. It has the potential to revolutionize various sectors, including transportation, power generation, and industrial processes. Hydrogen is the most abundant element in the universe but is primarily found in combination with other elements, such as oxygen in water (H₂O) or carbon in hydrocarbons [2]. To harness hydrogen as an energy source, it needs to be extracted and converted into a usable form. There are different methods for hydrogen production, including steam methane reforming, electrolysis, biomass gasification, and more [3]. Each method has its advantages and considerations in terms of efficiency, cost, and environmental impact.

One of the main advantages of hydrogen energy is its environmental benefits; when used as a fuel, hydrogen only produces water vapor as a byproduct, making it a zero-emission energy source [4]. This is particularly important in sectors such as transportation, where hydrogen fuel cells can be used to power electric vehicles, offering long driving ranges and fast refueling times. Furthermore, hydrogen energy has the potential to support renewable energy integration and energy storage [5]. Renewable energy sources such as solar and wind are intermittent, and their generation does not always align with energy demand. Hydrogen can be produced during times of excess renewable energy generation through electrolysis and stored for later use. It can be used for power generation when the renewable energy supply is low, thus providing a reliable and dispatchable energy option.

Hydrogen energy has emerged as a global destination for multiple sectors due to its potential to address various energy challenges and contribute to a sustainable future. Figure 1 shows the global hydrogen production (2010–2022).

The global destination for hydrogen energy is driven by its versatility, its potential for decarbonization, and its role in addressing various energy challenges. With increasing investments, supportive policies, and technological advancements, hydrogen energy is gaining momentum across multiple sectors globally, contributing to a sustainable and low-carbon future.

1.1. Hydrogen Types

Hydrogen energy can be categorized into different types based on its production methods and applications. Here are the main types of hydrogen energy:

• Gray hydrogen refers to hydrogen produced from fossil fuels, such as natural gas or coal, through a process called steam methane reforming (SMR). It is the most common method of hydrogen production today [8,9]. However, gray hydrogen production generates carbon dioxide (CO₂) emissions, contributing to climate change.
• Blue hydrogen is produced from fossil fuels, similar to gray hydrogen, but with an additional step called carbon capture and storage (CCS). The CCS involves capturing the CO₂ emitted during hydrogen production and storing it underground, preventing it from entering the atmosphere [10]. Blue hydrogen aims to reduce the carbon footprint of hydrogen production.
• Green hydrogen is produced using renewable energy sources, such as solar or wind power, through a process called electrolysis. Electrolysis involves splitting water (H₂O) into hydrogen (H₂) and oxygen (O₂) using an electric current [11,12]. Since it relies on renewable energy, green hydrogen production has no direct carbon emissions and is considered a clean and sustainable option.
• Turquoise hydrogen, also known as low-carbon or decarbonized hydrogen, is produced using natural gas but with carbon emissions offset by capturing and storing the CO₂, similar to blue hydrogen. The difference is that turquoise hydrogen production typically utilizes a different type of methane reforming process called methane pyrolysis, which can help in reducing the carbon intensity of hydrogen production [13].
• Brown hydrogen is produced from coal using gasification or other processes. It is considered the most carbon-intensive method of hydrogen production as it involves extracting hydrogen from coal, which is a high-carbon fossil fuel [14,15]. Brown hydrogen production generates substantial CO₂ emissions and is not considered a clean or sustainable option.
• Purple hydrogen is the hydrogen produced from nuclear energy sources, specifically through high-temperature electrolysis (HTE). This method utilizes heat generated by nuclear reactors to drive the electrolysis process, enabling the production of hydrogen without direct carbon emissions [16].

The green hydrogen only is considered the most environmentally friendly and sustainable option among these types as it relies on renewable energy sources. Blue and turquoise hydrogen, with the implementation of carbon capture and storage, can also help reduce the carbon footprint of hydrogen production. Figure 2 shows the global hydrogen production (2010–2022).

However, gray, brown, and purple hydrogen are associated with higher carbon emissions or environmental concerns. The development and adoption of green hydrogen, along with advancements in electrolysis technology and renewable energy integration, are key to achieving a cleaner and more sustainable hydrogen economy.

1.2. Hydrogen Production Methods

Hydrogen production is a key aspect of establishing a hydrogen economy. Currently, the majority of hydrogen is produced from fossil fuels, primarily natural gas, through a process of SMR. The SMR involves reacting methane (CH₄) with steam (H₂O) at high temperatures (700–1000 °C) in the presence of a catalyst [17]. The reaction produces hydrogen gas (H₂) and CO₂.

CH₄ + H₂O → CO₂ + 3H₂

(1)

However, the production of hydrogen from fossil fuels results in greenhouse gas emissions, which undermines the environmental benefits of using hydrogen as a clean energy source. Therefore, efforts are being made to develop and scale up low-carbon and renewable methods of hydrogen production.

• Electrolysis is a process that uses electricity to split water (H₂O) into hydrogen and oxygen. It requires an electric current to pass through water, which is typically achieved by using electrodes and an electrolyte [18]. The electrolysis reaction is as follows:

2H₂O → 2H₂ + O₂

(2)

There are two main types of electrolysis: alkaline electrolysis and proton exchange membrane (PEM) electrolysis. Alkaline electrolysis uses an alkaline electrolyte solution, while PEM electrolysis uses a solid polymer membrane as the electrolyte [19]. Electrolysis can be powered by renewable energy sources such as solar or wind power, resulting in renewable hydrogen production.

• Biomass gasification involves heating organic materials, such as wood chips or agricultural waste, in a controlled environment with limited oxygen supply. The process produces a mixture of gases, including hydrogen, carbon monoxide (CO), and methane (CH₄). Hydrogen can be separated from the gas mixture through various purification methods [20].

CxHyOz + Heat → CO + H₂ + CH₄ + Other Gases

(3)

Biomass gasification offers the advantage of utilizing organic waste materials and can contribute to a circular economy by reducing waste and producing renewable hydrogen.

• Photoelectrochemical water splitting (PEC) is a process that uses sunlight to split water molecules into hydrogen and oxygen. It involves a photoelectrochemical cell or photoelectrolysis system that utilizes a semiconductor material as a photoelectrode. When sunlight strikes the photoelectrode, it generates an electric current that drives the water splitting reaction [21,22].

2H₂O + Energy (sunlight) → 2H₂ + O₂

(4)

PEC water splitting has the potential to be a direct and efficient method of renewable hydrogen production, but it is still under development and faces challenges such as improving the efficiency of the photoelectrodes and reducing production costs.

In the context of HFCVs, PEC water splitting, or PEC hydrogen production, is particularly relevant. This process leverages sunlight to split water molecules into hydrogen and oxygen, providing a clean and renewable way to produce hydrogen for HFCVs. The challenge lies in finding a suitable semiconductor material that can absorb a significant portion of the solar spectrum, generate a sufficiently high photovoltage to drive the water splitting reactions, and remain stable under the operation conditions. Many research efforts are currently dedicated to finding efficient and cost-effective materials and designs for PEC cells. From the perspective of HFCVs, PEC hydrogen production could provide a sustainable and carbon-neutral source of hydrogen fuel. However, substantial improvements in the efficiency and scalability of PEC processes are needed for them to be viable on a large scale. Technological advancements in this area could help address one of the major challenges facing HFCVs—the sustainability and environmental footprint of hydrogen production—as outlined in the article.

