In a revolutionary approach, researchers at King Abdullah University of Science and Technology (KAUST) have explored the potential of Liquid Organic Hydrogen Carriers (LOHCs) as a practical, safe, and scalable alternative for hydrogen storage. LOHCs are carbon-based molecules capable of chemically bonding with hydrogen, transforming into stable hydrogen-rich liquids that can be handled far more easily than hydrogen gas. This technology promises to leverage existing petrochemical infrastructure, sidestepping the need for expensive and complex new facilities.

The KAUST team pushed the boundaries of LOHC application by investigating whether these compounds could be stored underground in depleted oil fields—a novel idea that marries energy storage with enhanced oil recovery. Their simulations focused on sandstone reservoirs typical of Saudi Arabia’s oil-producing regions, exploring the interplay between LOHC characteristics and subsurface conditions at depths around 2,200 meters. The findings suggest that certain LOHCs can not only store large quantities of hydrogen securely but also coax residual oil from these aging reservoirs, providing a dual economic and environmental benefit.

Central to this study was the evaluation of two distinct LOHC systems. The first employed toluene, a well-known petrochemical, which chemically bonds with hydrogen to form methylcyclohexane. Both molecules boast stability and availability, with toluene storing roughly 6.2 percent of its weight in hydrogen. Methylcyclohexane’s low viscosity allows it to flow smoothly underground, making it especially suitable for injection and recovery in porous rock formations.

Simulations revealed a promising operational cycle where methylcyclohexane was injected into the depleted reservoir over a five-month period, followed by a two-month rest phase, and then extracted over another five months. Repeating this yearlong injection-extraction cycle 15 times demonstrated that roughly 75 percent of the methylcyclohexane could be recovered each cycle. Remarkably, the process also enhanced oil recovery by more than 50 percent over the simulation period. This synergy implies that the value generated by extracting additional oil could offset the costs of hydrogen storage, with total net benefits estimated at around $70 million.

In sharp contrast, the second LOHC system examined, despite having a higher hydrogen capacity per molecule, stumbled due to its elevated viscosity. The thicker liquid faced greater resistance during underground injection and extraction, reducing efficiency and recovery. This highlights the critical balance between hydrogen storage density and flow properties that must be optimized for successful field deployment.

While the enhanced oil recovery aspect might seem contradictory to climate goals, leading to some downstream carbon dioxide emissions, experts argue these are minimal compared to the climate advantages achieved through widespread hydrogen utilization. Using LOHCs for hydrogen storage in depleted fields provides a viable stepping stone to decarbonization by leveraging existing fossil infrastructure during a transitional energy phase.

Moreover, the chemical nature of LOHCs secures hydrogen effectively, enabling storage under mild conditions without the need for high-pressure or cryogenic technologies. This feature drastically reduces technical risks and lowers barriers for integration into current fuel distribution networks, including pipelines, tankers, and large storage facilities, facilitating faster adoption.

The KAUST researchers now aim to expand their models to more complex multi-well reservoir systems, reflecting more realistic oil field infrastructures where multiple injection and production wells operate simultaneously. Such scenarios could reveal additional dynamics in the interaction between LOHCs, hydrogen, and subsurface geology, potentially optimizing storage and recovery processes on a commercial scale.

This innovative approach offers a hopeful avenue for reconciling the urgent need for hydrogen-based clean energy with practical and economic feasibility. By transforming depleted oil fields into dual-purpose hydrogen storage and oil recovery sites, LOHC technology could accelerate the transition to a low-carbon energy system while leveraging and repurposing existing infrastructure.

Importantly, this research underscores the value of interdisciplinary strategies—blending chemistry, petroleum engineering, and environmental science—to tackle complex energy challenges. As the world presses forward in its quest to reduce carbon emissions, innovations like LOHC-based underground hydrogen storage highlight how existing resources and emerging technologies can be aligned to create sustainable energy solutions.

