Hydrogen Workforce Needs

Photo credit: David Blekhman

Yesterday I gave an invited presentation on liquid hydrogen in aviation spotlighting some of the organizations and individuals at the forefront of hydrogen aircraft flight testing, engine development, and airport operations. This will also be the topic of a longer discussion and Q&A for the December 3rd Mission Hydrogen webinar.

The presentation slides along with supplemental content and hyperlinks to more details are available in the "Aviation" briefing at https://h2sage.com. Free registration for the Mission Hydrogen webinar is available here: https://mission-hydrogen.com.

Hydrogen Workforce Needs

The event held on November 18th at the Ohio Aerospace Institute (OAI) was a second in-person gathering supporting the DOE project on hydrogen workforce needs led by the University of Toledo (UToledo). Andrew Gyekenyesi of OAI and Mark Mason of UToledo kicked off the event setting the stage for the project context, progress, and key insights. Regional survey results were then presented by Kevin Cranick of Workforce Intelligence Network.

Some themes that continued to be built upon as the day progressed included:

• Creating the right balance of workforce training and upskilling building on foundational community college and university curricula and supplementing with hydrogen specific knowledge depending on the needs of specific job roles.
• Credentialing programs, short courses, trades upskilling, and other shorter training opportunities to provide key skills quickly and tailored to various industry sectors and applications.
• The need to create a pipeline of education and awareness programs in secondary (high schools) and perhaps earlier, as well as activities that provide broader public awareness directly or indirectly to parents and other local community members.

Industry Perspectives

My aviation presentation was part of the industry portion of the event to provide examples of how hydrogen systems are being developed, deployed, and operated. Mark Haberbusch of NEOEx Systems described some of their new systems that liquefy hydrogen (electrolytically produced from microgrid renewables or from other sources), and refuel long range drones with liquid hydrogen.

David Perzynski followed with a portfolio of initiatives under development at Honda for hydrogen vehicles, engines, and other applications. Nick Vargo of Babcock & Wilcox finished up the industry portion with a description of their chemical looping technology for producing low-carbon hydrogen from various hydrocarbon feedstocks using engineered FeO particles.

Education and Training Perspectives

The afternoon session started with a presentation by Pat Hufnagel-Smith of Creative Links summarizing some findings from her work on building a resilient energy workforce amid uncertainty. Later presenters confirmed that her publication on this topic is the best available and a gold standard.

Anil Bika of the University of Delaware presented information on some of the hydrogen initiatives, electrochemical engineering program, high school programs, and key industry collaborations at the Center for Clean Hydrogen. The importance of building an ecosystem of diverse stakeholders was evident.

David Blekhman of California State University, LA followed with highlights of the impressive array of projects, sustainable energy curricula, fueling stations, hands-on internships, and industry collaborations he has developed over many years as Technical Director of the Hydrogen Research and Fueling Facility.

Tiffany Howard of South Louisiana Community College provided a thought provoking final presentation on community college strategies and tactics during times of economic stagnation drawing on her experiences in a variety of roles and insights from previous technology trends in driverless trucking and broadband communications.

Panel Discussions and Networking

Sujata Shetty of UToledo led a panel discussion amongst the afternoon presenters that included audience thoughts and insights. Although it covered a great deal of themes, a few takeaways from memory:

• Supplemental and complementary training and curricula related to hydrogen that can build upon foundational certifications and degrees may be the best approach (i.e., rather than specific "hydrogen" degrees)
• Uncertainty in public policy, economic, and other factors requires developing adaptable and robust training and upskilling options
• Attracting, training, and retaining an emerging and skilled hydrogen workforce requires addressing multiple worker needs including aspirations for meaningful work, career stability, personal growth, and quality of life.

In addition to the scheduled talks and presenters, I enjoyed catching up with existing colleagues along with some new and inspiring contacts across the economic development, industry associations, and other key actors in the hydrogen and sustainable energy ecosystem. 

Bill Whittenberger and Linda Buckosh of the Ohio Fuel Cell and Hydrogen Consortium continue to advocate for hydrogen-related businesses to various stakeholders within the state and well beyond. Keri Zipay of TeamNEO and Jing Lyon (past interim CEO at Brite Energy) are economic development champions who help make critical connections and assist new businesses in the region.