• Thermochemical processes involve the use of heat to produce hydrogen from various chemical reactions. One example is the sulfur–iodine (S–I) thermochemical cycle, which consists of a series of chemical reactions that utilize sulfur and iodine compounds to produce hydrogen [23]. These processes are typically complex and require high temperatures and specialized materials.
• Biological processes involve using microorganisms or enzymes to produce hydrogen through biological reactions. For example, certain bacteria are capable of producing hydrogen through fermentation or photosynthesis. Biological processes have the potential for sustainable hydrogen production, but further research is needed to optimize their efficiency and scalability [24].

1.3. Current Status of Hydrogen Energy

The utilization of hydrogen energy is rapidly advancing, although it is still in the early stages of commercialization and deployment. Various countries and industries are actively exploring and investing in hydrogen technologies to harness its potential as a clean and sustainable energy source.

Transportation: One of the main areas where hydrogen energy is being explored is transportation. The HFCVs are electric vehicles that use hydrogen as a fuel source. In these vehicles, hydrogen gas is combined with oxygen from the air in a fuel cell to produce electricity, which powers an electric motor [25]. The only byproduct of this process is water vapor, making fuel cell vehicles zero-emission vehicles. Fuel cell vehicles offer several advantages, including longer driving ranges and shorter refueling times compared with battery electric vehicles. However, their commercial adoption is still limited due to challenges such as high costs, limited hydrogen refueling infrastructure, and the need for further advancements in fuel cell technology [26].

Power generation: Hydrogen can also be used in power generation to produce electricity; this can be done through the use of hydrogen fuel cells or by burning hydrogen in a combustion engine. In a fuel cell, hydrogen reacts with oxygen from the air to produce electricity, heat, and water vapor [27]. This process is highly efficient and emits no greenhouse gases when renewable hydrogen is used. Hydrogen combustion is another method of utilizing hydrogen for power generation. In this process, hydrogen is burned in a turbine or internal combustion engine, similar to the combustion of natural gas. However, the combustion of hydrogen produces only water vapor as a byproduct, making it a clean and environmentally friendly option [28].

Industrial applications: Hydrogen is widely used in various industrial applications. It is an important component in the production of ammonia, which is used as a fertilizer and in the production of chemicals. Hydrogen is also used in the petroleum refining process to remove impurities from crude oil and to produce cleaner fuels. Hydrogen is utilized in the steel industry for the direct reduction of iron ore to produce iron. It can also be used in the production of methanol, an important chemical used in various industries [29,30].

1.4. Study Objective

The primary objective of the study is to comprehensively understand the current state of HFCVs technology and its potential role in shaping future transportation systems. The specific objectives of this study are as follows:

• Understand the principles of HFCVs: To delve into the science and engineering behind hydrogen fuel cell technology, understanding how it works and its potential applications in the transportation sector.
• Evaluate the opportunities: To identify and analyze the potential advantages offered by HFCVs, such as their environmental benefits, energy efficiency, and potential to reduce dependence on fossil fuels.
• Identify the challenges: To examine the current hurdles faced by HFCV technology, which could include issues related to hydrogen production, storage, infrastructure, and the cost of vehicles.
• Review the market dynamics: To evaluate the present market landscape for HFCVs, including key players, competition with other technologies (like battery electric vehicles), and regulatory impacts.
• Investigate the future prospects: To predict the potential future of HFCVs, considering ongoing research, upcoming technological advancements, and global trends in sustainable transportation.
• Develop recommendations: To develop actionable recommendations for stakeholders in the HFCVs industry, from policymakers to automotive manufacturers, regarding strategies for addressing the identified challenges and opportunities.

By accomplishing these objectives, the study aims to provide a holistic perspective on the potential role of HFCVs in achieving sustainable and efficient transportation systems in the future.

2. Hydrogen Fuel Cell Vehicles

The HFCVs have emerged as a promising solution, offering a pathway to cleaner and more sustainable transportation. Harnessing the power of hydrogen, the most abundant element in the universe, HFCVs represent a paradigm shift in the automotive industry, providing zero-emission mobility without compromising on performance or range. The innovative technology behind these vehicles holds great potential to revolutionize the way to travel, addressing the detrimental impacts of traditional internal combustion engines [30]. Figure 3 shows the progress of the global HFCVs as a percentage of the total vehicles for the period of (2010–2022).

Several countries around the world have been actively promoting and adopting hydrogen fuel cell cars as part of their efforts to reduce greenhouse gas emissions and transition to clean transportation. Some countries that have been at the forefront of using hydrogen fuel cell cars are the following:

Japan has been a pioneer in hydrogen fuel cell technology and has made significant investments in infrastructure and vehicle deployment. The country has been promoting HFCVs through various initiatives and collaborations with automakers. The Toyota Mirai, Honda Clarity Fuel Cell, and other models are available in Japan, and the country has been expanding its hydrogen refueling station network [32].

Republic of Korea has been actively promoting hydrogen as an alternative fuel for transportation. The government has set targets to have 6.2 million hydrogen vehicles on the roads by 2040. Hyundai, a Republic of Korea automaker, has been leading in the production of fuel cell vehicles, including the Hyundai NEXO. The country has been investing in building hydrogen infrastructure, including refueling stations [33].

Germany has been working toward promoting HFCVs as part of its transition to clean energy and reducing dependence on fossil fuels. The German government has been providing financial incentives to support the purchase of fuel cell vehicles. Companies like BMW and Audi have developed hydrogen-powered concept cars, and there are ongoing efforts to expand the hydrogen refueling infrastructure [34,35].

The United States has been making progress in the adoption of HFCVs. California, in particular, has been a leader in promoting HFCVs, with several hydrogen refueling stations available across the state. Automakers like Toyota, Honda, and Hyundai offer fuel cell models in certain regions. The U.S. federal government and state governments have been providing incentives to encourage the adoption of fuel cell vehicles [36].

China has been investing heavily in hydrogen energy and fuel cell technology. The country aims to become a global leader in hydrogen and has set targets to have over one million HFCVs on the roads by 2030 [37,38]. Chinese automakers, such as BYD and Geely, have been developing and producing HFCVs, and the government has been supporting the construction of hydrogen refueling stations [39,40].

Other countries, including France, the United Kingdom, Canada, and Norway, have also shown interest and taken steps to promote the adoption of HFCVs, although the scale of deployment varies [41]. The development and adoption of hydrogen fuel cell cars are part of a broader global effort to transition to sustainable and low-carbon transportation alternatives. Figure 4 shows the percentage of used HFCVs to the total number of vehicles in each country for the year 2021.

2.1. HFCV Overview

Hydrogen fuel cell technology represents a breakthrough in the quest for sustainable and environmentally friendly energy sources. This innovative technology leverages the energy stored in molecular hydrogen, converting it into electricity through a series of chemical reactions and producing only water and heat as byproducts. As such, it offers considerable promise, particularly in the field of transportation, as a clean and efficient alternative to conventional fossil-fuel-based internal combustion engines.

