Key aspects in the hydrogen fuel cell technology deployment

Although hydrogen fuel cells offer advantages in terms of performance and zero emissions, there are several factors that contribute to the relatively high cost of manufacturing and difficult the deployment of this technology compared to other propulsion solutions. Here are some key aspects that make hydrogen fuel cell manufacturing more expensive:

1. Materials and Components: Hydrogen cells themselves may seem relatively simple in their design, they use expensive materials, such as platinum or other catalysts, which are essential for electrochemical reactions. These materials add significant costs to the manufacturing process.
   
2. Scalability and Production Volume: Currently, the production of hydrogen cells has not achieved economies of scale comparable to those of other more mature technologies, such as internal combustion engines or batteries. Production at lower volumes may increase unit costs.

Cell Technology:

Fuel cell technology is relatively new and still under development. Innovation and constant improvement are essential to increase efficiency and reduce costs. However, research and development can be expensive and time-consuming.

• Hydrogen Infrastructure: The infrastructure necessary for the production, storage and distribution of hydrogen is expensive to establish. This includes hydrogen stations to fuel vehicles and investment in secure storage technologies.

• Manufacturing Processes: Hydrogen fuel cell manufacturing processes, especially those that involve the use of sensitive materials and specialized manufacturing techniques, can increase costs.

• Durability and Maintenance Guarantee: Hydrogen cells must be designed to operate for long periods with minimal maintenance. This can increase costs due to the need to ensure reliability and durability over time.

As hydrogen fuel cell technology evolves and becomes more widely adopted, costs can be expected to decrease due to innovation, improved manufacturing processes and maturing infrastructure. However, currently, the aforementioned aspects contribute to the relatively high cost of manufacturing and adopting hydrogen fuel cells.

Manufacturing hydrogen technologies and processes

Considering that the manufacturing of hydrogen cells is a new industrial sector with high growth potential, it is advisable to review the technologies and manufacturing processes that are associated, both to manufacture the individual components of the cell and to assemble them into a functional unit.

Here is an overview of the technologies required for hydrogen fuel cell manufacturing:

1. Electrodeposition: This technique consists into deposit uniform layers of materials on conductive substrates. In the context of hydrogen cells, it can be used to deposit catalysts, such as platinum, on the electrodes.
   
2. Cutting and Microfabrication: Hydrogen cell components, such as electrode plates and separators, often must be cut and manufactured to specific sizes and shapes. Laser cutting and microfabrication technologies are common in this process.
   
3. Electrode Printing: Some hydrogen fuel cells use printing techniques to apply layers of conductive ink containing the catalysts and electrode materials onto substrates.
   
4. Membrane and Electrode Assembly: Assembly of cell components, such as electrolyte membranes and electrodes, requires precision assembly techniques to ensure that all parts are correctly aligned.
   
5. Welding and Connections: Soldering and electrical connections are key aspects to ensure electrical conductivity throughout the cell. Welding and assembly techniques are used to connect the different components of the cell.
   
6. Membrane Coating: Electrolyte membranes are often coated with protective layers to improve their durability and performance.
   
7. Quality Control and Testing: The manufacturing of hydrogen cells involves rigorous quality control and testing to ensure that the batteries meet performance and safety standards. Testing may include electrical testing, leak testing and efficiency evaluation.
   
8. Subsystem Integration: In addition to the individual stack components, the integration of subsystems is also required, such as hydrogen supply systems, thermal management systems and control systems.
   
9. Automation and Robotics: Manufacturing hydrogen fuel cells often involves precise and repetitive processes. Automation is key to achieving efficiency and precision in production.
   
10. Recycling and Sustainability: Sustainable manufacturing of hydrogen fuel cells also involves consideration of the full life cycle of materials and components, including design for recycling and responsible management of the materials used. Regulation is increasingly intense in these aspects, so it is imperative to manage the risk that regulatory change implies.

It is important to note that the manufacturing of hydrogen cells continues to be an area of active research and development, and the technologies used are constantly evolving, so we can only make an approximation of the industrial parameters of this market.

Key Hydrogen Technology Development Area: Nanotechnology

It is important to consider that one of the research areas that can potentially transform the development and production of hydrogen fuel cells is in the field of materials engineering. Specifically, advances in nanotechnology can be the real technology drivers in this industry because of their ability to manipulate and control the structure and properties of materials at the nanoscale. Here are some ways in which nanotechnology can influence the manufacture of hydrogen fuel cells:

Advanced catalysts

Catalysts are essential in hydrogen fuel cells to speed up electrochemical reactions. Nanotechnology makes it possible to design and synthesize catalysts with nano-scale structures, which can increase the efficiency and speed of reactions in the battery.

Hydrogen Fuel Cells

Improved electrodes: Electrodes in hydrogen fuel cells can benefit from nanostructured materials that provide a larger surface area and better electrical conductivity. This can improve the efficiency of reactions in the cell.

