Hydrogen as a Fuel

Hydrogen is emerging as a key player in the shift toward cleaner energy. Once limited to industrial applications and space exploration, it is now seen as a viable alternative to fossil fuels for sectors like transportation, heavy industry, and power generation. Its biggest appeal? Zero emissions at the point of use. As governments and industries chase ambitious decarbonisation targets, hydrogen-fuelled combustion engines (H2ICEs) are being explored as a practical route toward cleaner mobility. Unlike battery electric vehicles (BEVs), H2ICEs offer rapid refuelling and longer range, making them especially attractive for heavy-duty applications where efficiency and uptime are critical.

However, hydrogen’s unique properties such as its flammability, low ignition energy, and water vapor byproducts present distinct challenges for engine performance and lubrication. Hydrogen combustion introduces entirely new conditions that impact engine wear, corrosion, and lubricant effectiveness. Water vapor can infiltrate engine components, leading to corrosion and oil emulsification, while hydrogen embrittlement poses a risk to critical parts like pistons and injectors. This article explores the critical challenges associated with hydrogen combustion engines, the development of hydrogen-compatible lubricants, and the role of advanced testing technologies in driving progress toward more efficient, durable, and sustainable hydrogen-fuelled systems.

The Rise of Hydrogen

Early Hydrogen R&D

The potential of hydrogen as a fuel source has been recognised for centuries, dating back to the 19th century. In its early days,  hydrogen was used for lighter-than-air balloons and later in rockets for its high energy output. Its journey towards being a mainstream energy carrier, however, gained momentum in the mid-20th century with the development of fuel cell technology. Hydrogen fuel cells convert hydrogen into electricity through an electrochemical reaction, producing only water and heat as byproducts. This process is highly efficient, making it particularly suitable for environments where clean, reliable power is essential. NASA notably utilised hydrogen fuel cells, such as Proton Exchange Membrane Fuel Cells (PEMFCs) and Alkaline Fuel Cells (AFCs), to power spacecraft during the Gemini, Apollo, and Space Shuttle missions, demonstrating hydrogen’s potential as a sustainable and efficient energy source [3].

The Shift Towards Sustainable Energy

The 21st century has brought with it a growing urgency to address climate change, prompting a global shift towards sustainable energy solutions. Among these, hydrogen has re-emerged as a vital contender, especially for industries that are notoriously difficult to decarbonise, such as heavy transportation and industrial heating. Unlike traditional fossil fuels, hydrogen offers the potential to drastically reduce emissions at the point of use, making it a highly attractive alternative. This potential has driven significant investment from original equipment manufacturers (OEMs), supply chain partners, and governments eager to accelerate the clean energy transition.

Supportive policy frameworks have played a pivotal role in boosting hydrogen’s prospects. In the European Union, there is potential for hydrogen-powered internal combustion engines (H2ICEs) to be classified as “Zero Emission Vehicles,” a move that could spark broader adoption [1]. In the United States, hydrogen infrastructure is being bolstered by federal tax credits for hydrogen production and the development of refuelling stations [1]. Together, these initiatives aim to create a global hydrogen economy that can underpin a cleaner energy system. However, with fossil fuels still supplying more than 84% of the world’s primary energy, scaling hydrogen adoption to a meaningful level remains a formidable but essential challenge [2]. With momentum growing and policy frameworks advancing, attention now turns to hydrogen’s role in the broader energy transition. How will this versatile energy carrier reshape the energy landscape, and which sectors stand to benefit most from its adoption?

Hydrogen’s Role in the Energy Transition

To fully realise hydrogen’s potential as a driving force in the energy transition, production and application strategies must be scaled and refined. Unlike conventional fuels, hydrogen’s role in decarbonising energy systems extends beyond transport, impacting electricity generation, industrial heating, and crucial processes in steel production, fertiliser manufacturing, and petroleum refining [2]. Each of these sectors presents unique opportunities for hydrogen to displace fossil fuels, but the pathway to integration depends on how effectively hydrogen production evolves to meet demand.

