The Viability of Hydrogen as a Fuel Source for Transportation

Robert L. Boughner

Introduction

Carbon dioxide (CO₂) emissions due to the combustion of fossil fuels have created a growing climate change crisis. The world has seen a 1.1° C increase in surface temperature since 1900 and climate models predict up to 4.4° C by the end of the century¹. In order to meet energy demands with a reduction of fossil fuel combustion, alternative, sustainable energy sources are needed. Indeed, the USA has seen a decline in the percentage of energy from fossil fuels from 72.6% in 1985 to 59.1% in 2023² as gains in solar and wind energy have helped power the residential, industrial, and commercial sectors (see Figure 1).

Similar gains have not been seen in the transportation sector, which accounts for 31% of energy-related CO₂ emissions in the USA. As of 2022, fossil fuels still accounted for about 90% of the total transportation sector energy use³. While battery electric vehicles have seen growth, they present their own environmental challenges. For example, the mining of lithium, cobalt, and nickel for EV batteries contributes to habitat destruction and pollution. Also, battery-powered electric vehicles rely heavily on rare earth elements whose mining and processing can lead to radioactive waste, air and water pollution, and eutrophication of aquatic ecosystems⁴. Progress towards climate-friendly sources of energy is still needed in this sector.

One potential source of energy in the sector is hydrogen fuel cells (HFCs). In these engines, hydrogen gas is used to generate electricity to power the engine while water is released as emissions⁵. Hydrogen tanks can be stored on vehicles for quick refueling without the long charge times faced with battery-powered electric vehicles. This unit will focus on HFCs. How does the technology work? How is hydrogen obtained? And how do we overcome some of the challenges in the implementation of HFC as a dominant source of energy in transportation?

School Profile

I teach science courses at Memorial High School (MHS), a part of Tulsa Public Schools (TPS) in Tulsa, Oklahoma. TPS is the largest district in the state with 33,871 students. MHS has an enrollment of 1023 and is very ethnically diverse with 83% of students being minority: 34% Hispanic, 33% African American, 17% White, 8% Multiracial, 4% API, 4% Native American. A common feature at the school is poverty with 87% receiving free or reduced lunches. Only 10-14% of students show proficiency in math and/or reading. Utilizing diverse teaching strategies and learning activities is essential for achieving learning goals. This unit will seek to embed diverse learning activities into the lessons to maximize student engagement and provide scaffolding for students who often struggle with reading.

Rationale

This unit was developed for my AP Environmental Science (APES) class. It could easily be implemented in a standard Environmental Science course and could be modified for Physical Science. In APES, Unit 6 is dedicated to energy. In the unit, the “Enduring Understanding” is that “humans use energy from a variety of sources, resulting in positive and negative consequences”. It presents the demand for energy around the world and breaks down sources of energy, including fossil fuels, wind, solar, nuclear, and even hydrogen fuel cells. The course emphasizes the identification of environmental problems and potential solutions. One theme that I try to get across to my students is that there is rarely a simple solution to a problem as every issue involves multiple factors and perspectives that need to be considered. Once you understand the nuances, you can make more informed, thoughtful decisions. Climate change from CO₂ emissions is a problem that must be acted upon. Reducing emissions requires a movement away from petroleum as our main energy source, but we must identify environmental-friendly renewable energy sources to meet the energy demand of the world. For many of our energy needs, APES identifies the potential of solar and wind in producing electricity. Students see the wind farms in Oklahoma and, indeed, 42% of electricity here comes from wind⁶. For transportation, however, there is a gap in the curriculum. While HFCs are considered, I feel that the course needs depth on the topic. Students may recognize that it is a neat technology, but can hydrogen replace petroleum in our cars, trucks, and airplanes?

This seminar will allow me to build a unit in which students have to deeply consider the technology of electricity generation with hydrogen as the fuel. Moreover, students must identify the practical difficulties in implementing wide-spread use of hydrogen fuel cell technology.

The goals of the unit will be to:

1. Analyze the technology behind HFCs that allow the fuel to generate electricity in engines.
2. Identify the challenges of generating and collecting hydrogen gas in a sustainable, environmentally friendly manner.
3. Explore the viability of developing a network for hydrogen fuel distribution; where will consumers purchase the gas?

