Liquid Organic Hydrogen
Carriers (LOHC): A Game Changer
Setting
the context – Hydrogen storage challenge
Hydrogen
is a promising clean energy source but its biggest challenge lies in
transportation and storage
methods due to its low density at ambient conditions.1 Standard
methods compress hydrogen at high pressure (350 - 700 bar) and liquefy it at
temperatures -253 °C, but they are costly and suffer from
safety issues. This reveals an obvious need for a denser, safer, and cheaper
method of moving hydrogen – that’s where LOHCs come in.2
What
is LOHC? LOHC is a technology that allows hydrogen to be chemically bonded to a
liquid carrier, making it safer and more efficient to handle. Think of LOHC
technology like a rechargeable liquid battery for hydrogen. Hydrogen gas is
chemically absorbed into this liquid, almost like dissolving sugar in water,
but it's held much more securely. When you need the hydrogen for fuel, you can
heat the liquid to release the pure hydrogen gas.3 The liquid can
then be recharged with hydrogen again.
The
biggest advantage is that this hydrogen-filled liquid is safe and easy to
handle at normal temperatures and pressures, just like gasoline or diesel. This
means LOHCs can leverage the existing global infrastructure and reduces the
investment needed for building a hydrogen economy.
How
LOHCs Work: A Reversible Cycle
As
mentioned earlier, the LOHC process operates two-step chemical cycle powered by
catalysts.
1.
Hydrogenation (Charging): Hydrogen is reacted with an
unsaturated “hydrogen-lean” carrier (LOHC⁻), typically an aromatic
compound, at elevated pressure (30 - 50 bar) and temperature (150 - 200 °C). This exothermic reaction
occurs since a catalyst guides that reaction and saturates the molecule. Then
it creates a stable, “hydrogen-rich” carrier (LOHC⁺) that safely stores all the
hydrogen.4
2.
Dehydrogenation
(Discharging):
At the point of use, the hydrogen-rich LOHC⁺ is heated to higher
temperatures (250 - 350 °C) in the presence of a
different catalyst. This endothermic reaction breaks the chemical bonds and
releases high-purity hydrogen gas. The original "hydrogen-lean" LOHC⁻ is regenerated and can be
transported back to be recharged, making the carrier itself a reusable carrier.4
Hydrogenation
releases heat so this heat can be used within other industrial processes,
whereas dehydrogenation step can be powered by sources like data centers or
steel mills by low-cost waste heat.
Comparing
Hydrogen Storage Vectors
No
single hydrogen
storage technology is perfect; the best choice depends on the application.
LOHCs uniquely balance safety, density, with infrastructure compatibility,
making them a compelling option, especially for large-scale and long-distance
transport.
Table 1.
Comparative analysis of hydrogen storage technologies5
|
Feature |
Compressed
Gas H2 (700 bar) |
Liquid
H2 (L H2) |
Ammonia
(Liquid) |
Metal
Hydrides (Solid) |
LOHC
(Dibenzyltoluene) |
|
Volumetric Density, Kg.H2/m3 |
~40 |
~71 |
~121 |
~100-150 |
~57 |
|
Gravimetric Density, wt.% |
~5-6
(System) |
~10-12
(System) |
~17.6
(Molecule) |
~2-4
(System) |
~6.2
(Molecule) |
|
Storage Conditions |
700
bar, Ambient Temp. |
1
bar, -253 °C |
8-10
bar, Ambient Temp. or 1 bar, -33 °C |
Ambient
P & T |
Ambient
P & T |
|
Key Safety Concerns |
High-pressure
explosion risk |
Cryogenic
burns, flammability, boil-off |
High
toxicity, corrosive |
Pyrophoric
(some materials) |
Low
toxicity (diesel-like), flammability |
|
Infrastructure |
Requires
new high-pressure infrastructure |
Requires
new cryogenic infrastructure |
Established,
but requires specialized handling |
No
existing infrastructure |
Compatible
with existing liquid fuel infrastructure |
|
Technology Readiness Level (TRL) |
High
(8-9) |
High
(7-8) |
High
(8-9, as chemical) |
Low-Medium
(4-6) |
Medium-High
(6-8) |
The
LOHC Material Landscape
When
choosing carrier molecule, one needs to always think about their performance,
mature, and cost. An ideal LOHC would be defined through high hydrogen capacity
(>6 wt.%), a wide liquid temperature range, and low dehydrogenation energy
requirements.
● Cycloalkanes
are the main
commercial front-runners in the LOHC landscape. Industrial giants such as
Honeywell UOP and Axens acquire mature and low-cost Toluene/Methylcyclohexane
(MCH) system.12
● Dibenzyltoluene
(DBT) from
Hydrogenious LOHC Technologies is favored for its safety profile as well as
liquid range. Both systems offer good hydrogen capacity (~6.2 wt.%) but still
suffer from high dehydrogenation enthalpies requiring high temperatures (~300 °C) for release of hydrogen.13
● N-Heterocycles
(e.g., N-ethylcarbazole):
These molecules are a major focus of research. Since nitrogen reduces
dehydrogenation enthalpy, hydrogen release occurs at efficient lower
temperatures. However, these materials are less developed materials with high
melting points often making them solid and are still under investigation
regarding large-scale production.
Table 2.