Currently, 99% of global hydrogen production relies on fossil fuels, with a large portion of hydrogen produced worldwide derived from fossil fuel-based processes. Naphtha reforming is a major contributor to carbon emissions from hydrogen production, generating around 0.9 billion tonnes of CO₂ annually [2]. Addressing this production challenge is critical to unlocking hydrogen’s wider potential. Industry efforts are underway to transition toward low-emission production methods like electrolysis powered by renewable energy. The goal is to produce 24 million tonnes of low-emission hydrogen by 2030 [2]. Achieving this target could significantly enhance hydrogen’s competitiveness against other clean energy solutions, opening up new opportunities in transport, industry, and power generation. 

However, failure to meet this goal could have far-reaching consequences. A shortfall in production capacity could limit access to affordable, low-emission hydrogen, slowing decarbonisation in sectors with limited alternative solutions. This would weaken hydrogen’s potential to disrupt fossil fuel dependency, delay climate targets, and hinder progress in industries like shipping, aviation, and heavy manufacturing. As a result, collaborative action from governments, industry stakeholders, and researchers will be essential to ensure hydrogen’s role as a cornerstone of the future energy system.

Challenges of Hydrogen Combustion Technology

Preignition Issues and Combustion Characteristics

Additionally, hydrogen’s unique combustion properties present a notable challenge for engine design. Unlike conventional fuels, hydrogen has a low ignition energy and an exceptionally wide flammability range, meaning it can ignite far more easily. This increases the likelihood of preignition and knocking, especially at high loads or under sudden throttle changes. If uncontrolled, preignition can trigger catastrophic engine failure. Hydrogen-powered internal combustion engines (H2ICEs) face this risk more acutely than conventional gasoline or diesel engines, as the combustion process can be unpredictable [1][4].

To mitigate preignition, lubrication plays a crucial role. Specially formulated engine oils aim to reduce the frequency and severity of preignition events. Tailored additive packs designed to combat stochastic pre-ignition (SPI) – the random, spontaneous ignition of fuel – are now a critical area of research. According to Afton Chemical, anti-stochastic pre-ignition additives are under development, and their work has revealed that different lubricant formulations can either exacerbate or prevent runaway preignition cycles [4]. These additives modify the oil’s volatility, control deposit formation, and reduce the chances of hot spots that could act as preignition triggers [4].

For OEMs, the stakes are high. Uncontrolled preignition can damage pistons, spark plugs, and cylinder walls, leading to premature engine failure, costly warranty claims, and downtime for fleet operators. As hydrogen combustion technology matures, lubricant companies are working to develop predictive testing models for lubricant formulations. Industry-standardised testing will be essential for ensuring the reliability of these solutions across different engine designs [1][4].

Impact on Pistons and Injectors

The internal components of hydrogen combustion engines are subjected to more intense thermal and mechanical stresses than traditional engines. The challenge is two-fold:

Hydrogen’s Combustion Byproducts: The high combustion temperatures associated with hydrogen fuel increase thermal strain on pistons, injector tips, and cylinder walls [1][4].
Fuel Delivery Differences: Unlike liquid fuels, hydrogen is a gas, and to deliver the same amount of energy, injectors must deliver a larger volume of hydrogen. This requires precision-engineered nozzles capable of managing high flow rates and avoiding turbulence [1][4].

Hydrogen embrittlement is another critical issue. This phenomenon occurs when hydrogen atoms penetrate and weaken the metal lattice of engine parts, causing microscopic cracks and fractures. Pistons, injectors, and valves are particularly vulnerable. This is a high-risk issue that can drastically reduce component lifespan, requiring OEMs to develop new alloys, surface treatments, and coatings that resist hydrogen embrittlement [1][4]. Some manufacturers are exploring the use of coated or reinforced pistons that can withstand hydrogen-induced wear [1][4].

Without suitable materials, the cost of engine repairs, unplanned downtime, and replacement of engine components would rise significantly. To address this, advanced coatings and reinforced pistons are being trialled to maintain durability under extreme pressures and temperatures [1][4].

Water Contamination in Lubricants

One of hydrogen’s defining combustion byproducts is water vapor, which introduces a new dimension of complexity for lubrication. In traditional engines, fuel combustion produces gases like carbon dioxide and water vapor, but in hydrogen engines, the proportion of water vapor is significantly higher [4]. This water vapor can penetrate the crankcase, where it accumulates in engine oil, causing:

Oil emulsification: Water mixes with engine oil, forming a milky, unstable emulsion that impacts oil flow [4].
Corrosion: The presence of water in engine components leads to rusting and pitting of metal surfaces, which can weaken critical components [4].
Freezing risks: In colder climates, water-laden lubricants can freeze, preventing proper lubrication at engine startup [4].