The central component of hydrogen fuel cell technology is the fuel cell stack. This consists of two electrodes—an anode and a cathode—separated by an electrolyte layer. The fuel cell operates through several interlinked chemical reactions [44,45]:

• Hydrogen supply: Stored in high-pressure tanks within the vehicle, hydrogen gas is delivered to the anode of the fuel cell stack.
• Hydrogen ionization: Once at the anode, a platinum catalyst assists in the ionization of hydrogen molecules, splitting each into two hydrogen ions (protons) and two electrons.
• Ion and electron separation: The electrolyte, commonly a proton exchange membrane (PEM), permits only the positively charged hydrogen ions to move through to the cathode. This forces the electrons to travel via an external circuit to reach the cathode, thereby generating an electric current.
• Oxygen reduction and water formation: At the cathode, oxygen from the ambient air is reduced and merges with the incoming hydrogen ions and electrons to generate water—the technology’s sole exhaust product.
• Power generation: The electric current produced by the flow of electrons powers the vehicle’s electric motor and other auxiliary systems such as the headlights, heating, and air conditioning.

Significantly, while the vehicle is operational, these reactions take place continuously, providing a consistent source of electricity for as long as hydrogen and oxygen remain available. This technology, although still developing, has notable benefits. Hydrogen fuel cells are more energy-efficient than traditional combustion engines, and the fuel—hydrogen—can be derived from a variety of sources, including renewables. Nevertheless, challenges persist, including safe and efficient hydrogen storage and the need for cost-effective, environmentally friendly hydrogen production. Despite these obstacles, hydrogen fuel cell technology holds substantial potential and could play a pivotal role in driving a sustainable future in transportation.

2.2. Working Principle of HFCVs

The HFCVs operate based on the electrochemical reactions occurring in a device called a fuel cell. This fuel cell combines hydrogen and oxygen to produce electricity, which is then used to power the vehicle electric motor as follows [46,47]:

• Hydrogen supply: Hydrogen gas, stored in a high-pressure tank within the vehicle, is supplied to the anode side of the fuel cell.
• Hydrogen ionization: At the anode, a catalyst, usually made of platinum, facilitates the ionization of hydrogen. Each hydrogen molecule (H₂) is split into two hydrogen ions (protons) and two electrons [48]:

  H₂ → 2H⁺ + 2e⁻

  (5)
• Ion and electron separation: The proton exchange membrane (PEM) in the middle of the fuel cell only allows protons to pass through it, while the electrons are forced to travel along an external circuit to reach the other side (the cathode). This movement of electrons creates an electric current.
• Oxygen reduction and water formation: At the cathode side, oxygen from the air is reduced and combined with the incoming protons and the electrons that have traveled through the external circuit. This reaction forms water, which is expelled as the only byproduct [49]:

  O₂ + 4H⁺ + 4e⁻ → 2H₂O

  (6)
• Power generation: the electricity generated (the flow of electrons) is harnessed to power the vehicle electric motor and other electrical systems [50].

The overall reaction in the fuel cell, therefore, can be summed up as

2H₂ + O₂ → 2H₂O + Electrical energy

(7)

The kinetics and thermodynamics of the reactions in a hydrogen fuel cell, which underpin the functioning of HFCVs, primarily involve two processes: the breaking of the H–H bond in hydrogen molecules and the formation of the O–H bond in water molecules. These processes happen in the two halves of the fuel cell: the anode (where hydrogen gas is supplied) and the cathode (where oxygen from the air is supplied).

The thermodynamics of these reactions whether they occur spontaneously depend on the Gibbs free energy change (∆G). This quantity can be calculated from the equation

∆G = ∆H − T∆S

(8)

where ∆H is the enthalpy change, T is the absolute temperature, and ∆S is the entropy change.

In a hydrogen fuel cell, the enthalpy change is primarily due to the difference in energy between the breaking of H–H bonds and the formation of O–H bonds. The entropy change is usually negative as the reaction leads to a decrease in the number of gas molecules.

The Gibbs free energy change is also related to the electrochemical potential (E) of the fuel cell by

∆G = −nFE

(9)

where n is the number of electrons transferred per molecule of hydrogen (n = 2), F is the Faraday constant, and E is the cell potential. The cell potential is what drives the electric current in the external circuit.

While the exact values of ∆G, ∆H, and ∆S depend on the specific design and operating conditions of the fuel cell, it is the favorable thermodynamics (negative ∆G) and fast kinetics (thanks to catalysts) of the hydrogen oxidation and oxygen reduction reactions that make HFCVs a promising technology for sustainable transportation. However, challenges remain in terms of improving the efficiency and durability of the fuel cell and reducing the cost of the catalysts, as discussed in the article.

2.3. Rationale of HFCVs

The HFCVs offer a compelling solution to address the environmental challenges associated with conventional transportation systems. Their working principle, based on electrochemical reactions and the utilization of hydrogen as a clean fuel source, enables emission-free mobility and improved energy efficiency. Studying HFCVs is justified by the need to combat climate change, reduce dependence on finite fossil fuel resources, promote sustainable energy systems, enhance energy security, drive technological advancements, and integrate renewable energy sources. The decision to study HFCVs is driven by various compelling factors, primarily stemming from growing environmental concerns and the diminishing availability of fossil fuel resources.

Environmental concerns and climate change: One of the most pressing global challenges faced today is climate change. The transportation sector is a significant contributor to greenhouse gas emissions, with conventional internal combustion engine vehicles being a major source of CO₂ and other harmful pollutants. By transitioning to HFCVs, it can significantly reduce emissions of CO₂, nitrogen oxides (NO_X), and particulate matter, thus mitigating the adverse effects of climate change and improving air quality [51].

Depletion of fossil fuels: The finite nature of fossil fuel reserves raises concerns about their long-term availability and the economic stability associated with their extraction. As the world becomes increasingly aware of the need to diversify energy sources, hydrogen emerges as a viable alternative [52]. Hydrogen is the most abundant element in the universe and can be produced from a variety of renewable sources, such as water electrolysis powered by renewable energy, making it an attractive option for sustainable transportation.

Energy efficiency and sustainability: Compared with conventional combustion engines, fuel cell technology offers higher energy conversion efficiencies. Hydrogen fuel cells have the potential to achieve efficiencies of up to 60%, significantly surpassing the typical 20–30% efficiency range of internal combustion engines [53]. By harnessing the inherent efficiency of fuel cells and renewable hydrogen production methods, HFCVs can contribute to a more sustainable energy system.

Energy independence and security: The development of HFCVs also holds the promise of reducing dependence on foreign oil imports. By diversifying the energy mix and utilizing locally produced hydrogen, countries can enhance their energy security and reduce vulnerabilities associated with geopolitical tensions and fluctuations in oil prices [54].

Technological advancements and innovation: The study of HFCVs is essential to foster technological advancements and innovation. Continued research and development efforts are needed to enhance the performance, efficiency, and durability of fuel cells, as well as to address challenges related to hydrogen storage, infrastructure development, and cost reduction. By investing in these areas, it can accelerate the commercialization and widespread adoption of HFCVs, driving the transformation of the transportation sector [55].

Synergy with renewable energy sources: Hydrogen fuel cells can act as enablers for the integration of renewable energy sources into the transportation sector. By using surplus renewable energy, such as wind or solar power, to produce hydrogen through electrolysis, HFCVs can effectively store and utilize this energy when the demand exceeds the supply [56]. This synergy between hydrogen production and renewable energy integration can facilitate a cleaner and more reliable energy system.