Unit Content

Part 1: The Technology of HFCs

HFCs produce electricity by converting the chemical energy of H₂ gas into electrical energy through an electrochemical process.⁷ While there are several different types of technologies for hydrogen fuel cells, perhaps the most promising is the proton exchange membrane fuel cell (PEMFC)⁸. Figure 2 shows the schematic for a PEMFC stack.

The PEMFC stack operates by splitting hydrogen gas (H₂) at the anode, where a catalyst, typically composed of platinum nanoparticles, lowers the activation energy needed for the reaction⁹. A carbon or graphene-based support material is used to disperse the platinum particles. This hydrogen oxidation reaction has the hydrogen molecules dissociate into protons (H⁺) and electrons (e⁻), and the protons move across the polymer membrane. A polymer membrane made of perfluorosulfonic acid is considered ideal as it provides high ionic conductivity at low to moderate temperatures (60°–80°C)¹⁰. Meanwhile, the electrons travel through an external circuit, generating an electric current. At the cathode, an oxidation-reduction reaction occurs where oxygen (O₂) reacts with the transported protons and electrons in the presence of a platinum catalyst, forming water (H₂O) as the only byproduct. The electric current from the external circuit powers the automobile’s motor.

Automobiles running on an HFC have significant advantages over internal combustion engines (IC; gasoline, diesel, etc.) and even battery-powered electric vehicles. The most obvious advantage of hydrogen fuel cells is their zero emissions. In contrast, CO₂ emissions from fossil fuel combustion have significantly impacted the planet, contributing to rising global temperatures that threaten life. While a full analysis of climate change is beyond the scope of this unit, see IPCC (2021) for a detailed overview¹¹. IC engines also emit CO, SOx, NOx, and particulate matter. These pollutants have serious health consequences. A model by Lelieveld et al. (2019) estimates that phasing out fossil fuels could prevent 3.61 million air pollution-related deaths worldwide each year.¹² It is hard to overstate the advantages of a clean source of energy.

HFCs have a number of other advantages over IC engines, including better fuel efficiency. Currently, HFCs have efficiencies of approximately 45.9%, compared to the 23.2–29% efficiency range of IC engines¹³. This means that for the same amount of energy input, HFC-powered vehicles convert nearly twice as much energy into usable power; IC engines lose a significant portion of their energy as heat. As a result, fuel cell vehicles require less fuel per mile traveled, reducing both energy consumption and operating costs over time. HFC cars are also quieter (similar to battery-powered electric vehicles) and have less vibration than IC engines. Additionally, HFC cars require significantly less maintenance. There are no oil changes needed or other maintenance. The fuel cells degrade over time (lifespan of about 7300 hours), but at a rate similar to IC engines¹⁴.

HFC technology is not without disadvantages. HFCs are costly to make. The catalyst at both the cathode and anode requires platinum nanoparticles to lower the activation necessary for the electrochemical reaction, and platinum is expensive and nonrenewable. This has made mass production of HFC vehicles difficult. As of 2025, there are two HFC models available in the United States: the Toyota Mirai and the Hyundai Nexo (see Figures 3a and 3b). The 2025 Toyota Mirai had a starting MSRP at $52,000 compared to the comparable gasoline 2024 Toyota Camry that started at $28,700.

One way to lower costs of HFCs is to find a substitute for the platinum catalyst needed at both the anode and cathode as the platinum contributes 45% of the cost to the stack¹⁵. Scientists have been exploring alternative materials for the catalyst needed to produce the hydrogen oxidation reaction (HOR) at the anode and the oxygen reduction reaction (ORR) needed at the cathode. Chandran et al. (2018) developed a platinum-free catalyst composed of a palladium-cobalt (Pd-Co) alloy supported on nitrogen-doped graphene. The catalyst showed excellent performance in both the HOR at the anode and ORR at the cathode. Other researchers have explored an iron-nitrogen-carbon (Fe-N-C) material created in various ways for catalyzing the ORR and have shown strong results^{16, 17, 18}. Other materials have been developed for catalyzing the HOR at the anode. A Ru₇Ni₃/C based cathode has shown promising results, and the cost is 85% less than platinum based ones¹⁹. Other researchers have explored palladium-based²⁰ materials. The research into platinum-free catalysts shows that the cost of making HFCs could be significantly reduced in the future.