An unexpected bonus was meeting Veronica Vaca of Cobra Industrial Activities who is focused on geologic hydrogen (both naturally occurring and stimulated by selected fluid injection). This is a topic that is rapidly gaining interest from investors and industry, and has the potential to significantly lower hydrogen supply costs for various use cases.

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.

H2 Sage™ and an Engineer's Dilemma

A couple months ago, I started working on a full stack web app for hydrogen systems with an emphasis on liquid hydrogen. The goal was to provide an online resource to learn, strategize, design, analyze, develop, build, operate, and manage these systems.

Above are some screen shots from the current development version after more than 150 hours of effort. Have learned a great deal about modern software-as-a-service development in the process. However, progress has been slower than planned which prompted me to take a step back and consider alternative approaches.

In only a half day, I was able to replicate everything represented in the first image above in a new page on my website. Another half day was required to produce the Python code for several convection heat transfer conditions and associated calculations. It will take a bit more time to put together a display for the code results, but far less than the full stack web app approach.

Of course, there's much more built into the web app version (e.g., client/server coordination, APIs, hosting service, account management, payment transactions, navigation, user guide, community forum, terms of service, privacy policy, etc.). But is the effort and time to implement all these advanced features a common case of the engineer's dilemma: "perfect is the enemy of good enough"?

So, I'm at a bit of a crossroads about what best serves the intended goal. A more polished web app, or a simpler approach that deploys much faster? Below is a link to the latter for comparison - feedback appreciated.

https://sites.google.com/view/matthewemoran/h2-sage

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.

Hydrogen in Aviation (Myth Busting, Episode 5)

Hydrogen aircraft concept (Airbus); engine testing (Rolls-Royce); and flight tests (multiple)

There is a small cadre of very vocal hydrogen critics with an outsized presence on social media, and media coverage in general. I've written about some of the most common archetypes in a previous hydrogen myth busting post [1]. Yet in a Google Scholar search on "hydrogen aviation", these self-proclaimed experts are nowhere to be found in the ranking of published sources on the topic [2].

Unfortunately, peer-reviewed articles are also not a guarantee of unbiased accurate information as addressed in my recent LinkedIn post on the topic [3]. A contemporary example is an article co-authored by techno-economic and energy analysis experts, but without any apparent input from experts with relevant hydrogen systems experience [4]. As a result, it contains some errors, omissions, and assumptions untethered to real world data.*

In the real world, the increased use of hydrogen in new aircraft development and demonstrations requires a paradigm shift in conventional aviation systems engineering and integration. Unlike sustainable aviation fuel (SAF) options, hydrogen is not a drop-in replacement for legacy aircraft. However, hydrogen is an important long-term solution in terms of performance, environmental impact, many safety aspects, and full lifecycle cost.

This leads to a few key questions. Why is hydrogen being used for aviation? What are the fundamental design drivers for successful implementation? How can lessons already learned from the aerospace sector be incorporated? This blog post is a short introduction to these topics in the hopes of dispelling some of the persistent misinformation that continues to be posted and published on the subject.

Options for Decarbonizing Aviation

The table below summarizes key characteristics of the primary atmospheric greenhouse gases (GHGs), with carbon dioxide (CO2) being the most prevalent in terms of concentration and with an atmospheric lifetime of thousands of years. The global warming potential of these GHGs in the last column has been normalized to CO2. Each of these characteristics are important to keep in mind when assessing the impact of any systems or processes that use or emit one of these GHGs.**

Aviation accounts for roughly 2.5% of all global CO2 emissions and 4% of the global warming to date [5], with CO2 emissions expected to double in 25 to 30 years based on current legacy technologies and predicted growth in air travel according to the FAA.^ These may seem like small percentages in the big picture, but aviation is a difficult industry to decarbonize directly with renewables-based electrification along with other large transportation and maritime applications. There are a few methods for potentially reducing GHGs that are applicable to aviation: SAF, batteries, hydrogen, methane, and nuclear.

SAFs provide a near-term solution for reducing CO2 emissions in existing aircraft as a drop-in fuel. However, the impact on overall CO2 emissions depends on the degree of uptake and these emissions continue to grow over time for most scenarios.^ So, SAFs can help blunt the environmental effects of legacy fuels, but they can't fully decarbonize aviation. In addition, SAFs have some challenges at scale related to sustainable feedstocks, supply chains, and infrastructure build out. Incidentally, some of the most promising formulations use hydrogen as a feedstock.