As progress toward a more sustainable future, HFCVs have the potential to revolutionize the transportation sector, mitigate environmental impacts, and foster a greener and more resilient global economy. By investing in research, infrastructure, and policy frameworks that support the adoption of HFCVs, we can pave the way for a sustainable transportation revolution that will benefit present and future generations.

3. Hydrogen Fuel Cell Vehicle Technology

The technology of HFCVs is an innovative approach to powering automobiles that utilizes hydrogen as its primary fuel. At the heart of this technology is a device called a fuel cell, which uses hydrogen to produce electricity within the vehicle, powering the electric motor and offering a clean alternative to traditional internal combustion engines.

3.1. Fuel Cell Technology and Its Use in Vehicles

Fuel cell technology is the backbone of HFCVs, which involves the electrochemical conversion of hydrogen fuel into electrical energy, which can be used to power the vehicle’s electric motor. The primary components of a fuel cell include an anode, a cathode, and an electrolyte.

When hydrogen (H₂) is supplied to the anode of the fuel cell, it undergoes a process called hydrogen oxidation. In this process, hydrogen molecules are split into protons (H⁺) and electrons (e⁻) through a reaction facilitated by a catalyst (usually platinum) [57,58]:

H₂ → 2H⁺ + 2e⁻

The protons migrate through the electrolyte, while the electrons travel through an external circuit, creating an electric current that can be utilized to power the vehicle motor. At the cathode, oxygen from the air combines with the protons and electrons to form water as the only byproduct [59]:

O₂ + 4H⁺ + 4e⁻ → 2H₂O

This electrochemical reaction produces a continuous flow of electricity, allowing for sustained vehicle operation. The fuel cell system can be designed in various configurations, such as proton exchange membrane fuel cells (PEMFCs), alkaline fuel cells (AFCs), phosphoric acid fuel cells (PAFCs), and solid oxide fuel cells (SOFCs), with PEMFCs being the most commonly used in HFCVs.

3.2. The Chemistry behind Hydrogen Fuel Cells

The chemical process behind hydrogen fuel cells revolves around the electrochemical reactions that occur within the fuel cell. These reactions are governed by principles of redox (reduction–oxidation) reactions and involve the movement of charged particles, protons, and electrons.

The anode of the fuel cell is where hydrogen oxidation takes place. The hydrogen molecules dissociate into protons and electrons due to the catalytic effect of the platinum catalyst. The protons (H⁺) are small, positively charged particles that can easily pass through the electrolyte, typically a proton exchange membrane (PEM), while the electrons (e⁻) flow through an external circuit to create an electric current [59].

At the cathode, oxygen from the air combines with the protons and electrons to form water. This process is known as oxygen reduction:

O₂ + 4H⁺ + 4e⁻ → 2H₂O

The overall reaction in a hydrogen fuel cell can be represented as

2H₂ + O₂ → 2H₂O

This reaction demonstrates that the only byproduct of the fuel cell system is water, making it a clean and environmentally friendly energy conversion technology.

3.3. The Design and Structure of a Hydrogen Fuel Cell Vehicle

The HFCVs are designed to incorporate the fuel cell system, hydrogen storage, and electric drivetrain components. The key elements of the design and structure of an HFCV include [60,61] the following:

• Fuel cell stack: The heart of the HFCV is the fuel cell stack, which contains multiple individual fuel cells. Each fuel cell consists of an anode, a cathode, and an electrolyte. The fuel cell stack generates electrical energy from the chemical reaction between hydrogen and oxygen.
• Hydrogen storage: HFCVs require a mechanism to store hydrogen fuel on board the vehicle. Common methods of hydrogen storage include high-pressure compressed gas cylinders or cryogenic liquid hydrogen tanks. These storage systems ensure the safe and efficient containment of hydrogen fuel.
• Electric motor: The electrical energy produced by the fuel cell stack powers an electric motor, which drives the wheels of the vehicle [62]. The electric motor offers smooth acceleration and quiet operation, contributing to the overall performance and efficiency of the HFCVs.
• Power control unit: The power control unit manages the flow of electrical energy from the fuel cell stack to the electric motor. It regulates the voltage and current to ensure optimal performance and efficiency.
• Auxiliary systems: HFCVs also incorporate auxiliary systems, such as cooling systems to maintain the optimal operating temperature of the fuel cell stack, as well as air supply systems to provide oxygen for the fuel cell reaction.
• Energy storage: Some HFCVs also include energy storage systems, such as lithium-ion batteries, to capture and store excess electrical energy produced by the fuel cell stack. These energy storage systems can be used to provide additional power during high-demand situations or for regenerative braking.

3.4. Current Models of HFCVs in the Market

Several automakers have introduced HFCVs to the market; however, the availability of specific models varies depending on the region and market.

Table 1. A comparison between popular HFCVs.

Aspect	Toyota Mirai	Hyundai NEXO	Honda Clarity Fuel Cell	Mercedes-Benz GLC F-CELL	Audi A7 H-Tron Quattro
Vehicle type	Sedan	SUV	Sedan	SUV	Sedan
Seating capacity	4	5	5	5	4
Range (approximate)	805 km	612 km	579 km	500 km	N/A
Refueling time (compressed hydrogen)	3–5 min	5 min	3–5 min	N/A	N/A
Power output	182 hp	161 hp	174 hp	208 hp	N/A
Torque	221 lb-ft	291 lb-ft	221 lb-ft	258 lb-ft	N/A
Key features	Advanced safety systems	Extensive safety features	Honda Sensing Suite	Plug-in hybrid capability	Concept vehicle
Availability (as of knowledge cutoff)	Available	Available	Available	Limited availability	Concept vehicle

shows the global most popular models of HFCVs that were available or announced by major automakers at that time.

• The Toyota Mirai is one of the most well-known hydrogen HFCVs. It has been available in select markets since 2014 and has undergone several generations of updates [63]. The latest generation of the Mirai offers improved range, performance, and design.
• The Hyundai NEXO is another commercially available hydrogen HFCV. It offers an estimated range of over 600 km and features advanced driver assistance systems and a spacious interior [64].
• The Honda Clarity Fuel Cell is a hydrogen HFCV that has been available for lease in certain regions [65]. It offers seating for up to five passengers.
  The Honda Clarity Fuel Cell is a hydrogen HFCV that has been available for lease in certain regions [65]. It offers seating for up to five passengers.
• The Mercedes-Benz GLC F-CELL was introduced as a plug-in hybrid HFCV. It combined a fuel cell system with a rechargeable battery, offering both hydrogen fuel cell and battery electric driving modes.
• The Audi A7 h-tron Quattro, as showcased by Audi, was a hydrogen HFCV concept vehicle. It featured a fuel cell system coupled with a plug-in hybrid configuration, providing extended range and flexibility [66].

The availability and model lineup of HFCVs are continuously evolving as automakers and governments work toward promoting hydrogen infrastructure and expanding the market for these vehicles. New models and updates to existing models may have been introduced since our knowledge cutoff, so it is recommended to consult the latest information from automakers and dealerships for the most up-to-date offerings in the HFCV market.

The percentages are approximate of the popularity, and the market presence of the mentioned HFCV is always subject to change. Figure 5 shows the percentage of used HFCVs to the total number of vehicles for the year 2021.

The actual market shares and best-selling percentages can vary significantly depending on factors such as the region, market demand, availability, and other factors.