In conclusion, the deployment of LOHCs as subterranean hydrogen carriers not only addresses technical and economic obstacles but also introduces a pragmatic blueprint for integrating renewable hydrogen within the fossil fuel landscape. If successfully scaled, this approach could play a pivotal role in shaping the global energy transition, making clean hydrogen more accessible and commercially viable while contributing to incremental oil recovery that financially supports the venture.

Subject of Research: Liquid Organic Hydrogen Carriers for underground hydrogen storage and enhanced oil recovery

Article Title: Techno-economic assessment of field-scale storage for liquid organic hydrogen carriers: dual benefits of energy storage & incremental oil recovery

News Publication Date: 15-Apr-2026

Web References: https://doi.org/10.1016/j.fuel.2025.137906

References: Tariq, Z., AlSubhia, M., Alia, M., Kumara, N., Alissab, F., Ghamdi, A., & Hoteit, H. Fuel 410, 137906 (2026).

Keywords

Liquid Organic Hydrogen Carriers, LOHC, Hydrogen Storage, Enhanced Oil Recovery, Residual Oil, Sustainable Energy, Carbon Emissions, Subsurface Storage, Methylcyclohexane, Toluene, Fossil Fuel Transition, Energy Infrastructure

Transporting hydrogen safely over long distances presents a formidable challenge due to hydrogen’s low energy density and high flammability. Ammonia, composed of nitrogen and hydrogen atoms, offers a compelling alternative because it can store twice the energy density of compressed hydrogen and be transported using existing infrastructure more efficiently. Scientists envision using ammonia as a molecular shuttle: hydrogen can be chemically embedded within ammonia and then released on demand wherever needed. This paradigm shift could transform the energy landscape by decentralizing hydrogen production, minimizing the scale and complexity of industrial facilities, and reducing the associated costs and risks of hydrogen transportation.

Historically, ammonia synthesis has relied heavily on the Haber-Bosch process, which requires extreme temperatures exceeding 400°C and pressures over 150 atmospheres. This method demands massive, centralized plants equipped with expensive machinery and substantial energy inputs. The energy-intensive nature of Haber-Bosch poses scalability and sustainability challenges, particularly as the world seeks greener industrial methods. The new plasma-catalyzed approach devised by a multidisciplinary team from the Princeton Plasma Physics Laboratory (PPPL), Rutgers University, Oak Ridge National Laboratory, Rowan University, and Princeton University promises a low-energy, highly efficient alternative. This innovation utilizes low-temperature plasma, electric energy, water, and nitrogen to facilitate ammonia formation at or near room temperature.

Plasma, often referred to as the fourth state of matter, consists of a partially ionized gas in which electrons attain very high energies while the bulk gas remains relatively cold. This unique environment enables chemical reactions that are inaccessible under conventional conditions. By harnessing plasma’s energetic electrons, researchers induce fundamental changes in catalyst surfaces, triggering atomic rearrangements that promote ammonia synthesis. The process creates reactive sites on the catalyst where nitrogen molecules from the air can be activated and combined with hydrogen atoms derived from water. This method not only reduces the synthesis temperature and pressure but also dramatically accelerates the reaction rate.

A central breakthrough enabling this technology revolves around the design and fabrication of a specialized catalyst exhibiting a heterogeneous interfacial complexion (HIC). The catalysts, primarily composed of tungsten oxide and tungsten oxynitride, are not new as materials; however, their configuration and preparation method represent a major advancement. The plasma-enabled synthesis technique allows precise control over the catalyst’s surface structure at the atomic level, facilitating the creation of nitrogen vacancies—tiny voids perfectly sized to trap nitrogen molecules. Hydrogen atoms generated on the catalyst readily occupy adjacent sites, prompting an efficient conversion of nitrogen into ammonia molecules.