Batteries are feasible for some electric aviation applications where the impacts to range, payload, and operations due to their low specific energy relative to chemical fuels and their charging requirements are acceptable. Most of these applications are short haul small aircraft flying at low to moderate altitudes using electric motor driven propellers or fans. A fundamental drawback is that batteries weigh the same whether fully charged or fully discharged, so there is no reduction in aircraft mass in flight (or propulsion requirements) common with chemical fuels. And landing is one of the highest energy consumption flight phases, resulting in a hot discharged battery that must be conditioned and recharged before the next flight. This impacts operational turn around time and infrastructure requirements. 

Hybrid electric aircraft concepts can potentially extend the suitable aviation applications using various fuels (including hydrogen) integrated with batteries. Depending on the fuel choice, there are tradeoffs related to technology development required, degree of decarbonization, and other parameters. Advanced hybrid electric propulsion systems are under development by NASA and other organizations that may be promising to commercialize as they reach sufficiently mature technology readiness levels.

Methane, which is the primary constituent of natural gas, and liquefied natural gas (LNG) have been considered and tested for aircraft. But neither are drop-in fuels. In the case of LNG, cryogenic systems similar to liquid hydrogen (LH2) must be developed, albeit at a somewhat higher operating temperature as shown below. Similar to SAF, combustion of methane still produces CO2 emissions, although at a lower rate than legacy fuels. More concerning is un-combusted methane that has 25 times the 100-year global warming potential of CO2. So any leaks, venting, dumping, or other releases of methane anywhere in its journey from extraction or production to consumption represents a powerful GHG gas being added to the atmosphere.

Nuclear aircraft were investigated by NACA and during the early days of NASA. And demonstrations of nuclear powered drones have been reported in recent years by multiple sources. In theory, the performance of these aircraft greatly exceeds any chemically fueled or battery powered vehicle. In practice, use in a non-military application would run afoul of national security, regulatory, and public safety concerns. This is also the reason why nuclear powered naval ships and submarines have been successfully operating since the 1950s, but there is only one currently operating nuclear powered merchant ship.

That leaves hydrogen as the final practical option, which can be used for an unlimited range of aircraft types and flight requirements. A multitude of hydrogen propulsion systems testing and flight tests have been successfully performed by combusting it in jet engines or feeding it to fuels cells for electric motor driven propulsion. Hydrogen is suitable for fixed wing or vertical-take-off-and-landing (VTOL) aircraft of any size currently used, at any currently feasible altitude and range, and with no carbon emissions during operation.

Hydrogen Use in Aerospace

There are two primary reasons to use hydrogen for any aerospace application: superior performance and decarbonization.

Performance is the reason liquid hydrogen has been used for various launch vehicles and rocket stages continuously at large scale and full lifecycle for six decades. Historic examples include: Apollo's Saturn rocket upper stages, Centaur upper stage, and the Space Shuttle. Currently operational examples include: NASA's SLS (see design below); upper stages of the Atlas V, Delta IV, ULA Vulcan, and New Glenn; EU's Ariane 5 and 6; Japan's H-IIA; variants of China's Long March rockets; and India's LVM-3 upper stage.

The specific energy (energy per unit mass) of hydrogen is three times greater than legacy fuels, and along with other energetic properties and characteristics enables its superior performance. This is offset by the low volumetric energy density which requires larger storage volumes compared to legacy fuels. However, fuel cell applications significantly reduce this requirement with more than double the efficiency of conventional combustion engines. Below is a plot illustrating some of these hydrogen properties.

For aircraft, decarbonization is the primary reason for using hydrogen, although performance gains are possible as designs evolve to optimize its usage. The first LH2 aircraft flight testing was done in the 1950s by NACA/NASA, and a dozen more hydrogen powered aircraft have flown as of 2024.

Fuel cell power and propulsion systems only emit water vapor during operation and are currently limited to altitudes where propellers can be used. However, internal combustion engines (ICE) can cover the entire aircraft size range (small piston to jet engines) and can operate at any altitude currently feasible with legacy aircraft. In fact, hydrogen ramjets and scramjets can operate well above legacy aircraft altitudes.

It's important to note that all combustion engines produce nitrous oxides (NOx) due to the disassociation of air at high temperatures. However, the wide oxygen-fuel (O/F) ratio possible with hydrogen permits very lean mixtures that can decrease NOx much more than legacy fuels or SAF.