4. Opportunities for HFCVs

4.1. Opportunities Associated with HFCVs

The HFCVs offer several advantages and opportunities compared with conventional internal combustion engine vehicles. These advantages and opportunities stem from the unique characteristics of hydrogen as a fuel and the efficient and clean operation of fuel cell technology. This section highlights some of the advantages and opportunities associated with HFCVs:

• Zero emissions: HFCVs produce zero tailpipe emissions as the only byproduct of the electrochemical reaction is water vapor. This makes HFCVs an environmentally friendly alternative to conventional vehicles, contributing to improved air quality and reduced greenhouse gas emissions [67].
• Energy efficiency: Fuel cells can achieve higher energy conversion efficiencies compared with internal combustion engines. The direct conversion of chemical energy into electrical energy in fuel cells results in less wasted energy, leading to greater overall efficiency and reduced energy consumption.
• Extended range and quick refueling: HFCVs typically offer longer driving ranges compared with battery electric vehicles. Hydrogen fueling stations can refill a fuel cell vehicle in a matter of minutes, similar to the refueling time for conventional vehicles [68]. This addresses concerns about range anxiety and long recharging times associated with battery electric vehicles.
• Scalability and flexibility: Hydrogen fuel cell technology can be scaled for various applications, from small portable devices to large-scale power generation. It offers flexibility in energy sources as hydrogen can be produced from diverse resources such as renewable energy (e.g., solar and wind) or by reforming fossil fuels [69]. This scalability and flexibility enable the decarbonization of various sectors, including transportation, power generation, and industrial processes.
• Energy storage and grid integration: Hydrogen can serve as an energy storage medium. Excess electricity generated from renewable sources can be used to produce hydrogen through electrolysis, which can be stored and later used in fuel cells to generate electricity. This integration of hydrogen fuel cells with renewable energy sources supports the development of a sustainable and resilient energy system, enabling the utilization of intermittent renewable energy and helping to balance the grid [70].
• Fast refueling infrastructure deployment: Compared with the widespread deployment of electric vehicle charging infrastructure, establishing hydrogen refueling infrastructure is relatively quick. Existing natural gas pipelines can be repurposed for hydrogen transportation, and new hydrogen refueling stations can be built using modular and scalable designs. This provides an opportunity for accelerated infrastructure development, especially for long-haul transportation and heavy-duty applications.
• Quiet operation and comfort: Fuel cell vehicles produce significantly less noise compared with conventional vehicles with internal combustion engines. This leads to quieter and more comfortable driving experiences, reducing noise pollution in urban areas.
• Economic development and job creation: The development and deployment of hydrogen fuel cell technologies and infrastructure offer opportunities for economic growth and job creation. The hydrogen sector encompasses research and development, manufacturing, the installation and maintenance of fuel cell systems, hydrogen production and distribution, and the operation of refueling stations [71].

The HFCVs offer advantages such as zero emissions, high energy efficiency, extended range, quick refueling, scalability, flexibility in energy sources, energy storage capabilities, fast infrastructure deployment, quiet operation, and economic development opportunities. These advantages and opportunities position HFCVs as a promising and sustainable solution for the transportation sector and the broader transition to a low-carbon economy.

4.2. Potential for Zero-Emission Transportation and Reduced Dependence on Fossil Fuels

Fuel cell vehicles have the potential to contribute significantly to achieving zero-emission transportation and reducing dependence on fossil fuels. Here are the reasons why fuel cell vehicles offer these advantages [72,73]. Figure 6 shows the opportunities of HFCVs’ potential for zero-emission transportation and reduced dependence on fossil fuels.

• Zero-emission transportation: Fuel cell vehicles produce zero tailpipe emissions, making them a key solution for reducing air pollution and mitigating climate change. The only byproduct of the electrochemical reaction in fuel cells is water vapor. Unlike internal combustion engine vehicles that emit greenhouse gases such as CO₂ and pollutants (such as nitrogen oxides and particulate matter), fuel cell vehicles operate with minimal environmental impact.
• Clean and efficient energy conversion: Fuel cells offer a highly efficient method of converting chemical energy directly into electrical energy. The electrochemical process that occurs within the fuel cell enables a more efficient utilization of fuel compared with the combustion process in internal combustion engines. This efficiency leads to reduced fuel consumption and lower greenhouse gas emissions per kilometer driven.
• Reduced dependence on fossil fuels: Hydrogen, the primary fuel for fuel cell vehicles, can be produced from diverse sources, including renewable energy. By using renewable energy sources such as wind, solar, and hydroelectric power to produce hydrogen through electrolysis, fuel cell vehicles can help reduce dependence on fossil fuels for transportation. This enhances energy security and promotes a more sustainable and diversified energy mix.
• Energy storage and grid integration: Fuel cell vehicles can play a crucial role in energy storage and grid integration. Excess electricity generated from renewable sources can be used to produce hydrogen through electrolysis, which can then be stored for later use in fuel cells. This enables the utilization of intermittent renewable energy, helps balance the electrical grid, and promotes the efficient integration of renewable energy sources.
• Renewable hydrogen production: The production of hydrogen for fuel cells can be achieved using renewable energy sources, ensuring that the entire fuel cycle is environmentally friendly. By utilizing renewable energy in hydrogen production, fuel cell vehicles can achieve a truly sustainable and zero-emission transportation solution.
• Decentralized energy generation: Fuel cell vehicles, combined with hydrogen refueling infrastructure, offer the potential for decentralized energy generation. On-site hydrogen production from renewable sources can enable localized energy generation and reduce the need for long-distance energy transportation. This decentralization of energy generation can enhance energy resilience and reduce transmission losses.

The fuel cell vehicles have the potential to provide zero-emission transportation and reduce dependence on fossil fuels. With their ability to operate with high energy efficiency and utilize renewable hydrogen, fuel cell vehicles offer a sustainable and environmentally friendly solution for the transportation sector, contributing to cleaner air, reduced greenhouse gas emissions, and a more diversified and resilient energy system.

4.3. HFCVs’ Contributions to a Sustainable Energy Ecosystem

The HFCVs have the potential to contribute significantly to the development of a sustainable energy ecosystem. Here are some ways in which HFCVs can contribute to a sustainable energy ecosystem [74,75]:

• Renewable energy integration: HFCVs can facilitate the integration of renewable energy sources, such as solar and wind, into the transportation sector. Excess electricity generated from renewable sources can be used for hydrogen production through electrolysis. This enables the storage of renewable energy in the form of hydrogen, which can then be used in HFCVs to generate electricity. By utilizing hydrogen produced from renewable sources, HFCVs can help balance the intermittency of renewable energy and contribute to the efficient utilization of renewable resources.
• Grid balancing and energy storage: HFCVs equipped with hydrogen fuel cells can act as distributed energy storage systems. During periods of high electricity demand or low renewable energy generation, HFCVs can provide stored energy by generating electricity from stored hydrogen. This enhances the grid stability, reduces the strain on the electrical grid, and improves the overall energy management. The stored hydrogen can be dispatched for power generation or to supply other energy-intensive sectors during peak demand periods.
• Decentralized power generation: HFCVs, when coupled with stationary fuel cells, can enable decentralized power generation. Hydrogen produced from renewable sources can be used not only for fueling vehicles but also for stationary fuel cells that generate electricity. This decentralized approach to power generation can reduce transmission losses and enhance energy resilience, particularly in remote areas or during natural disasters where the traditional power infrastructure may be disrupted.
• Fuel cell combined heat and power (CHP) systems: HFCVs equipped with fuel cells can contribute to combined heat and power (CHP) systems. The waste heat generated by the fuel cell during electricity generation can be captured and used for various heating applications, such as residential and commercial space heating or industrial processes. This increases the overall energy efficiency and reduces the need for separate heating systems, leading to energy savings and lower greenhouse gas emissions.
• Renewable hydrogen production: The production of hydrogen for HFCVs can be achieved using renewable energy sources, ensuring that the entire fuel cycle is environmentally friendly. By utilizing renewable energy in hydrogen production through electrolysis, HFCVs can achieve a truly sustainable transportation solution. This renewable hydrogen can be produced on site or at centralized facilities, further promoting the use of clean energy sources.
• Circular economy approach: HFCVs can contribute to a circular economy by utilizing hydrogen produced from various sources, including renewable energy and waste streams. For example, hydrogen can be generated from biogas produced from organic waste or from the electrolysis of water using excess renewable energy. This integration of HFCVs with circular economy principles can minimize waste, promote resource efficiency, and reduce the overall environmental impact of the transportation sector.
• Reduction of greenhouse gas emissions: HFCVs have the potential to significantly reduce greenhouse gas emissions in the transportation sector. As HFCVs produce zero tailpipe emissions, they can help mitigate climate change and improve air quality. When hydrogen is produced from renewable sources, the overall life cycle emissions associated with HFCVs can be close to zero, contributing to a more sustainable and low-carbon energy ecosystem.

However, the HFCVs have the potential to contribute to a sustainable energy ecosystem by integrating renewable energy sources, balancing the electrical grid, enabling decentralized power generation, promoting circular economy principles, and reducing greenhouse gas emissions. The versatility and flexibility of HFCVs make them a valuable component of a sustainable energy transition, offering cleaner and more efficient transportation options while promoting the integration of renewable energy into various sectors of the economy.

5. Current Challenges of HFCVs

The HFCVs are propelled by electric motors, but instead of being powered by a battery, like a conventional electric vehicle (EV), they generate electricity from a chemical reaction between hydrogen (stored on board in fuel tanks) and oxygen (from the air), facilitated by a device called a fuel cell. The only byproducts of this process are electricity, which is used to drive the vehicle, and water vapor, which is released into the environment, making HFCVs a zero-emission transportation solution.

However, while the prospect of a vehicle that emits nothing but water vapor is tantalizing, the path to the mass adoption of hydrogen FCVs is fraught with a variety of challenges as shown in Figure 7 and described in detail in this section.

• Infrastructure: One of the most significant challenges for HFCVs is the lack of a widespread hydrogen refueling infrastructure. Unlike gasoline stations, which are abundant in many areas, hydrogen refueling stations are relatively scarce and limited to certain regions. Establishing a comprehensive hydrogen infrastructure requires significant investments in the construction of new refueling stations, transportation, and storage facilities.
• Economic challenges: Currently, the costs associated with owning and operating an HFCVs are substantially higher than those for a conventional internal combustion engine vehicle or even a battery electric vehicle (BEV). High vehicle prices, largely due to the cost of the fuel cell systems, and expensive hydrogen fuel (resulting from the high costs of production, storage, and transportation) contribute to these economic barriers.
• Hydrogen production: The production of hydrogen for fuel cell vehicles poses challenges in terms of cost, energy efficiency, and environmental impact. The most common method of hydrogen production is through SMR, which relies on natural gas as a feedstock [76,77]. This process produces CO₂ emissions, which negate some of the environmental benefits of fuel cell vehicles. Developing and scaling up sustainable and low-carbon hydrogen production methods, such as electrolysis using renewable energy sources, is crucial but currently faces challenges in terms of cost and scalability.

  Table 2. Hydrogen production prices (2015–2022) [78,79].

  Year	Gray Hydrogen	Blue Hydrogen	Green Hydrogen	Turquoise Hydrogen	Brown Hydrogen	Purple Hydrogen
  2015	1.25	1.65	3	-	1.55	-
  2016	1.2	1.6	2.8	-	1.5	-
  2017	1.15	1.55	2.6	-	1.45	-
  2018	1.1	1.5	2.4	2.9	1.4	-
  2019	1.05	1.45	2.2	2.7	1.35	-
  2020	1	1.4	2	2.5	1.3	3.5
  2021	1	1.4	2	2.5	1.3	3.3
  2022	1	1.38	1.9	2.4	1.2	3.2

  shows the prices of hydrogen production.
• Energy efficiency: While fuel cell vehicles are more energy-efficient than traditional internal combustion engine vehicles, they are less efficient than battery electric vehicles. The energy required to produce, transport, and store hydrogen, as well as the energy losses in the fuel cell system itself, result in a lower overall energy efficiency compared with battery electric vehicles. Improving the energy efficiency of fuel cell systems and optimizing the entire hydrogen production and distribution process is essential.
• Safety concerns: Hydrogen, being a highly flammable gas, raises safety concerns related to storage, handling, and refueling. While HFCVs undergo rigorous safety testing and are equipped with multiple safety features, concerns remain regarding the potential for leaks, the behavior of hydrogen in various accident scenarios, and the infrastructure ability to handle emergencies. Ensuring strict safety standards and regulations, as well as public awareness, is crucial for addressing these concerns.
• Limited vehicle models and availability: Currently, the availability of HFCVs is limited, with only a handful of models on the market. The limited vehicle options make it challenging for consumers to find suitable choices that meet their preferences and requirements. Expanding the range of available vehicle models and increasing their availability in different regions are necessary to promote wider adoption.
• Competition from battery electric vehicles: Another major challenge for HFCVs comes from battery electric vehicles (BEVs). BEVs are currently ahead in the race for clean transportation. They benefit from better consumer awareness, more developed charging infrastructure, and rapidly improving battery technology, which has led to significant reductions in vehicle costs and improvements in driving range.

While hydrogen HFCVs hold great promise as a sustainable transportation solution, the challenges they face are significant. Addressing these challenges requires a collaborative effort from industry stakeholders, governments, research institutions, and infrastructure developers. Continued investment in research and development, improvement in production processes, expansion of refueling infrastructure, and supportive policies can help overcome these barriers and drive the widespread adoption of HFCVs as a clean and sustainable transportation option.

6. Current and Future Market Landscape

6.1. An Overview of the Current Market for HFCVs

The current market of HFCVs is still in its nascent stages but shows promising growth and potential. HFCVs represent an alternative to conventional internal combustion engine vehicles and battery electric vehicles, offering several advantages such as fast refueling, long driving ranges, and zero-emission operation.

Currently, the availability of HFCVs is limited, with a handful of models from manufacturers like Toyota, Hyundai, Honda, Mercedes-Benz, and Audi. These manufacturers have invested in research, development, and infrastructure to bring HFCVs to the market [80]. However, the production volumes of HFCVs are relatively low compared with other vehicle types, primarily due to factors such as high manufacturing costs, limited hydrogen refueling infrastructure, and the need for further technological advancements.