Another potential problem with HFC technology is that the platinum-based catalysts are very sensitive to carbon monoxide (CO). Even small amounts of CO can poison the catalyst and significantly reduce efficiency²¹. The introduction of CO into the system can come from impure H₂ gas that is created from the steam reforming of methane method. One potential solution to this problem is to not use methane to make H₂ (see next section). Another possibility is to use platinum-free catalysts, which show less sensitivity to CO.

Part 2: Obtaining Hydrogen

Hydrogen is the most abundant element in the universe. While the element can be seen bonded in compounds like water and hydrocarbons here on earth, H₂ gas is rarely observed in natural settings. To obtain hydrogen fuel, specific processes are needed to generate the gas. Currently, about 95% of H₂ in the United States is obtained from methane (CH₄) through a process known as Steam Methane Reforming (SMR)²². In this, CH₄ is heated along with water at 700^◦ – 1000^◦ C along with a catalyst (usually nickel based)²³. Additional CH₄ is typically combusted to provide the heat for the reaction. The H₂ gas separates from the carbon and CO and CO₂ is produced as a biproduct. The H₂ obtained from this method is often called “gray” hydrogen, and a similar process of coal gasification produces “brown” hydrogen. There are clear advantages to using CH₄ as a source of H₂. It is widely available, relatively inexpensive, and it has a high hydrogen content with each molecule containing four hydrogen atoms. While the use of H₂ in HFCs does not produce CO₂, these processes of creating H₂ produce large amounts. This undermines one of the major goals of using HFCs in the first place. If we are to reduce greenhouse gas emissions in the transportation sector, a more environmentally friendly method of obtaining H₂ is required. In the scientific literature, a labeling system has emerged that uses colors to refer to how the H₂ is produced (see Table 1).²⁴

Table 1. The Colors of Hydrogen

Color	Source of Energy	Source of Hydrogen	Production Process	CO₂ Emissions
Green	Renewable energy	Water	Electrolysis	No direct CO₂ emissions
Orange	Mix of electricity grid	Various	Electrolysis	Depends on the electricity mix
Pink	Nuclear	Water	Electrolysis	No direct CO₂ emissions
Red	Nuclear	Water	Thermolysis/Thermochemical process	No direct CO₂ emissions
Yellow	Solar	Water	Electrolysis	No direct CO₂ emissions
Gray	Non-renewable energy	Natural gas	Steam Methane Reforming	High
Blue	Natural gas/Biomass	Natural gas	Steam Methane Reforming with Carbon Capture and Storage	Low
Turquoise	Natural gas	Natural gas	Pyrolysis	No direct CO₂ emissions
Brown	Lignite coal/Biomass	Coal	Gasification	High
Black	Bituminous coal	Coal	Gasification	High

As the table shows, hydrogen can be obtained in a number of different ways with different energy sources, sources of hydrogen, and production processes. Each technique varies in their CO₂ emissions and cost effectiveness. As mentioned previously, gray is by far the most commonly used technique right now, but perhaps the two most promising techniques in the future will be green and turquoise.

In turquoise hydrogen, methane is used to generate hydrogen but using a different technique than in gray hydrogen. Methane is heated to 800-1000° C in a process called pyrolysis²⁵. CH₄ decomposes into 4 H atoms and solid carbon (C) instead of CO₂. The C is a solid called carbon-black that can be collected and used for pigment (e.g., printer toner), rubber production, and battery manufacturing²⁶.

Green hydrogen can be obtained through electrolysis of water. In this, a current is passed through water, and the H₂O bonds split to form H₂ and O₂, the opposite process that is used in HFCs²⁷. There are no CO₂ emissions, but energy is required to create a current. If the energy is created with fossil fuel combustion, CO₂ emissions are still there, of course, but the end goal for green hydrogen is to use renewable energy sources for the electrolysis process. Wind, solar, hydroelectric, geothermal, or other forms of green energy would be used to generate the electric current necessary for electrolysis. With this setup, there are no emissions produced to generate the hydrogen and no emissions in using it to fuel the automobiles.