Tests have shown that water accumulation can reach up to 2% by volume in hydrogen combustion engines, which is far higher than in conventional engines [4]. To combat this, water-resistant additives are now being integrated into new lubricant formulations. These additives promote water separation (demulsification) or enable water to remain dispersed safely as small droplets, ensuring continuous lubrication. Emulsion stabilisers and anti-corrosion additives are essential parts of these formulations [4].

For operators, the implications are clear: if water contamination isn’t controlled, fleets face increased oil change frequencies, unplanned maintenance, and premature engine failure. Specialised lubricants with robust demulsifying properties can reduce this risk, ensuring longer drain intervals and minimising fleet downtime [4].

Leak Detection and Safety Concerns

Hydrogen’s molecular size is tiny, making it one of the most difficult gases to contain. Its small molecules can slip through minute gaps in seals, flanges, and valves. This creates a serious safety hazard, as undetected hydrogen leaks increase the risk of fire or explosion. Unlike conventional fuels, hydrogen is colourless, odourless, and difficult to detect, making early warning systems crucial [1][4].

Advanced leak detection systems are now being integrated into hydrogen combustion engines and refuelling stations. These systems employ hydrogen sensors that can detect parts-per-million (ppm) concentrations of hydrogen in the air. Modern solutions include continuous monitoring systems, which alert operators the moment a leak occurs, enabling fast intervention. Hydrogen’s tendency to dissipate quickly means it is less likely to form explosive concentrations in open spaces, but in confined areas, it poses a higher explosion risk [1][4].

Ventilation systems and flame-retardant seals are key measures used to prevent hazardous build-up. For hydrogen-powered transport, any delay in leak detection could lead to vehicle fires, which is why OEMs are designing real-time safety monitoring systems. These challenges pose significant implications for refuelling station infrastructure as well, where enhanced safety protocols must be enforced to prevent accidents [1][4].

Power Density and Fuel Storage Challenges

Hydrogen has a low energy density per unit volume, making storage a major challenge. While liquid fuels like diesel can be stored compactly, hydrogen requires high-pressure storage tanks. These tanks are bulky and heavy, taking up more space than traditional fuel tanks. For commercial vehicles and freight trucks, this means less cargo capacity and higher weight penalties [2].

Current industry standards use 700-bar pressure tanks for hydrogen storage. These tanks have thick walls made from advanced composite materials to withstand high internal pressure. However, at 700 bar, refuelling stations require specialised infrastructure to safely fill the tanks, and these systems are expensive to install and maintain. The refuelling process itself can be costly, with the price of hydrogen ranging from $1.50 to $8.00 per kilogram, depending on location and production method [2].

The knock-on effect of this challenge is seen in fleet operations. Operators face two key issues:

Reduced cargo capacity: Since high-pressure tanks occupy more space, less room is available for cargo, affecting fleet revenue [2].
High hydrogen costs: With the cost of hydrogen still significantly higher than diesel or gasoline, total operating costs increase [2].

Efforts to develop liquid hydrogen storage are underway, as liquid hydrogen is denser than gaseous hydrogen. However, liquefying hydrogen requires cryogenic temperatures, making it a costly and energy-intensive process. Without a breakthrough in storage technology, operating costs for hydrogen fleets will remain a barrier for fleet operators seeking cost parity with diesel-powered trucks [2].

PCS Instruments HPR

The Role of Precision Testing

The shift toward hydrogen as a fuel has brought unique technical challenges to light, particularly in understanding the behaviour of fuels and lubricants under extreme conditions like high pressures and reactive atmospheres. To address these complexities, precision testing technology plays an essential role.