There is much too be learned in implementing hydrogen aviation from the aerospace-adjacent space industry. Systems, integration, infrastructure, safety, components, supporting technologies, supply chains, and a host of other challenges have long ago been solved in the space industry. Adapting all of it to new industry sectors requires good systems engineering, sound business models, capital investments, infrastructure build out, scaling for cost reductions, and supportive policy and regulatory environments. All the enabling technology is already available.

When all lifecycle costs are included, hydrogen is an economically competitive investment in our future. As it scales, further cost reductions will occur as they do with any new technology shift. This has occurred with solar and wind renewables, just as it did with the shift to natural gas, and the shift from coal to oil before that, and the shift from wood to coal before that. It is the natural economic evolution of new energy paradigms [6].

Valid comparisons to legacy fuels must include their costs associated with: exploration of underground sources (including "dry well" and other abandoned costs); extraction; storage; delivery to refinery; refining; distribution; fueling depots and stations; legacy subsidies; and casualty losses and public health impacts from exposure to toxic fuels, fumes, smoke/soot, polluted air and water, accidents, and all the aggregated effects of GHG emissions. Along with the outlays over the past 100+ years (private and public) associated with putting all the existing infrastructure in place for fossil fuels.

Hydrogen Systems Considerations

For aviation and most other industry sectors transitioning to hydrogen, there are a few key initial design drivers to consider, particularly for LH2: volumetric density, systems integration, cryogenic engineering, operations, and safety.

The comparatively low volumetric density of hydrogen is resolved in the systems engineering and integration of the aircraft. For legacy aircraft, innovative designs and packaging of hydrogen tanks is required. This can result in less volume available for payloads or passengers, longer and/or wider fuselages, storage outside of the fuselage, or other methods to accommodate the volume required.

Larger tanks that can result in increased drag for legacy aircraft designs are a relevant consideration, although many aircraft have successfully flown with enormous outer mold line volumes in order to achieve overall vehicle and mission performance criteria [7]. New VTOL and fixed wing aircraft designs optimized around hydrogen can actually improve aerodynamic performance. Lifting bodies and flying wing configurations are examples where the volume requirements become much more easily integrated within the fuselage [8].

Therefore, the combination of higher specific energy but lower volumetric density of hydrogen relative to legacy fuels are primary parameters to optimize in aircraft design. Lower fuel mass requires less lift which can be traded against greater payload and/or longer range. Larger fuel storage volumes require holistic integration within the aircraft to minimize the impact on drag and maximize aircraft performance and capabilities.

Systems engineering and integration combined with cryogenic engineering best practices also plays an important role. A portion of the energy expended to liquefy hydrogen can be recovered for better overall system efficiency [9]. Examples include: pressure building systems for zero-power pressurization; heat rejection from other subsystems; thermal protection of structures exposed to high temperatures; cooling of superconducting components; Joule-Thomson cooling; vapor-cooled shields for reducing heat loads; para-to-ortho conversion cooling; and other methods.

Existing mature cryogenic engineering technologies also enable any LH2 storage and deliver system to have zero boil-off losses. Every LH2 storage system has a characteristic natural boil-off rate profile depending on the size, environment, operations, fill level, and other variables.^^ In all cases, boil-off gas losses can be driven to zero with a combination passive, hybrid, active, and operational techniques. Claims of unavoidable boil-off losses with LH2 systems are false. All boil-off losses are avoidable with proper system design [10].

Changes to aircraft operations, and required airport infrastructure, are also valid considerations [11]. Below is a notional example of how onboard LH2 storage is affected by the acceleration and thermal environments during key aircraft operations. In addition to onboard systems that properly manage LH2, ground support systems must also be in place to support fueling and other associated activities [12]. Various organizations and standards working groups are actively addressing these aspects in preparation for the decades of development required to fully build out the infrastructure [13].

Safety is a paramount consideration with any fuel or energetic system, and hydrogen is no exception. Many codes, standards, training, and certifications are already in place; and many more are under development to address specific use cases and industries. Below is a comparison of key safety relevant properties for hydrogen and natural gas (methane). A few implications that may not be obvious on initial inspection:

• A given volume of methane has more stored energy for detonation than hydrogen under identical conditions; and its lower bound detonation limit in air is less than one-third that of hydrogen
• While both gases are lighter than air at ambient temperatures, hydrogen rises much faster (20 m/s or 45 mph) and diffuses much more rapidly in air
• The lower flammability limit in air (which any safe system is designed to stay well below) and the autoignition temperatures for the gases are not much different
• However, hydrogen has a much lower ignition energy, much higher upper flammability limit in air, and much higher flame speed

So which fuel is safer? It depends on the situation.# The same can be said for comparing legacy aviation fuels with hydrogen, because each fuel behaves very differently. In a mid-air collision or an emergency landing where the fuel storage is breached, hydrogen (in liquid or gas phase) would be vaporized, gone/diffused, ignited upward, or some combination thereof. And with none of the toxic fumes, smoke/soot, persistent burning pools of spreading liquid, or extended exposure to high temperatures that jet fuel produces.

