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Friday, May 30, 2025

Transfer of Liquid Hydrogen

Effect of LH2 Injection Method on Receiving Tank Pressure and Temperatures [1]

Distribution costs are driven by the delivery modes chosen. For scenarios where LH2 is produced onsite and transferred to a nearby or onsite storage or fueling facility, vacuum-jacketed transfer piping, valves, fittings, pumps, and other necessary equipment to support draining and filling of storage tanks are required.

For offsite ground transport, a fleet of trucks and LH2 trailers are needed to meet delivery frequency. Interface systems for loading or offloading are also required at all distribution sources and delivery locations. Rail service may be an alternative ground transport option for some locations subject to similar requirements for mobile storage, delivery schedules, and interface systems. Shipping by barge or tanker ship is an option where port infrastructure is in place to support loading and offloading.

The currently dominant LH2 distribution paradigm involves liquefaction plants owned and operated by a few incumbent companies (e.g., Air Liquide, Linde, and Air Products). LH2 produced at these facilities is primarily distributed to large, existing customers in over-the-road trailers. Delivery by barge and train is less common. In some cases, the customers’ LH2 receiving and storage system is leased from the provider.

This distribution approach is growing in popularity as more customers ramp up their LH2 usage. Additional distribution scenarios and providers are also coming online to meet various LH2 customer requirements for new applications, locations, quantities, and delivery frequencies. Smaller and more modular liquefaction systems have become commercially available to provide capabilities as needed. Small scale liquefaction is particularly in demand for mobility applications that are under development. As these applications scale up in the market, reliable but flexible LH2 distribution will be critical to ensure commercialization success.

For very large-scale, intercountry distribution, new import–export trade deals are being implemented in some global markets. Regions with an abundance of renewable energy and feedstock resources can produce, liquefy, and export LH2 to regions with high demand that have more constrained or costly production resources.

Conversely, island nations and other remote or isolated regions can combine the entire production, liquefaction, delivery, and end use in one location. This unique characteristic of hydrogen relative to fossil fuels eliminates the need for long-distance distribution altogether. Other hybrid approaches are also being developed, such as distribution of gaseous hydrogen via pipelines to be liquefied onsite at the point-of-use. 

Thermal management of LH2 and mitigation of boil-off throughout the delivery pathways is critical to minimizing hydrogen loss and associated costs. Identifying the appropriate options to mitigate boil-off losses requires systems engineering to identify the best trades for a particular use case.

References

[1] Image source: Liquid Hydrogen Systems Course, 2025.
[2] Text source: Decarbonizing Mobility with Liquid Hydrogen, SAE Research Report, 2024.

Author Bio

Matt Moran is the Managing Member at Moran Innovation LLC, and previous Managing Partner at Isotherm Energy. He's been developing power and propulsion systems for more than 40 years; and first-of-a-kind gas, slush, and liquid hydrogen systems since the mid-1980s. Matt was also the Sector Manager for Energy & Materials in his final position at NASA where he worked for 31 years. He's been a cofounder in seven technology-based startups; and provided R&D, engineering, and innovation consulting to several hundred organizations. Matt has three patents and more than 50 publications including his online Cryogenic Fluid Management guide and Decarbonizing Mobility with Liquid Hydrogen SAE report. He has created and taught liquid hydrogen courses, webinars, and workshops to global audiences.
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Friday, May 23, 2025

LH2 Newsletter (Issue 2025.2)


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Thursday, May 8, 2025

Cryogenic Hydrogen Report from HII

Download full report


The Hydrogen Innovation Initiative has released an outstanding resource that can be accessed at the above caption link. Kudos to the individuals who created this well-done primer! Some quick notes on a few of the topics based on my experiences [1]:

3.1 Hazards. The high diffusivity of H2 combined with 20 m/s rise rate in air at ambient temperature makes leaks much less hazardous than many fuels in some regards. My three mantras for all H2 systems are: prevent leaks, provide ventilation, and eliminate ignition sources. It's worth noting that the H2 lower flammability range in air is not much different than methane (natural gas); and it's detonation lower limit range is more than 3 times greater than methane. LH2 pools should only occur in catastrophic accidents and do not last long in practice. Resulting cold vapor clouds are transient but a serious hazard until they warm and rise. For ambient temperature H2, there are no flammable clouds only flammable leak source jets. 

3.2 Ignition consequences. Infrared (IR) detectors and cameras should be used to detect and check for any ignited H2 leaks or flare stack operations (although, they are generally visible at night or in dark locations). The low thermal radiance compared to other fuel fires is due to the lack of soot particles and allows first responders to get closer to the flame if needed.

3.3 Pressure system hazards. Phase change from liquid to vapor at 1 bar results in a 53-fold increase in specific volume which can quickly cause overpressure in an improperly designed or operated LH2 system. The 1:848 expansion ratio is a bit misleading since it assumes the GH2 warms to ambient which would take quite a while to occur in a properly insulated vessel or pipeline. BLEVE is an interesting topic. I've run many thousands of LH2 tests over the years with significant flashing occurring in a receiving tank or vent line exit and never saw any evidence of it. The conditions where it may happen seem to be uncertain at this time.