For example, modern tribology instruments, such as the PCS Instruments HPR, enable researchers to simulate and study these specific conditions. With its ability to operate in high-pressure or vacuum environments, the HPR allows for detailed analysis of friction, wear, and material behaviour in controlled atmospheres. This capability is particularly important for testing the performance of lubricants and coatings under demanding conditions. By replicating these conditions in a laboratory setting, tools like the HPR empower researchers to identify optimal formulations and materials that enhance engine efficiency and longevity. This work not only helps overcome the challenges of hydrogen adoption but also accelerates the development of solutions needed for its practical, widespread use.

As noted by PCS Instruments’ R&D Manager, Tom Welham, “The HPR is a highly innovative instrument that allows the measurement of friction in a reciprocating contact under controlled atmospheric conditions including under vacuum and positive pressure, up to 10 bar, The removable test chamber allows blending of gases inside the chamber, under pressure, away from the instrument. This gives significant new opportunities for research, including investigating the impact on friction and wear of new sources of fuel such as hydrogen and ammonia, reactive and inert atmospheres and volatile lubricants.”

Such innovation demonstrates how cutting-edge research tools are paving the way for hydrogen-powered systems to become a viable, sustainable energy solution. By enabling controlled testing in extreme environments, these tools help inform the development of hydrogen-compatible lubricants.

Additive Development and Custom Lubricant Formulation

Specific Additives for Hydrogen Combustion Engines

For hydrogen combustion engines to reach their full potential, it is essential to develop additives that enhance the performance of lubricants under extreme conditions. These additives help to reduce preignition, prevent corrosion, and ensure lubrication under high pressure. Custom additives can also address the challenges of water contamination and oxidative stress from high combustion temperatures. Additionally, detergents and dispersants, though less critical due to hydrogen’s cleaner combustion, need to be carefully optimised for hydrogen engines [1].

Custom Lubricant Formulations for H2ICE

The development of tailor-made lubricants for hydrogen combustion engines is a critical step in optimising performance. These formulations must include preignition inhibitors, robust antioxidants, and water-resistant additives to handle unique challenges such as increased water accumulation in engine oils and higher combustion temperatures. Preignition inhibitors are essential for mitigating stochastic pre-ignition (SPI), a random ignition event that can cause severe engine damage if left unchecked. Water-resistant additives play a vital role in forming stable emulsions, ensuring that water infiltration into the lubrication system does not compromise lubrication effectiveness or engine protection [4].

Recent advancements in lubricant formulations have focused on additive packages that tackle multiple issues simultaneously. These packages aim to reduce preignition risks, prevent water-induced corrosion, and maintain oil pumpability at low temperatures. According to Lubes & Greases, these multi-functional additives balance protection against preignition and water contamination while ensuring lubrication effectiveness over extended drain intervals [4]. This is particularly significant for hydrogen engines, where water vapor, a primary byproduct of hydrogen combustion, poses a contamination risk to lubricants [4].

Prototypes of these advanced lubricants are being developed to meet stringent performance requirements, but comprehensive field testing and collaborative research between academia, industry, and government remain crucial for validation. Collaborative efforts are also essential for creating industry standards that guide OEMs and lubricant manufacturers in developing hydrogen-compatible engine oils that offer long-term reliability and cost-effectiveness [1][4].

Trends in Hydrogen Fuel Adoption

As hydrogen technology matures, it is expected that the use of hydrogen combustion engines will expand across multiple industries. H2ICEs are particularly promising for heavy-duty applications, where hydrogen offers faster refuelling times and longer range compared to battery electric vehicles (BEVs). Furthermore, lifecycle assessments indicate that hydrogen combustion systems could be less carbon-intensive than BEVs in regions where electricity generation remains fossil-fuel dependent [1].

Real-world projects are accelerating the transition to hydrogen-powered transportation. For instance, the Southwest Research Institute (SwRI), as part of a Joint Industry Partnership, is commissioning an H2ICE on a commercial heavy-duty truck to evaluate its road performance. This initiative underscores hydrogen’s potential to meet the demands of heavy-duty sectors, particularly those requiring high power and long-range capabilities. Such demonstrations are essential for validating hydrogen’s viability and refining the necessary technologies [1].

The hydrogen-powered transport sector is witnessing rapid growth, with extensive research aimed at reducing costs and emissions. Global hydrogen demand for transportation is expected to rise to 8 million tonnes by 2030, fuelled by advancements in hydrogen refuelling infrastructure and technology [2].