On the other hand, an undetected fuel leak and potential ignition event is a generally lower risk for jet fuel than it is for hydrogen. However, hydrogen is nontoxic and can be safely breathed as long as its concentration is below asphyxiation levels. Definitely not the case for any legacy aviation fuels. Bottom line: every potential hazard and operational situation requires careful consideration while keeping in mind the unique properties and behaviors of the specific fuel in question.

The Path Forward

Every new energy paradigm shift in history (and every other major technological disruption) has occurred due to market adoption within a supportive policy environment by innovating individuals and teams developing systems and products in the real world. Not on social media. Not in general media opinion pieces or news coverage. And not in peer reviewed articles that ignore information that doesn't fit the predetermined narrative of the authors.

If we had relied on the talkers during previous energy paradigm shifts, we would still be huddled around wood and brush fires. Afterall, a technoeconomic analysis before the industrial revolution could have easily showed that the complexities and costs of extracting fossil fuels and transitioning to their use made no sense compared to burning cheap available wood. And if we rely on today's talkers and delay addressing the existential threats of rising GHGs, public health impacts, and pollution, we will end up dealing with much larger fires and many more calamities at a scale unprecedented in human history.

Footnotes

* For example: ignoring flight demonstrations and testing, alternative aircraft concepts, hydrogen systems state-of-the-art, cryogenic systems integration, propulsion dynamics, regulatory and certification pathways, infrastructure assessments, energy density trades, thermal management, cost projections, etc.

** Note: the so-called 'indirect greenhouse gas' effect of hydrogen is an unproven hypothesis based on unverified assumptions and no atmospheric data at scale. And initial studies into the contrails produced by hydrogen aircraft indicate they dissipate quicker than legacy aviation fuel contrails.

^ The website that documented this information appears to have been taken down by the current administration (https://www.faa.gov/sustainability).

^^ There is no standard value or accurate rule of thumb for estimating natural LH2 boil-off rates despite many sources that attempt to claim otherwise (which is a clear sign of someone lacking experience in this domain).

# Paradoxically, the most infamous historical hydrogen incident would have been much worse with any other fuel under similar conditions: store the fuel in an enormous fabric container with a highly flammable coating; suspend 97 people from it 200 feet (60 m) above the ground; have more people underneath it; allow a lightning strike to ignite the flammable coating; record it with a 1930s era black & white motion camera (that won't record hydrogen flames in daylight, and all the hydrogen is out of the frame within 2 seconds anyway). In the case of hydrogen, it did not detonate nor apparently even ignite any significant amount since there were no water droplets. And 62 of the 97 people onboard survived, with one casualty on the ground. What would be the outcome of repeating that scenario with any other fuel? Or with batteries?

References

[1] "Myth Busting (Episode 4): Hydrogen Haters", LH2era.com, Oct 26, 2023.

[2] "Hydrogen Aviation" Google Scholar search.

[3] Misinformation Hydrogen Zombies, LinkedIn post, Jun 27, 2025.

[4] "Realistic roles for hydrogen in the future energy transition", Johnson, et al., Nat. Rev. Clean Technol. 1, 351–371 (2025).

[5] "What share of global CO₂ emissions come from aviation?", Ritchie, Apr 8, 2024.

[6]  "Why All Hydrogen Cost Projections Are Wrong", LH2era.com, Aug 5, 2023.

[7] "List of large aircraft", Wikipedia

[8] "Lifting body", Wikipedia

[9] "Why Liquefy Hydrogen?", LH2era.com, Jun 4, 2025.

[10] "Hydrogen Myth Busting (Episode 3)", LH2era.com, Apr 16, 2023.

[11] "Decarbonizing Mobility with Liquid Hydrogen", SAE Research Report, 2024.

