L. JOHNSON and A. SMITH, Luxfer Gas Cylinders, Nottingham, United Kingdom

The availability of alternative fuels such as hydrogen (H₂) is a critical factor in the decarbonization of transportation, particularly because the UK government is targeting H₂ to deliver 20%–35% of total final energy consumed across the country by 2050.

However, several significant barriers must be overcome if H₂ is to realize its potential as a sustainable power source for not just the mobility sector, but for industry in general.

Designing H₂ mobility systems: One size does not fit all. Significant progress has been made to adopt cleaner fuel to power buses, trains, trucks, tractors and a range of off-road vehicles and plant machinery. However, what has become apparent is that H₂ is presently better suited to some applications than others.

For example, H₂ as fuel for the maritime and aviation sectors is a more complex proposition than for on-road (e.g., the regulatory landscapes are completely different).

Furthermore, in terms of maritime, saltwater corrosion is a key challenge to address. As such, it is all about product quality—cylinders, systems and components must be able to withstand the harsh environment of exposure to humidity and salt.

Rail, too, presents operational, commercial and design concerns.

Despite substantial innovation and development to enable the safe and efficient storage and transportation of H₂ via road, a myriad of engineering complexities must be considered, particularly in terms of system design.

For one, gas cylinders are inherently heavy, and the weight of the cylinder and the system itself is fundamental. Space is another concern. Systems must fit within designated spaces, and the best way to mount solutions must be assessed.

When it comes to how a system is designed, considerations such as the placement of other vehicle components are also important. For example, an element that could inadvertently heat up the cylinder, and the gas within it, must be considered.

Beyond these design challenges, component availability—especially parts that meet the required standards and with time-served reliability—can be a factor. This is exacerbated by supply chain delays, as well as by demand for materials from faster-moving markets. 

The current trend in the transport sector is to take a bespoke approach to developing complex H₂ systems across many different vehicle platforms, with each build designed to a specific customer brief. There is no one-size-fits-all solution. The ideal would be one standardized system per vehicle application that fits, works and is then tailored to each customer’s needs.

Moving towards this type of standardization will drive down lead times and costs and ensure the ongoing availability of reliable components, all of which should help impel wider adoption.

H₂ storage: Cylinder choice and benefits. Another crucial consideration for the sector is how H₂ is stored as part of the system to power buses, trucks, trains and other modes of transport. Here, cylinder choice plays a significant role: Type 3 and Type 4 cylinders are the most common types used in mobility applications. Each has different core benefits, with product selection based upon the application and the brief.

Type 3 aluminium-lined cylinders are robust, fill faster and are non-permeable—they have been a preferred choice of pioneers and original equipment manufacturers (OEMs) for many years.

Plastic-lined Type 4 cylinders deliver high storage volumes while remaining lightweight, offering a cost-effective H₂ storage solution ideal for long-range rail, boats and other vehicles.

While Type 3 cylinders are heavier, Type 4 cylinders often require H₂ to be chilled before filling as the heat produced in a fast-fill system could cause internal damage to the liner. Each has its merits based on what is most critical to the user’s operation. In its work with major OEMs on world-leading projects, the authors’ company uses its decades of experience to help customers make suitable decisions for their applications.

Strict safety and standards for H₂ systems. High-pressure H₂ cylinders are designed to meet strict performance requirements and are tested against stringent regulations and standards. Generally, these cylinders undergo a strict testing regime (e.g., extreme temperature testing, drop and impact testing, gunfire testing, fatigue cycle, burst testing).

While regulations are in place—the authors’ company was one of the first manufacturers to achieve approval for Regulation No. R134, a global safety regulation that highlights that cylinders are safe for use in H₂-powered vehicles across a wide range of applications—it is important to note that not all H₂ cylinders in the market meet the required standards.

Despite cylinders meeting regulatory requirements and undergoing rigorous testing, there can be negative rhetoric around the safety of H₂, with the general perception being that it presents a substantial risk.  

This is compounded by the absence of standardized regulations for many mobility applications. Establishing clear guidelines and regulations across the entire supply chain and addressing concerns related to safety is vital to nurture confidence in H₂ systems among companies that may be looking to invest in greener, more sustainable solutions as part of their carbon reduction strategies (FIG. 1).

Connecting the dots: A pathway to an efficient H₂ network. Another challenge preventing the wide-scale adoption of H₂ for transportation is that there is still potential to make the fuel more accessible.

The widespread adoption of the gas—not just in the mobility sector, but across the wider industry—is hinged on the development of fueling infrastructure. While some progress has been made, continued efforts are required to create a comprehensive and accessible H₂ infrastructure.

One way to address the H₂ infrastructure deficit is by developing bulk gas transport systems. These ‘virtual gas pipelines’ can help connect the dots between H₂ production and consumption by bridging the gap between the point of production and the point of use.

They allow operators to decarbonize transport while providing the means to move the gas in a scalable way. Crucially, they offer a stepping stone until dedicated pipeline infrastructure is established and can provide either temporary or permanent solutions to delivery or capacity difficulties. The authors’ company is among the companies pioneering in this space.

Takeaway. The future of H₂ transportation will likely involve a combination of physical and virtual pipelines, with each solution utilized to meet different needs across the supply chain. Once physical pipelines are established—according to literature,¹ approximately 2,000 km of the existing gas network is expected to be repurposed into a 100% H₂ ‘backbone network’ by the early 2030s—it is unlikely to result in the disuse of virtual gas pipelines. Instead, the latter will likely be redeployed to best service the first and final miles of distribution. 

H₂ holds immense promise for a more sustainable and environmentally friendly transport sector. The authors’ company is at the forefront of making clean gas more accessible through constant innovation that will make a difference for future generations. H₂T

LITERATURE CITED

¹ National Gas Transmission, ICE, “How National Grid Gas is unlocking the potential to deliver a net zero future,” online: https://www.ice.org.uk/news-insight/news-and-blogs/ice-blogs/the-infrastructure-blog/national-grid-gas-industry-briefing 

About the authors

Louis Johnson joined Luxfer Gas Cylinders in 2014 as a Design Engineer. Initially offering support on aluminium cylinder design and manufacturing process improvements, he transferred to the Alternative Fuel team in 2017, forming part of the group that established the manufacturing capability for alternative fuel systems at the company’s Nottingham site. Since then, Johnson has worked on several world’s-first H₂ projects with both OEMs and H₂ pioneers. During his tenure, he has also completed several professional skills development courses, including project management, finite element analysis and Advanced Autodesk Inventor.

Adam Smith joined Luxfer Gas Cylinders in 2018 as a junior CAD Apprentice and has swiftly progressed through the ranks. After completing his NVQ and full extended diploma, he was promoted to CAD Technician, followed by a subsequent promotion to Alternative Fuel System Designer upon completion of courses in finite element analysis and project management. In addition to his role at Luxfer Gas Cylinders, Smith is currently studying towards a higher national diploma in mechanical engineering at Nottingham Trent University.