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Overcoming challenges in mechanical projects in the hydrogen area

20 November 2023
Article by Luís Esteves, product development engineer at INEGI, originally published in the 9th edition of H2 Magazine.

Hydrogen, often considered the fuel of the future, has immense potential as a clean and efficient energy source. With the increasing focus on decarbonization and sustainable solutions, mechanical projects in the hydrogen space have received significant attention in recent years.

However, working with hydrogen comes with a unique set of challenges that engineers and product developers must address to ensure safe and reliable operation. In this article, we expose some of the difficulties we face associated with mechanical projects in the hydrogen area and analyze the measures adopted to overcome them.

1. Transport and Storage
The highly flammable nature of hydrogen requires meticulous transportation and storage practices. The gas is light, odorless and colorless, making it difficult to detect during leaks. Furthermore, hydrogen molecules have a tendency to diffuse into metals, increasing the risk of leaks over time. As engineers, we face the challenge of designing robust storage systems that minimize leaks while ensuring safety. Innovative solutions, such as advanced composite materials, reinforced or surface-coated storage tanks, and comprehensive continuous leak detection systems, are some of the methods employed to mitigate these risks.

2. Infrastructure Development 
Implementing mechanical projects in the hydrogen area requires a support infrastructure, including production, transportation and fueling or refueling facilities. Establishing an extensive hydrogen infrastructure represents a significant challenge due to high costs, limited production capacity and the need for specialized equipment. Developing a comprehensive network of fueling stations for hydrogen-powered vehicles, for example, is a complex task that involves collaboration between stakeholders, including government bodies, energy companies and car manufacturers.

3. Energy Efficiency and Conversion
Efficiently harnessing the energy stored in hydrogen is another obstacle that we as engineers face. Although hydrogen fuel cells offer reasonable energy conversion efficiency, the overall efficiency of the system can be compromised by factors such as heat losses, electrical losses and limitations in catalyst performance. Overcoming these challenges requires continued research and development efforts to improve the efficiency of hydrogen fuel cells, electrolyzers and other conversion technologies.

4. Security Measures
Safety is of utmost importance in any mechanical project in the hydrogen field. The explosive nature of hydrogen requires strict safety measures throughout the project lifecycle. Implementing adequate ventilation systems, gas sensors and safety protocols is essential to prevent accidents. Furthermore, as engineers we must consider the potential risks associated with hydrogen leaks, combustion and possible ignition sources. Extensive testing, risk assessments and adherence to safety standards are critical to ensuring the safe operation of systems that handle hydrogen.

5. Cost and Scalability
The cost of hydrogen production, storage and infrastructure development remains a significant challenge. Although technological advances and economies of scale are reducing costs, hydrogen projects still face competitiveness challenges in relation to conventional energy sources. Achieving scalability is essential to reduce production costs, attract investment and make hydrogen solutions more economically viable in various industries. To respond to each of these five vertical pillars, we identified some lines of action transversal to these, such as the selection of materials and the selection of safety mechanisms, as they are present in practically all phases of development and must be taken into consideration in the different phases of the project.

6. Material Selection
Material selection is one of the most critical factors to address in the initial phases of product development and mechanical design, both in the development of customized equipment and in the selection of standard equipment, such as valves and accessories.

As hydrogen is a molecule with a diameter of approximately 120 pm, this means that gas diffusion phenomena in materials have to be taken into consideration due to the problems that may arise from this. Mainly with regard to one of the most used materials in the construction of equipment for industry, from carbon steel and, depending on the service temperature, we can observe the phenomenon of hydrogen embrittlement at room temperature and, at high temperatures, the phenomenon of hydrogen attack. Both phenomena promote a reduction in the resistance and ductility of the material since the carbon atoms that diffuse towards the interior, close to the grain boundaries, react with the free carbon present there, often coming from carbides, giving rise to carbon molecules. methane (CH4), with a diameter of 380 pm (three times larger than hydrogen) promoting an increase in tensions at the grain boundaries and promoting the appearance of cracks within the material's structure.

In low carbon alloys, elements such as chromium, nickel, molybdenum, tungsten and vanadium must be looked for, however their quantity in the alloy must be taken care of since high concentrations of chromium, for example, could lead to reduction of ductility in the presence of hydrogen. In order to minimize the reaction of hydrogen with carbon on the surface and future diffusion into the material, applications of surface coatings are emerging that aim to reduce the permeability of hydrogen into the microstructure, emerging in the scientific community and industry. the research topic Hydrogen Protection Barriers - HPB or protective barriers for hydrogen, in which oxides, carbides and nitrides are used to form these layers.

Another focus that the industry has followed in this new era is the use of polymeric composite materials in which the diffusion of hydrogen in these materials is quite low, which are subsequently reinforced with carbon fibers, for example, so that they can be used in the ranges service requirements of hydrogen technologies.

7. Selection of Security Mechanisms
Hydrogen systems generally utilize several safety mechanisms to mitigate the risks associated with the use and handling of hydrogen. For information purposes, we mention the most common security mechanisms and the aspects to take into account when selecting them:
  • Pressure Relief Devices: Hydrogen systems are equipped with pressure relief devices, such as pressure relief valves or rupture discs. These devices are the most common devices and release gas in a controlled manner if the pressure in the system exceeds safety limits, preventing the build-up of excessive pressure.
  • Hydrogen Sensors: Hydrogen sensors are used to detect the presence of the gas in the surrounding environment. These can be connected to alarms or activate active safety protocols when the hydrogen concentration exceeds a predetermined limit, indicating a possible leak.
  • Ventilation Systems: Proper ventilation is crucial for hydrogen systems in order to prevent gas accumulation in confined spaces. Ventilation systems, such as fans or exhaust systems, ensure continuous air exchange, reducing the risk of hydrogen accumulation and minimizing the formation of explosive mixtures.
  • Flame and Explosion Detection Systems: To detect the presence of flames or explosions, hydrogen systems can incorporate specialized detectors. These detectors monitor the environment for characteristic signs of flames or explosions caused by hydrogen ignition, and trigger appropriate safety measures, such as shutting down equipment or activating fire suppression systems.

In conclusion, mechanical projects in the hydrogen area have a huge impact on the development of clean and sustainable energy solutions. However, the path to widespread adoption faces numerous challenges that need to be overcome. By addressing issues related to transportation and storage, infrastructure development, energy efficiency, security and cost, we work tirelessly to unlock the full potential of hydrogen as an energy medium. As these difficulties are gradually overcome, mechanical hydrogen projects will play an increasingly vital role in building a greener and more sustainable future.

At INEGI, we support our partners and customers in overcoming the aforementioned challenges by bringing our best knowledge to meet customer needs, thus leveraging their prototypes in the hydrogen area to the market, through the development and exploration of new ideas and new challenges.

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