3.4 Cryogenic hazards. In a properly designed and operated LH2 system, cold burns, hypothermia, and asphyxiation are extremely unlikely. But they must be guarded against like any other hazard. Proper piping and component design and insulation; no enclosed spaces where hydrogen can accumulate; and personal protective equipment (PPE) for any personnel who may be exposed to cryogenic surface during maintenance, etc. Also worth noting: although H2 is an asphyxiant if enough oxygen is displaced, it is not toxic. In fact, breathing gas mixtures for deep diving have used H2. RPT seems similar to BLEVE - a possible scenario but not proven for any specific conditions yet.

4.2 Component level design. Common insulation systems for LH2 include a vacuum jacket with insulation in the vacuum such as MLI, glass bubbles, perlite, or various aerogel formulations. Foam is only appropriate for launch vehicles or potentially other "load-and-go" high consumption applications that can tolerate the poor thermal performance (none currently outside of the space industry that I'm aware of). There is some recent R&D for non-vacuum LH2 insulation that has not been publicly tested or quantified yet. Until it is, vacuum jackets for any LH2 system vessel, transfer piping, and components in contact with the LH2 are a must unless you build rockets (or something with similar requirements). A common MLI construction is layers of double aluminized mylar with dacron netting between them. Approximately 30 layers with a thickness of 2.5 cm can get below 1 W/m^2 heat flux between 300 K and 20 K surfaces in a hard vacuum. Nothing provides near zero conductivity, unfortunately, but MLI in a hard vacuum is the best performing option.

5 Material considerations. While some materials become more brittle at LH2 temperatures (e.g., carbon steel, most plastics, most body-centered cubic metals), others retain their ductility (e.g., aluminum alloys, austenitic stainless with > 7% nickel, and most face-centered cubic metals). However, yield and ultimate strength actually increase generally for most solids; while elastic modulus and fatigue strength varies. Also worth noting is that many material and thermal properties of solids change in a highly nonlinear fashion as a function of temperature in the cryogenic range. This results in the need to integrate properties such as thermal conductivity and specific heat over the temperature range of interest when performing design calculations or modeling. A good deal of historical cryogenic materials testing was done and compiled by NASA, Purdue, NBS/NIST and other sources in addition to the ones mentioned. Coupon sample testing of any new materials, alloys, or processes is critical (especially any additively manufactured structures).

References


Author Bio

Matt Moran is the Managing Member at Moran Innovation LLC, and previous Managing Partner at Isotherm Energy. He's been developing power and propulsion systems for more than 40 years; and first-of-a-kind gas, slush, and liquid hydrogen systems since the mid-1980s. Matt was also the Sector Manager for Energy & Materials in his final position at NASA where he worked for 31 years. He's been a cofounder in seven technology-based startups; and provided R&D, engineering, and innovation consulting to several hundred organizations. Matt has three patents and more than 50 publications including his online Cryogenic Fluid Management guide and Decarbonizing Mobility with Liquid Hydrogen SAE report. He has created and taught liquid hydrogen courses, webinars, and workshops to global audiences.
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Storage of Liquid Hydrogen


LH2 Self Pressurization Test Data, Modeling, and Thermodynamic Behavior [1]

Mobility applications, as well as the infrastructure systems used for fueling operations, require hydrogen storage. Choosing the appropriate hydrogen storage option is driven by system requirements. This process uses a holistic approach that also addresses the local regulatory framework and policy priorities. 

Volumetric storage density and mass fraction are key parameters for mass- and volume-limited mobile applications. Conversely, mass fraction is generally not a driver for stationary fueling, ground support equipment, and long-term storage.

Stationary LH2 storage dewars of various sizes along with the applicable codes and standards are well established. Mobile LH2 storage is less mature and will likely be subject to different certification processes depending on the type of vessel, materials, design details, and application.

Distribution options for LH2 range from long-distance transport to onsite production and liquefaction. Capital and operational costs of the delivery infrastructure drive profitability and subsequent investments. Standardization and interoperability must evolve to bring down costs and accelerate growth.

Thermal management of LH2 and mitigation of boil-off throughout the delivery pathways is critical to minimizing hydrogen loss and associated costs. Identifying the appropriate options to mitigate boil-off losses requires systems engineering to identify the best trades for a particular use case [2].

References

[1] Image source: Liquid Hydrogen Systems Course, 2025.
[2] Text source: Decarbonizing Mobility with Liquid Hydrogen, SAE Research Report, 2024.

Author Bio

Matt Moran is the Managing Member at Moran Innovation LLC, and previous Managing Partner at Isotherm Energy. He's been developing power and propulsion systems for more than 40 years; and first-of-a-kind gas, slush, and liquid hydrogen systems since the mid-1980s. Matt was also the Sector Manager for Energy & Materials in his final position at NASA where he worked for 31 years. He's been a cofounder in seven technology-based startups; and provided R&D, engineering, and innovation consulting to several hundred organizations. Matt has three patents and more than 50 publications including his online Cryogenic Fluid Management guide and Decarbonizing Mobility with Liquid Hydrogen SAE report. He has created and taught liquid hydrogen courses, webinars, and workshops to global audiences.
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Friday, May 2, 2025

Large-Scale Export/Import of Liquid Hydrogen

Export terminals at the Port of Duqm are part of an integrated hydrogen ecosystem envisioned for development in Oman by Hydrom [1]. (Credit: Oman Observer)

I was recently asked to provide feedback on the Oman-Europe liquid hydrogen corridor initiative by the global director of hydrogen at a leading multinational manufacturer of LH2 systems. Thought this might be of interest to others in the the hydrogen community. Below are the questions posed (in bold italic) along with my responses.
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