The synergy between nitrogen vacancies and active hydrogen atoms is the cornerstone of this catalyst’s enhanced performance. The vacancies act as attractors, binding nitrogen molecules and holding them in place, while the hydrogen atoms rapidly interact with these activated nitrogen centers. This cooperative effect minimizes the occurrence of undesirable side reactions, such as hydrogen gas formation, which traditionally compete with ammonia production. Consequently, the method not only increases the yield of ammonia but also improves selectivity and energy efficiency, marking a significant leap beyond existing catalytic technologies.

Time efficiency is another critical asset of the plasma-based approach. Traditional catalyst preparation can take upwards of two days under specialized conditions, hindering rapid experimentation and scale-up. In contrast, the plasma-enabled fabrication process drastically reduces this timeframe to mere minutes. This rapid synthesis capability accelerates research cycles and opens avenues for mass production, making it highly attractive for industrial adaptation. Early experimental results, as outlined by doctoral candidate and lead researcher Zhiyuan Zhang, demonstrate that ammonia output surpasses that of catalysts produced by conventional methods, indicating the method’s practical value.

Fundamental to understanding and optimizing these developments are high-fidelity simulations performed at the atomic scale. Modeling the complex quantum chemistry involved in plasma catalysis requires detailed observation of atomic interactions during ammonia synthesis. PPPL’s research physicist Mark Martirez is spearheading simulation efforts that elucidate the precise mechanisms at play, clarifying how plasma-excited electrons modify catalyst surfaces and how hydrogen and nitrogen atoms migrate and interact. Such computational insight is instrumental in guiding catalyst design and process parameters to maximize efficiency and scalability.

The plasma approach also offers potential sustainability advantages. Because it relies on electricity rather than fossil-fuel-derived heat, it integrates well with renewable energy sources such as solar and wind. Coupling plasma-driven ammonia synthesis with renewable electricity could substantially lower the carbon footprint of fertilizer and hydrogen production, supporting broader climate goals. Moreover, the decentralized nature of the technology could democratize ammonia and hydrogen supply chains, enabling localized production in remote or underserved regions.

The collaborative effort behind this research exemplifies the convergence of plasma physics, materials science, chemistry, and engineering. Institutions such as the U.S. Department of Energy’s PPPL and Oak Ridge National Laboratory have contributed unique expertise, alongside academic partners at Rutgers and Princeton Universities. This multidisciplinary synergy accelerates innovation, blending theoretical modeling, experimental plasma generation, catalyst synthesis, and advanced characterization techniques.

Looking ahead, challenges remain in scaling up the plasma catalysis process for commercial applications. Researchers are focused on refining catalyst durability, optimizing plasma reactor designs, and integrating ammonia decomposition technologies for onsite hydrogen retrieval. Continued research will expand understanding of plasma-material interactions and explore ways to tailor catalysts for broader chemical pathways. The ultimate goal is to establish comprehensive energy systems where ammonia serves as a versatile, safe energy carrier bridging production, storage, transportation, and utilization.

As the world races to find sustainable solutions for energy and chemical manufacturing, plasma-enabled ammonia synthesis represents a compelling milestone. By radically changing how ammonia is produced and harnessed, this innovation has the potential to reshape global energy infrastructure, making hydrogen storage and distribution less hazardous, more efficient, and economically viable. This exciting development heralds a future where plasma catalysis underpins not only fertilizer production but also the clean energy transition, ultimately contributing to a more sustainable and resilient energy ecosystem.

Subject of Research: Plasma catalysis for ammonia synthesis and hydrogen storage
Article Title: (Not provided)
News Publication Date: 22-Jun-2025
Web References:
– U.S. Department of Energy: https://www.energy.gov/
– Princeton Plasma Physics Laboratory: https://www.pppl.gov/
– DOI: http://dx.doi.org/10.1021/acsenergylett.5c01034

References:
ACS Energy Letters, DOI: 10.1021/acsenergylett.5c01034

Keywords:
Energy, Chemical compounds, Chemical processes, Electricity, Ammonia, Hydrogen