Properties of main LOHC systems16
|
LOHC
System |
Gravimetric
H2 Capacity (wt%) |
Dehydrogenation
Enthalpy (kJ/mol H2) |
Typical
Dehydrogenation Temp (°C) |
Key
Advantages |
Key
Disadvantages |
|
Toluene / MCH |
6.2 |
~65 |
300-350 |
Low
cost, high availability, mature technology |
High
dehydrogenation temperature, catalyst coking, toluene toxicity |
|
Dibenzyltoluene (DBT) |
6.2 |
~65.4 |
270-320 |
Wide
liquid range, high boiling point, good safety profile |
High
dehydrogenation temperature, higher cost than toluene |
|
N-Ethylcarbazole (NEC) |
5.8 |
~50.5 |
180-250 |
Lower
dehydrogenation temperature and enthalpy |
High
melting point (solid at RT), higher cost, less mature |
Overcoming
Key Challenges
LOHC
technology's viability hinges on two factors: catalysts and system integration.
Dehydrogenation is indeed the main catalytic conundrum, which is the key
challenge. It relies on highly effective but expensive metals like platinum
(Pt) and palladium (Pd). This is also a major challenge for deployment. Current
research mainly seeks to develop more abundant, cheaper non-noble metal
catalysts (like nickel) or more efficient bimetallic catalysts to reduce costly
metals.14
Another
challenge lies in system Integration, where the most critical economic problem
is heat integration. The system's efficiency can improve dramatically using
waste heat from nearby industrial processes to power the endothermic
dehydrogenation reaction, and it becomes more cost-effective.15 This
makes LOHC technology appropriate for industrial clusters, ports, and heavy
transport applications where waste heat exists.
Available
Technologies
LOHC
technology is moving from the lab to the real world, driven by a dynamic
commercial ecosystem.
● Key
Players:
Germany's Hydrogenious LOHC Technologies
is a pioneer focusing on DBT-based systems.7
● Industrial giants: Honeywell UOP and the Franco-Japanese
alliance of Axens and Chiyoda are leveraging their deep
petrochemical expertise with the Toluene/MCH system.8
● Flagship
Projects:
The technology has been proven within the world's first international hydrogen
supply chain, since it transports hydrogen from Brunei to Japan via LOHC. Other
projects are focused on decarbonizing maritime shipping and repurposing
existing oil pipelines to carry LOHCs, and they show the technology's
infrastructure advantage.9
Strengths
and Weaknesses
● Strengths: It includes high volumetric
density, compatibility with existing liquid fuel infrastructure, and unrivaled
safety. Another strength lies within long-term lossless storage potential.5
● Weaknesses: The energy requirement for
dehydrogenation, the high cost and durability concerns of platinum catalysts,
and a lower gravimetric density compared to liquid hydrogen.10
The
Path Forward
In a
multi-vector hydrogen economy, different carriers will likely be involved in
the future of energy, suited for different tasks.11 LOHC technology
is uniquely positioned to become the logistical backbone of a global hydrogen
trade, while pipelines may dominate short-distance transport and liquid
hydrogen may serve niche applications like aviation. It is able to safely and
economically transport massive quantities of hydrogen over longer distances
with existing infrastructure. This in effect enables green molecules for their
ultimate game-changing potential while continued innovation with
low-temperature catalysts along with smart heat integration within the clean
energy transition.
References
1.
Hydrogen Storage |
Department of Energy, accessed July 30, 2025, https://www.energy.gov/eere/fuelcells/hydrogen-storage
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Liquid Organic
Hydrogen Carriers (LOHCs): Toward a Hydrogen-free Hydrogen Economy | Accounts
of Chemical Research - ACS Publications, accessed July 30, 2025, https://pubs.acs.org/doi/10.1021/acs.accounts.6b00474
3.
LOHC technology:
accelerating the deployment of hydrogen storage and fuel cell electric vehicles
| Umicore, accessed July 30, 2025, https://www.umicore.com/en/media/newsroom/lohc-technology/
4.
LOHC-Technology
Overview - H2-Enterprises, accessed July 30, 2025, https://h2-enterprises.com/lohc-technology-overview/
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Large-scale
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2025, https://www.hydrogen-expo.com/industry-news/three-companies-develop-lohc-sofc-power-system-maritime
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Critical
challenges towards the commercial rollouts of a LOHC-based H2 economy | Request
PDF - ResearchGate, accessed July 30, 2025, https://www.researchgate.net/publication/370886974_Critical_challenges_towards_the_commercial_rollouts_of_a_LOHC-based_H2_economy
11.
Potential
Liquid-Organic Hydrogen Carrier (LOHC) Systems: A Review on Recent Progress,
accessed July 30, 2025, https://www.researchgate.net/publication/347052807_Potential_Liquid-Organic_Hydrogen_Carrier_LOHC_Systems_A_Review_on_Recent_Progress
12.
Liquid organic
hydrogen carrier - Wikipedia, accessed July 30, 2025, https://en.wikipedia.org/wiki/Liquid_organic_hydrogen_carrier
13.
What is LOHC
(Liquid Organic Hydrogen Carrier)? - Decentralised Energy Canada, accessed July
30, 2025, https://www.deassociation.ca/newsfeed/what-is-lohc-liquid-organic-hydrogen-carrier
14.
Novel Catalysts
for Dibenzyltoluene as a Potential Liquid Organic Hydrogen Carrier Use—A
Mini-review | Request PDF - ResearchGate, accessed July 30, 2025, https://www.researchgate.net/publication/351409214_Novel_Catalysts_for_Dibenzyltoluene_as_a_Potential_Liquid_Organic_Hydrogen_Carrier_Use-A_Mini-review
15.
LOHC-Technology
Overview - H2-Enterprises, accessed July 30, 2025, https://h2-enterprises.com/lohc-technology-overview/
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