One of the significant challenges for the HFCV market is the establishment of a robust hydrogen infrastructure. Hydrogen refueling stations are still limited in number, which poses a barrier to widespread adoption. However, there have been efforts by governments, automakers, and energy companies to expand the hydrogen refueling network, particularly in regions where HFCVs are gaining traction. Infrastructure development is crucial for the growth of the HFCV market as it ensures convenient access to refueling stations and addresses range anxiety concerns. In terms of consumer acceptance, HFCVs currently face some challenges. The limited availability of models and infrastructure, coupled with higher upfront costs compared with conventional vehicles, can deter potential buyers [81]. However, HFCVs are gaining interest in specific markets and industries that require long driving ranges and quick refueling, such as commercial fleets, government agencies, and certain regions with a focus on hydrogen energy.

Looking to the future, the market landscape for HFCVs holds significant potential for growth. Several factors contribute to this positive outlook. First, ongoing advancements in fuel cell technology are making HFCVs more efficient, reliable, and cost-effective. Research and development efforts are focused on reducing the cost of fuel cell systems, improving durability, and increasing power density. These advancements will contribute to the commercial viability and affordability of HFCVs, making them more attractive to a broader range of consumers. Second, governments around the world are increasingly recognizing the importance of decarbonizing the transportation sector and reducing greenhouse gas emissions. As a result, they are implementing policies and providing incentives to promote the adoption of zero-emission vehicles, including HFCVs. These supportive measures can drive market growth, stimulate investment in infrastructure, and reduce the barriers to entry for manufacturers and consumers. Additionally, collaborations and partnerships between automakers, energy companies, and other stakeholders are playing a crucial role in the future of HFCVs. Joint efforts are focused on technology development, infrastructure expansion, and knowledge sharing, which can accelerate the adoption of HFCVs and create a positive feedback loop for market growth.

However, the current market landscape of HFCVs is still developing, with limited availability and infrastructure challenges. However, with ongoing advancements in fuel cell technology, supportive government policies, and collaborative efforts, the future for HFCVs looks promising. As costs decrease, infrastructure expands, and consumer awareness increases, HFCVs have the potential to become a viable and sustainable transportation option, contributing to the overall goal of decarbonizing the automotive industry and reducing dependence on fossil fuels.

Table 3. An overview of the current market for HFCVs [82,83].

Region	Number of Hydrogen FCVs (2022)	Market Share (2022)
North America	10,000	0.10%
Europe	8000	0.08%
Asia–Pacific	15,000	0.15%
Middle East	1500	0.01%
Rest of the world	2000	0.02%
Global	36,500	0.36%

shows an overview of the current market for HFCVs.

6.2. Recent Advancements in HFCVs

The recent advancements in HFCVs have focused on several key areas, aiming to enhance the performance, efficiency, durability, and cost-effectiveness. These advancements play a vital role in driving the adoption of HFCVs and expanding their market presence.

Table 4. The recent advancements in HFCVs [84].

Advancement	Description
Improved fuel cell stacks	Advancements in catalysts, membrane materials, and flow field designs leading to higher efficiency, durability, and cost reduction.
Cost reduction	Reduction in manufacturing costs through materials innovation, streamlined production processes, and economies of scale.
Extended driving range	Improved fuel cell efficiency and optimization of hydrogen storage systems to achieve longer driving ranges.
Cold-weather performance	Development of thermal management systems, freeze-resistant components, and advanced insulation materials to enhance performance in cold weather conditions.
Infrastructure development	Expansion of the hydrogen refueling network through collaboration between governments, energy companies, and automotive manufacturers.
Cross-sector collaborations	Collaborative efforts between automakers, energy companies, research institutions, and governments to share knowledge, conduct joint R&D, and establish standards and regulations.
Demonstration projects	Real-world testbeds for HFCV technology, providing valuable data and feedback for further improvements.
Commercial deployments	Implementation of HFCVs in sectors such as public transportation, logistics, and municipal fleets, demonstrating practicality and effectiveness.

shows the recent advancements in HFCVs.

These recent advancements collectively contribute to the maturation and growth of the HFCV market. They address key challenges such as the cost, range, performance, and infrastructure, making HFCVs more competitive with other zero-emission vehicle options. As advancements continue and economies of scale are achieved, it is expected that HFCVs will become even more efficient, cost-effective, and accessible to a wider range of consumers, driving the transition to a more sustainable transportation future.

7. Policies and Initiatives toward HFCVs

7.1. Companies’ Policies

The policies and strategies of automotive companies are subject to change as technology evolves and market dynamics shift. The concept policy toward the production of HFCVs is subjective and can depend on various factors, including technological advancement, environmental impact, market dynamics, and economic considerations. Moreover, there is a need for real-time data or the ability to evaluate these policies beyond the information available on the companies’ websites.

Table 5. The policy concepts of the companies for HFCVs [85,86].

Manufacturer	Current Stance	HFCV Model	Future Plans (as of 2025)
Toyota	Strongly supportive	Mirai	Continued development and refinement of HFCV technology, expansion of sales.
Hyundai	Strongly supportive	Nexo	Increase production of Nexo, further investment in fuel cell technology.
Honda	Supportive	Clarity Fuel Cell	Continue promotion of Clarity, although also focusing significantly on battery EV technology.
Mercedes-Benz	Cautiously supportive	GLC F-CELL	Focused on both HFCV and battery EV technology, with no specific future plans for HFCVs announced.
Audi	Skeptical	No specific HFCV model	As of 2021, Audi was primarily focusing on battery electric vehicles, with no specific plans for HFCVs announced.

shows the policy concepts of the companies (Toyota, Hyundai, Honda, Mercedes-Benz, and Audi) for HFCVs.

7.2. Government Policies

Government policies and initiatives play a vital role in promoting the adoption of HFCVs. Some of direction in which governments can and have been supporting the growth of this technology are as follows:

• Financial incentives: Governments can provide tax credits, grants, and subsidies to lower the purchase price of HFCVs, making them more competitive with conventional vehicles. For example, in the United States, the federal government provides a tax credit of up to USD 8000 for the purchase of a new fuel cell vehicle.
• Infrastructure development: Building out the hydrogen refueling infrastructure is a major challenge for the adoption of HFCVs. Governments can fund the development of this infrastructure through public–private partnerships, grants, or direct investment.
• Regulation and standards: Governments can also implement regulations and standards that encourage the use of HFCVs. This can include mandates for a certain percentage of new vehicle sales to be zero-emission vehicles or regulations to limit CO₂ emissions, effectively promoting cleaner alternatives like HFCVs.
• Research and development (R&D) funding: Government funding can boost R&D in HFCV technology, helping to improve the efficiency, reliability, and affordability of these vehicles. This can be done through grants, partnerships with universities, or direct investment in research projects.
• Public transportation and government fleets: Governments can lead by example by integrating HFCVs into public transportation fleets and government vehicle fleets. This can raise public awareness and acceptance of these vehicles, while also providing a reliable source of demand.
• Education and public awareness campaigns: Governments can support initiatives to educate the public about the benefits of HFCVs and dispel misconceptions. This can include public information campaigns, educational programs in schools, and community events.

In addition to these measures, the success of government policies in promoting HFCVs also depends on the alignment of these policies with broader energy, environmental, and economic strategies. An integrated approach that takes into account the entire hydrogen fuel cell ecosystem—from hydrogen production and distribution to vehicle manufacturing and end-user adoption—is likely to have the greatest impact.