Part 3: The Logistics of Hydrogen Fuel Use

One of the challenges of moving away from petroleum in automobiles is, how will the fuel be obtained? For gasoline-powered engines right now, there are already many advantages in place. Petroleum is a liquid that is easy to transport. There is already an infrastructure built: pipelines carry fuel to refineries, a distribution network is in place for transporting petroleum around the country, and gas stations are readily available. The fuel is easy to transfer to the vehicle; just pump it into the tank. Petroleum is also relatively safe and stable.

While battery-powered electric vehicles have some similarities to HFCs (e.g., lower emissions), they have infrastructure challenges. A charging station is required, and while they are becoming more wide-spread, significant amount of time is needed to charge. Even with more modern technology in charging stations (e.g., Direct current fast charging), a battery-powered electric vehicle can take up to an hour to fully charge²⁸. For drivers on road trips, this can be prohibitive. An advantage of electric cars powered by HFCs is that refueling can happen very quickly. Theoretically, a H₂ tank could be filled in the time it takes to fill an automobile with gasoline.

HFC vehicles currently face challenges related to the production, transportation, and availability of hydrogen gas. First, H₂ has a relatively low energy density by volume. This means that distributing it in its gas form does not make practical sense as a truck load of H₂ tanks would hold relatively small amounts of the gas. Similarly, the fuel tank of a HFC car would have to be substantially large to have any range at all.  Instead, two options are available: cryogenic and compression storage. In cryogenic storage, the gas must be cooled to below -253^◦ C, the boiling point of the gas, to get it into a liquid form²⁹. This requires a cooling system and specialized insulated tanks for transport, and even in liquid form, the gas is not as energy dense as gasoline (8.5 MJ/L for H₂ vs 34.2 MJ/L for gasoline). In compression storage, the H₂ gas is compressed and stored at 1,000 psi (700 bar; it is compressed such that 700 liters of H₂ is compressed into 1 L). This allows for a much larger storage capacity, making it the overwhelmingly preferred method in 2025.

H₂ gas also suffers from significant transportation challenges compared to fossil fuels. Natural gas, for example, benefits from extensive pipeline networks that transport large volumes efficiently and cost-effectively. H₂ does not have these networks yet. Currently, about 1,600 miles of H₂ pipeline exists, mainly in the Gulf Coast region³⁰. Increasing this network requires a high initial capital cost that makes implementation difficult. It is possible to use existing natural gas pipes, but not without substantial modification. H₂ has substantially different physical and chemical properties than natural gas. H₂ can cause embrittlement of the steel, leading to degradation of the pipeline. In addition, the small nature of the molecule makes it susceptible to leaking. H₂ is highly combustible, causing significant safety concerns. The natural gas pipelines would have to be retrofitted for H₂ use. The solution that seems most appropriate in the long-term is to insert a new, non-reactive inner pipe within the existing pipeline to serve as a barrier against hydrogen interaction with steel³¹. Once again, this carries a significant upfront cost.

Some researchers have proposed utilizing ammonia (NH₃) as a means of transporting H₂³².  Like CH₄, ammonia has a high hydrogen count. It is one of the most produced substances in the world and is primarily used as fertilizer for agriculture.  The primary industrial method for making ammonia is the Haber-Bosch process in which atmospheric nitrogen (N₂) is converted into NH₃ with the addition of H₂, an iron catalyst, various promoter materials, and high heat and pressure³³.  While energy is needed to make ammonia, it is possible to do so with green energy; the product is called green ammonia. There are tremendous benefits to transporting ammonia rather than H₂. It is easily liquified with low pressure and transported easily. There is already a large infrastructure (pipelines, tankers, and storage systems) established for transporting and distributing ammonia globally. Ammonia is also much safer to transport; it is less prone to leakage and explosions. Once ammonia has been transported to a hydrogen production facility, H₂ can be extracted by a process known as ammonia decomposition. In this, NH₃ is “cracked” with high temperature and a nickel catalyst³⁴. While more energy is required to create and transport H₂ in this way, the existing infrastructure and ease of transport make it feasible.