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The Role of Research and Innovation in Overcoming Challenges

Ongoing research and technological advancements are proving essential in addressing the challenges of hydrogen combustion. Precision instruments like the HPR play a key role in generating insights that support the development of more efficient, durable, and hydrogen-compatible lubricants. By enabling controlled testing under high-pressure and reactive environments, tools like these provide vital data on friction, wear, and the chemical interactions within hydrogen-powered systems. This knowledge is instrumental in refining lubricant formulations that can withstand the unique stresses posed by hydrogen combustion [1].

Beyond technical advances, industry-wide collaboration is driving progress. Support from government subsidies, OEM investments, and industry-academic partnerships has created a fertile environment for innovation. For example, government-backed initiatives are encouraging the development of low-emission hydrogen production methods and advancing research into hydrogen-compatible engine components. These efforts aim to create the conditions necessary for a wider hydrogen economy, one that can support H2ICEs as well as other hydrogen-powered systems [1][2].

Collaborative Efforts for Sustainable Energy Solutions

Achieving large-scale adoption of hydrogen requires the combined effort of industry leaders, researchers, and policymakers. Collaborative partnerships are tackling key obstacles such as supply chain bottlenecks, lubricant formulation innovations, and the durability of critical engine components. These efforts ensure that hydrogen combustion engines remain a viable and cost-effective option for decarbonisation.

A crucial focus of these partnerships is securing policy support. Industry groups are working to establish clear regulatory standards for H2ICEs, including proposals for zero-emission vehicle classification. If successful, these policy changes could open the door for wider adoption of hydrogen-powered technology in commercial sectors [1][2]. Collaborative efforts like these are shaping the future of hydrogen’s role in the energy transition, turning what was once an experimental fuel into a genuine contender for clean energy systems.

Conclusion

Hydrogen stands at the forefront of the shift to cleaner energy, offering a crucial alternative to fossil fuels for hard-to-decarbonise sectors like heavy transport and power generation. From its early role in aerospace fuel cells to its modern-day potential as a versatile energy carrier, hydrogen’s place in the global energy mix is rapidly evolving. Hydrogen internal combustion engines (H2ICEs) are emerging as a key bridge technology, especially in applications where battery electrification alone may fall short.

However, realising hydrogen’s full potential is no simple feat. Technical challenges like preignition, water-induced corrosion, and hydrogen embrittlement continue to test engine materials and lubrication technologies. Overcoming these hurdles demands collaboration between OEMs, lubricant manufacturers, and regulatory bodies. Innovations in precision testing, such as PCS Instruments’ HPR, and the development of hydrogen-compatible lubricants are advancing solutions that ensure engine reliability and efficiency.

While the road ahead is not without challenges, it is one filled with opportunity. Industry partnerships, policy support, and advances in hydrogen-compatible lubricants and infrastructure are bringing H2ICEs closer to commercial reality. If the sector can meet the technical and production challenges head-on, hydrogen could become one of the most significant contributors to a net-zero future.

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References

[1] Society of Tribologists and Lubrication Engineers. (2024, October). Hydrogen-fuelled internal combustion engine technology moves toward commercialization. Tribology & Lubrication Technology. Retrieved from https://www.stle.org/files/TLTArchives/2024/10_October/Feature.aspx

[2] Halder, P., Babaie, M., Salek, F., Haque, N., Savage, R., Stevanovic, S., Bodisco, T. A., & Zare, A. (2024). Advancements in hydrogen production, storage, distribution, and refuelling for a sustainable transport sector: Hydrogen fuel cell vehicles. International Journal of Hydrogen Energy, 52(1), 973–1004. https://doi.org/10.1016/j.ijhydene.2023.07.204

[3] Burke, K. A. (2003). Fuel cells for space science applications (NASA/TM-2003-212730, AIAA–2003–5938). National Aeronautics and Space Administration, Glenn Research Center. Available at https://ntrs.nasa.gov/citations/20040010319

[4] Lubes & Greases. (2024, April 30). The same but different: The unique lubricant challenges of hydrogen engines. Retrieved from https://www.lubesngreases.com/magazine/30_5/the-same-but-different-the-unique-lubricant-challenges-of-hydrogen-engines/