Advanced Electrolyte Membranes: Electrolyte membranes used in hydrogen cells can improve their performance and durability through nanotechnology. Nanostructured structures can improve the ionic conductivity and selectivity of the membranes.

Sensors and Monitoring: Nanotechnology can enable the creation of nanostructured sensors that monitor real-time conditions within the stack, which can improve control and efficiency.

Protective Coatings: Nanostructured coatings can protect materials from corrosion and improve the durability of stack components.

Hydrogen Capture and Storage: Nanotechnology can play a role in the development of more efficient and safer hydrogen storage materials.

Component Integration: Nanotechnology can also influence how different components of the stack are integrated to maximize efficiency and durability.

In short, nanotechnology can provide tools and approaches that may significantly improve the efficiency, durability, and overall performance of hydrogen fuel cells. The ability to manipulate and control the structure of materials at the nanoscale opens up new possibilities for optimizing key battery components and advancing the technology.

Application to the development of AAM: Air Engines using hydrogen fuel cells.

One of the sectors where the development of hydrogen fuel cell technology has a fundamental effect is Advanced Air Mobility (AAM). In this context, we must focus on three technical aspects that determine the viability of the solution: Power, Weight, and Autonomy.

Power:

Of course, the power of an aero engine with hydrogen fuel cell technology depends on several factors, such as the design of the fuel cell, the efficiency of the propulsion system and the specific characteristics of the vehicle.

Generally speaking, hydrogen fuel cells have demonstrated the ability to provide sufficient power to propel aerial vehicles, including aircraft and drones. The exact details may vary depending on the application and the specific technology used in each case.

Weight:

Dealing with an aerial vehicle where weight is a fundamental parameter, it is necessary to consider the Energy Density aspect of the fuel. This measure allows us to compare the amount of energy that can be stored in different fuels, or energy sources. 

To assess the potential of this technology, we can do a small energy density analysis of Hydrogen, Kerosene and Batteries. A lower energy density means that the aircraft must carry more weight to transport the energy needed for flight.

• Energy Density of Hydrogen:
  
  Energy Density: Approximately 120-142 MJ/kg. Volumetric Density (at 700 bar): Approximately 5.6-6.9 MJ/l Energy Density of Kerosene (Jet Fuel):
  
  Energy Density: Approximately 43-47 MJ/kg  ii) Volumetric Density: Approximately 35-40 MJ/l
  
  Battery Energy Density (high range) (*)
  Lithium nickel manganese cobalt oxide (NMC) 0.6-0.8 MJ/kg ii) Volumetric Density: Approximately 0.7MJ/l

(*) Note: Some technology experts can foresee lithium-ion batteries’ energy densities doubling to 1.8 MJ/kg in the 2030’s, trebling to 2.7 MJ/kg by the 2040’s, and the best possible energy densities are around 4.5 MJ/kg.

As can be seen, hydrogen has a significantly higher energy density than kerosene, both in terms of energy per kilogram and energy per volume. However, the energy density of batteries is much lower (by almost two orders of magnitude).

Hydrogen Autonomy:

We have to consider that the variable autonomy is closely linked to power and weight. In this sense, for a given power, which will be determined by the TOW (Take Off Weight) derived from the market we want to reach with the aircraft, it is clear that the lower the weight of the propulsion-fuel system, the greater the range we will be able to achieve for a given payload.

With the above energy density numbers, it is clear to see why hydrogen is considered an attractive energy vector for advanced mobility applications, since with little weight, we can generate a lot of energy. 

However, this is not entirely true, as we must consider the additional weight of safe and efficient hydrogen storage and distribution. It is precisely this aspect that is the key challenge to be addressed in order to fully exploit its high energy density.

Navigating Hydrogen’s Energy Density Challenge in High-Pressure Storage for Aviation

To be precise, the actual energy density of hydrogen stored in high-pressure tanks must be considered. In this respect, it will be affected by the weight of the bottles and the storage system, which will reduce the amount of hydrogen that can be stored in a given space, and at a given weight.

It is important to note that high-pressure hydrogen storage in bottles can have a relatively low volumetric energy density compared to other methods, such as storage in liquid form or in solid absorbent materials. The space required to store hydrogen at high pressure can be significant and can affect the energy density in terms of energy per volume.

The exact impact on energy density depends on several factors, such as the pressure at which hydrogen is stored, the size and weight of the bottles, the storage capacity, and the type of storage system used. For example, if we consider a 700bar bottle made of carbon fiber, we would have a volume about 5 times larger than a jet fuel tank. 

As can be seen from the above data, hydrogen has a much lower density in terms of energy per volume compared to liquid fuels such as paraffin. 

High-pressure hydrogen storage is a practical solution for certain applications, but it is true that the larger volume required can be a limitation in some situations, especially compared to traditional liquid fuels. This is one of the reasons why other hydrogen storage technologies are being explored, such as cryogenic liquid storage and adsorbent solid materials, which can provide higher volumetric energy densities and reduce the need for such a large storage space.

(To be continued)