The cost of H₂ gas is currently prohibitive for many consumers; buying H₂ instead of gasoline is just more expensive. Currently, H₂ costs about 2-3 times more per mile than gasoline. The price of H₂ in 2025 is about $12-$16 per kg. One kg of H₂ has the energy equivalence of one mile of gasoline, which sits at around $3-$4 per gallon. As an example, if the Toyota Mirai were to travel 200 miles, it would cost between $65 and $80. An equivalent gas-powered car (Toyota Camry) could travel 200 miles for $21-$24. To offset this, Toyota and Hyundai are both currently offering free H₂ for up to 6 years or $15,000, whichever comes first with the purchase of a Mirai or Nexo in California. Why is the cost of hydrogen so high? Many of the reasons have been discussed previously; there is a lack of infrastructure for transporting H₂ and the gas has a lower energy density. Creating H₂ is also costly as it requires significant energy. Even for gray hydrogen, the cost to create H₂ is expensive. A shift to green hydrogen as the energy source would add an even larger price tag.

A final limitation is that there is very limited hydrogen refueling infrastructure. While gas stations are everywhere for petroleum products, a similar infrastructure does not exist for H₂. There are currently only 54 H₂ stations in the USA that are open to the public, all of which are in California³⁵. As a result, HFC cars are only available to purchase from retail in California.

Considering all of the potential drawbacks to using HFCs, it is easy to see why they have not been implemented more broadly, despite such powerful positive attributes. Can these negatives be overcome? I believe that there is a viable pathway for widespread implementation. It requires technological innovations to increase H₂ production, a widespread implementation of HFC technology, and economic changes to make H₂ and HFCs more affordable. For HFC use to make sense from an ecological perspective, we must move away from gray hydrogen produced by steam methane reforming and embrace green hydrogen. For this to happen, the entire green energy sector needs to advance. Increased energy production from solar, wind, and other green renewable energy would reduce the cost necessary to make green hydrogen. In turn, the cost of H₂ gas would decrease as well. The future of HFCs is largely dependent on the future of green energy.

The cost of the HFC fuel stacks must be reduced. The platinum needed to catalyze reactions at the anode and cathode contribute significantly to the overall cost of the HFC vehicles. Finding inexpensive alternatives that are equally effective is needed and promising results have been shown with palladium and Iron-Nitrogen-Carbon catalysts. This would reduce fuel cell cost considerably.

The cost to purchase H₂ gas must be reduced. This can be achieved through several possibilities. First, an investment in infrastructure to transport H₂ is needed. To be economically feasible, demand must increase, but this becomes a bit of a chicken-egg problem. Some of this can be eased with policy. Increased subsidies for H₂ can help to offset the initial high capital costs of pipeline investments, transportation infrastructure, etc. As the infrastructure is built, the cost is lowered which further incentivizes adoption of HFC automobiles. Implementing HFCs for public transport can aid in the implementation.

A second approach to lowering H₂ gas prices is particularly appealing. Instead of building a large infrastructure for pipelines, trucking routes, etc., rely on localized H₂ production at the site where H₂ will be dispensed. Minutillo et al (2021). documented how such a facility would be designed ³⁵ (see Figure 4)

In such a setup, H₂ would be generated, compressed, and dispensed at a single location. Green energy from photovoltaic cells (or other sources, depending on availability in the area) is used to provide the power necessary to perform electrolysis and generate H₂, and the gas is captured and compressed. Compression generates heat, so the H₂ would then be sent to a cooling system. From there, the fuel can be sent to a storage tank where it can be directly dispensed to HFC vehicles. This integrated approach eliminates many of the challenges associated with hydrogen transport and reduces overall fuel costs. Building these stations still requires significant initial capital. Policy makers can support the process by providing funding and subsidies to help offset the costs.

The challenge of implementing HFC vehicles on a large scale is undeniable, especially when using green hydrogen. That said, the stakes could not be higher. CO₂ emissions from fossil fuels are producing a climate crisis that poses an unprecedented threat to global ecosystems and human livelihoods. To mitigate this crisis, we must transition from fossil fuels to cleaner energy solutions. HFC technology using green hydrogen presents a promising pathway, particularly in the transportation sector. If we embrace HFCs and push innovation of the technological advances needed, we can begin to reduce emissions. It will require a commitment to building infrastructure networks, lower costs, advance policy and regulatory measures, and generally an embrace of green energy as a whole. If successful, we can begin to solve the climate crisis while still meeting our energy needs.