8. Discussion

The transformational potential of HFCVs in shaping the future of sustainable transportation cannot be overstated. These vehicles stand out due to their noteworthy EER, higher power-to-weight ratio, and their capacity to dramatically reduce emissions. Yet, alongside these promising traits are significant challenges that cannot be overlooked when discussing the feasibility of their wide-scale implementation.

A primary concern is the high manufacturing costs associated with HFCVs. These costs make the vehicles less accessible to a wider consumer base, potentially stunting their spread and wider acceptance. Furthermore, the relatively low energy density of hydrogen compared with conventional fuels necessitates the need for larger storage units to achieve a comparable range, thereby complicating design and increasing vehicle weight. Safety concerns are another challenge that cannot be dismissed. The volatile nature of hydrogen, coupled with questions surrounding the durability of fuel cells, raises legitimate questions about the long-term viability and safety of HFCVs. However, the automotive industry has a long history of overcoming safety challenges through innovations in technology and design, suggesting that these concerns can potentially be mitigated in the future. The infrastructure needed to support a fleet of HFCVs on the roads today is also inadequate. The dearth of hydrogen refueling stations, combined with the complexities of hydrogen storage and transportation, poses significant challenges to the adoption of HFCVs. A collective commitment from both the public and the private sectors would be necessary to develop the infrastructure needed to support these vehicles. Despite these challenges, however, it is essential to underscore the remarkable opportunities that HFCVs present. The impressive EER and substantial emissions reduction potential, coupled with their fast-refueling capabilities, make HFCVs an attractive solution, particularly for long-range and heavy-duty transportation where battery electric vehicles may be less practical. When hydrogen is produced from renewable sources, HFCVs offer a truly green fuel alternative, providing another tool in our toolkit for mitigating climate change.

The roles of various stakeholders in advancing HFCVs cannot be understated. Prominent automakers such as Toyota, Hyundai, Honda, and Mercedes-Benz have shown a clear commitment to HFCVs, continuously developing and refining their models. Their efforts alone, though, are not enough. A broader transition to HFCVs requires more comprehensive initiatives, including public education campaigns, investments in hydrogen infrastructure, and continued research to improve the cost and performance of HFCVs. Governmental bodies also have a crucial part to play. By offering financial incentives, investing in infrastructure, establishing clear regulations and standards, and promoting public awareness, they can foster an environment conducive to the growth of HFCVs. HFCVs should be integrated into broader energy, environmental, and economic strategies to ensure alignment and maximize effectiveness. Furthermore, the future of HFCVs is tied intrinsically to the development of the hydrogen economy. As the global community moves toward renewable and sustainable energy solutions, hydrogen can play a significant role in balancing energy demands, enabling energy storage, and reducing carbon emissions.

While the pathway toward a broad HFCV adoption is lined with both technical and infrastructural challenges, the potential benefits it offers in our fight against climate change make these obstacles worth tackling. The critical components to achieving this goal are continued R&D, collaboration among various stakeholders, supportive government policies, and public acceptance. If sustained efforts are made, a hydrogen society where HFCVs are commonplace on our roads could very well be within our reach.

9. Conclusions

The HFCVs hold great promise for a sustainable and low-carbon future. They have distinct advantages such as zero tailpipe emissions, high energy efficiency, and the potential for fast refueling, making them a compelling solution for long-range and heavy-duty transport where battery electric vehicles may be less practical. Moreover, if produced from renewable sources, hydrogen can provide a truly green fuel option, further contributing to climate change mitigation efforts. However, the journey toward widespread adoption of HFCVs is fraught with challenges. Key among these are the high costs associated with vehicle production and hydrogen fuel cell technology, a lack of refueling infrastructure, and concerns about the efficiency and environmental footprint of hydrogen production. Despite these hurdles, advancements in technology, economies of scale, and significant R&D investments may likely help overcome these obstacles in the future.

The role of stakeholders in promoting HFCVs is crucial. Automakers, such as Toyota, Hyundai, Honda, and Mercedes-Benz, continue to develop and refine their HFCV models, highlighting a clear commitment to this technology. Nevertheless, a broader transition to HFCVs requires a more extensive set of initiatives and partnerships, including efforts to educate the public, develop hydrogen infrastructure, and invest in research to improve the cost and performance of HFCVs.

Government policies and initiatives also play a vital role in HFCV adoption. By providing financial incentives, investing in infrastructure, establishing clear regulations and standards, and promoting public awareness, governments can create an environment conducive to the growth of HFCVs. It is also critical for governments to integrate HFCVs into their broader energy, environmental, and economic strategies to ensure alignment and coherence.

The future of HFCVs is intricately linked with the overall growth of the hydrogen economy. As the world moves toward renewable and sustainable energy solutions, the hydrogen economy could play a significant role in balancing energy demands, enabling energy storage, and reducing carbon emissions. Therefore, strategies toward the promotion of HFCVs should be viewed not in isolation but as part of a broader push toward a sustainable and low-carbon future. While HFCVs present both opportunities and challenges, their potential contribution toward a sustainable, low-carbon future makes them an avenue worth pursuing. Continued R&D, collaboration among stakeholders, supportive government policies, and public acceptance are key to realizing the full potential of hydrogen fuel cell technology in the automotive sector. It is hoped that with sustained efforts, the vision of a hydrogen society where HFCVs are a common sight on our roads will become a reality.

10. Future Directions

As HFCVs are recognized as a potential key component of a low-carbon transportation future, both companies and governments can play significant roles in promoting their adoption.

Table 6. Recommendations for companies and governments toward HFCVs.

Recommendations	Companies	Governments
Invest in R&D	Allocate resources for R&D to advance fuel cell technology, improve efficiency, and reduce costs.	Provide funding and support for research initiatives to enhance HFCV technology and infrastructure.
Expand model lineup	Broaden the HFCV model lineup to include various vehicle types and sizes, catering to diverse consumer needs.	Encourage automakers to diversify their HFCV offerings and promote market competition.
Collaborate for infrastructure development	Collaborate with energy companies and governments to develop a comprehensive hydrogen refueling infrastructure.	Allocate resources and establish partnerships to expand the network of hydrogen refueling stations.
Promote consumer awareness and education	Invest in marketing and educational campaigns to raise awareness about the benefits of HFCVs and address misconceptions.	Implement awareness programs to educate consumers about the advantages of HFCVs and the transition to hydrogen.
Support hydrogen production and supply	Invest in the development of renewable hydrogen production methods to ensure a sustainable and low-carbon supply.	Establish policies and incentives to promote the production and availability of renewable hydrogen.
Foster international cooperation and standardization	Engage in international partnerships to share best practices, harmonize standards, and facilitate global adoption.	Participate in international forums to develop common standards and regulations for HFCVs and hydrogen infrastructure.
Establish supportive policies and incentives	Implement supportive policies, incentives, and subsidies to encourage HFCV adoption and reduce market barriers.	Establish financial incentives and regulatory frameworks to promote HFCVs, infrastructure development, and renewable hydrogen.

shows some future recommendations for companies and governments toward HFCVs.

These recommendations outline key areas of focus for both companies and governments to drive the growth and adoption of HFCVs. By implementing these recommendations, stakeholders can collectively accelerate R&D, expand market offerings, develop the necessary infrastructure, raise consumer awareness, support sustainable hydrogen production, promote international cooperation, and establish supportive policies and incentives for HFCVs.