Teaching Strategies

Model Building

To understand complex systems like a HFC fuel stack, an excellent learning approach is for students to build a model of the complex system. Using classroom supplies, students construct components, arrange them in a logical sequence, and visualize how each component interacts with the overall system. This style of hands-on learning helps reinforce conceptual understanding of the system as a whole while also encouraging critical thinking about the function and interaction of each component. Additionally, students enjoy these styles of activities and the creativity necessary for completion, and it encourages them to connect engineering concepts with real-world applications.

Lab Activities

APES is a lab science course. In fact, AP specifies that 25% of instructional time should be spent on hands-on, inquiry-based laboratory activities and investigations. This unit on HFC vehicles fits well within this framework. Students can gain valuable scientific skills by performing labs about HFC in an experimental setting.

Group Project and Posters

Group research projects allow students to develop problem-solving skills to explore real-world problems and offer potential solutions. This approach encourages students to conduct their own research, synthesize diverse ideas (even conflicting ones), and effectively communicate their findings. The projects require students to work collaboratively to develop teamwork skills that distribute the workload equitably while ensuring that students work together to produce a final product. In order to aid in organization, group roles will be assigned, and a clear rubric will guide students in understanding the assessment criteria. Group projects are particularly effective for complex topics, such as proposing policies and strategies related to hydrogen infrastructure and implementation.

Class Activities

Hydrolysis Lab

An important component for overall comprehension of the unit is for students to understand how H₂ can be produced via electrolysis. To aid in this, a hands-on lab will be conducted such that students will be able to create H₂ gas using lab supplies, and experiment with different sources of energy.

Equipment for each lab group:

• A plastic cup
• 200 ml of water
• 1 tsp of Sodium Sulfate
• Drops of Universal Indicator
• Two nickel-plated nails, 1.5 inches (the cathode and anode)
• 9 V battery
• 6 V battery
• 1 AA battery
• 1 Solar panel
• Alligator clips
• 1 Multimeter

Setup: The two nickel-plated nails will be poked into the bottom of the plastic cup. They can be secured with a glue gun to prevent any water from leaking. Water is poured into the cup and the sodium sulfate is dissolved. Several drops of universal indicator are then added. Alligator clips are attached to the bottom of the nails, and they are then attached to an energy source.

Experiments: The independent variable in the experiment will be the energy source. Students will attach each one via alligator clips to the electrodes. When connected, hydrogen bubbles will form at the cathode and oxygen bubbles will form at the anode. Students will make observations, and the dependent measure is the number of hydrogen bubbles. Student lab groups will measure this using the 9 V battery, a 6 V battery, a AA battery (1.5V), and the solar panel. Students will also use a multimeter to measure the current produced by each energy source. Once observations and the data have been recorded, students will be required to write a lab report detailing their observations, interpret the data, and make graphical representations.

Simulation and Fuel Stack Model

In order to help foster understanding of the technology of HFCs, students will build a model fuel stack; a visual and interactive representation of how HFCs work. To help them understand the overall system, students will first complete a simulation activity that demonstrates the interactions of the components of the fuel stack.  The Lawrence Hall of Science at Berkely has created an excellent simulation of the HFC fuel stack³⁶. Students can use the simulation to help guide the construction of their model.

Students will work in groups of 2 or 3, and they must create a model using the following supplies:

Supplies:

• Modeling clay
• Aluminum foil
• Cardboard
• Electrical wire
• Popsicle sticks
• Vinyl tubing
• Tape

Groups have flexibility as to which supplies they use to build the fuel stack, but they must have the following components:

• H₂ intake
• Anode
• Proton-exchange membrane
• Cathode
• Electrical circuit
• O₂ intake
• H₂O emissions

By engaging in both the simulation and the model-building activity, students will gain a deeper understanding of exactly how the HFC fuel stack works. This hands-on approach reinforces the theoretical concepts of the HFC design, and it encourages students to think creatively about sustainable energy solutions, making the learning experience both meaningful and relevant. It very much connects to APES themes: students analyze energy sources, efficiency, and sustainability in real-world contexts.

Hydrogen Implementation Project

In this project, students will explore potential policy changes necessary to implement HFCs on a large scale. Students will be broken into 4 groups. They will conduct research on different aspects of HFC implementation and give a presentation to the class.

Groups will work to discuss their findings and develop a policy proposal addressing the following key areas:

1. Production policy: What incentives can be given to advance green hydrogen? How might funding be provided for the research and development needed for the advancement of efficient electrolysis technology? How might funding be provided for the development of lower cost catalysts and other components of the fuel stack?
2. Infrastructure policy: How might funding be provided for the construction of hydrogen fueling stations around the country? Can networks be built for transporting H₂? Is it viable to construct onsite H₂ production and dispensing stations?
3. Economic policy: How might HFC vehicles be made more affordable through subsidies? Can carbon credits or other economic systems be provided for companies that adopt hydrogen technology? How might companies be encouraged to invest in hydrogen infrastructure?
4. Environmental policy: What would be needed to move away from gray hydrogen? How might non-renewable hydrogen production be regulated? What policies might encourage the use of green energy in the production of hydrogen?

Students will read about potential solutions to the problems posed in their group. They must apply critical thinking in producing potential solutions to some significant problems. Students will then create and deliver a 10–15-minute presentation on their work. They may choose to use visual tools like slide decks or create a poster presentation to effectively showcase their proposals.

Appendix: Science Standards

AP Environmental Science – ENDURING UNDERSTANDING

 ENG-3 Humans use energy from a variety of sources, resulting in positive and negative consequences.

AP Environmental Science – BIG IDEAS

BIG IDEA 1: ENERGY TRANSFER (ENG)

Energy conversions underlie all ecological processes. Energy cannot be created; it must come from somewhere. As energy flows through systems, at each step, more of it becomes unusable.

BIG IDEA 3: INTERACTIONS BETWEEN DIFFERENT SPECIES AND THE ENVIRONMENT (EIN)

Humans alter natural systems and have had an impact on the environment for millions of years. Technology and population growth have enabled humans to increase both the rate and scale of their impact on the environment.

BIG IDEA 4: SUSTAINABILITY (STB)

Human survival depends on developing practices that will achieve sustainable systems. A suitable combination of conservation and development is required. The management of resources is essential. Understanding the role of cultural, social, and economic factors is vital to the development of solutions.

AP Environmental Science – SKILLS:

Explain environmental concepts, processes, or models in applied contexts.

AP Environmental Science – ESSENTIAL KNOWLEDGE

ENG-3.P.1 Hydrogen fuel cells are an alternate to nonrenewable fuel sources. They use hydrogen as fuel, combining the hydrogen and oxygen in the air to form water and release energy (electricity) in the process. Water is the product (emission) of a fuel cell.

ENG-3.Q.1 Hydrogen fuel cells have low environmental impact and produce no carbon dioxide when the hydrogen is produced from water. However, the technology is expensive and energy is still needed to create the hydrogen gas used in the fuel cell.

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Notes

¹ IPCC, 2021
² Ember, 2024
³ U.S. Energy Information Administration, 2025
⁴ Zapp et al., 2022
⁵ Monoharan et al., 2019
⁶ U.S. Energy Information Administration, 2021
⁷ Fan, Tu, & Chan, 2021
⁸ Tellez-Crus et al., 2021
⁹ Wang et al., 2022
¹⁰ Lee et al., 2020
¹¹ IPCC, 2021
¹² Lelieveld, et al., 2019
¹³ Durkin et al., 2024
¹⁴ Kurtz et al., 2019
¹⁵ Chandran et al., 2018
¹⁶ Yin et al., 2024
¹⁷ Chen et al., 2021
¹⁸ Liu et al., 2022
¹⁹ Xue et al., 2020
²⁰ Zhang et al., 2016
²¹ Wang et al., 2010
²² US Department of Energy, 2025
²³ Simpson and Lutz, 2007
²⁴ Incer-Valverde et al., 2023
²⁵ Diab et al., 2022
²⁶ Khodabakhshi et al., 2020
²⁷ Mei, Sun, and Zhao, 2024
²⁸ US Department of Transportation, 2025
²⁹ Faye, et al., 2022
³⁰ US Department of Energy, 2025
³¹ Telessy et al., 2024
³² Lucentini et al., 2021
³³ Humphreys et al., 2020
³⁴ Lamb et al., 2019
³⁵ US Department of Energy, 2025
³⁶ Minutillo et al., 2021
³⁷ Lawrence Hall of Science, 2025