[12] "H2-powered aviation – Optimized aircraft and green LH2 supply in air transport networks", Hoelzen, et al., Applied Energy, Vol. 380, 2025.

[13] "Hydrogen Fueling Stations for Airports, in Both Gaseous and Liquid Form", SAE International, issued Nov 11, 2024.

All graphics are from: Liquid Hydrogen Systems Course, Moran Innovation LLC, 2025.

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.

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

[1] Liquid Hydrogen Systems Course, 2025.

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.

Safety with Liquid Hydrogen

Relative to conventional fuels, hydrogen has a wider flammability range in air (4–75%), higher permeability through some materials, and a lower ignition energy (0.02 mJ). These characteristics make it vital to provide adequate ventilation, prevent leaks, and eliminate ignition sources in any hydrogen system design and operation. System monitoring and detection is important to ensure that all safety precautions are active and operating as intended. 

The very rapid 20 m/s rise rate of gaseous hydrogen in air under ambient conditions greatly aids with ventilation and dilution. Hydrogen also has an auto-ignition temperature of 585°C, which is higher than most fuels. Hydrogen is colorless, odorless, and not toxic to breathe. However, low oxygen detection is needed anywhere hydrogen may accumulate near personnel since asphyxiation is possible if insufficient oxygen is available.

When combusted, hydrogen produces no smoke or soot, which eliminates associated inhalation risks common with fossil and other hydrocarbon fuels. The resulting flame also produces much less radiant energy compared to hydrocarbon fires, thereby reducing the zone of potential heat damage or burns. A hydrogen flame is nearly invisible under daylight conditions, requiring infrared sensors or cameras for detection. At night, the flame is pale blue in appearance. For all hydrogen systems, emergency and fire response planning and coordination is a critical consideration.

The use of LH2 introduces additional safety concerns beyond gaseous hydrogen due to the temperature extremes and phase change characteristics inherent in cryogenic fluid systems. Personnel training, appropriate protective clothing, human interface designs, and safe operations are key to mitigating frostbite and other physiological risks. Appropriate equipment design that eliminates the possibility of human contact with cryogenic surfaces is preferable whenever possible. Exclusion zones, caution and warning systems, safety sensors, and approved operational procedures further mitigate risks to personnel.

The large temperature ranges in cryogenic systems require careful materials selection and design to accommodate differences in thermal expansion and contraction. Phase change from liquid to vapor (and sometime the reverse) occurs throughout a LH2 system, resulting in potential rapid pressure changes in isolated volumes. This must be addressed with appropriate design, operations, and pressure relief devices. If maximum vent relief flow rates are high enough, flaring may be required.

Mitigation of ice buildup is necessary where it may cause key components to not operate properly or create other hazards. Likewise, prevention of oxygen condensing out of the air is addressed with proper insulation on any surfaces that may reach low enough cryogenic temperatures. Any LH2 spills will begin to immediately vaporize and rise as the vapor warms. However, the initially cold hydrogen vapor will be denser than air and can result in temporary regions of high concentration near the ground.

Material selection for hydrogen service must address the design and operational requirements for strength, ductility, fatigue, permeability, and other material properties. Approved cleaning processes must be followed to ensure that unacceptable contaminants are not introduced to the system from materials. Purity levels of the hydrogen are generally dictated by the fuel cell specifications or other feed requirements. Purging and inerting of the assembled system is required for various operations to prevent the introduction of air or other contaminant fluids.

Retrograde US Energy Policy

"The biggest story in the data is the dramatic growth of [US] solar energy, with a 30 percent increase in generation in a single year, which will allow solar and wind combined to overtake coal in 2024." [1]

This pie chart and quote may be one of the last bits of promising US energy news we'll get for the next few years. Many colleagues have asked my opinion about the prospects for hydrogen in the US under the new administration. Here's a breakdown of what we already know, and my guess about what's to come.

Federal Energy Policy

The new federal energy policy can be summarized as a huge step backwards that prioritizes oil and gas while demonizing intermittent renewables [2]. This ignores the fact that solar and wind are the lowest cost power generation sources to bring online and operate, which is the primary reason they have grown so rapidly in recent years.

Mitigation of greenhouse gases and pollution are existentially crucial additional benefits of renewables, making them the logical focus for growth from both an economics and environmental perspective. But propaganda trumps cost of electricity, public health, casualty losses, and the future quality of life for coming generations in the current administration.

The new secretary of energy has parroted this policy, with additional emphasis on liquefied natural gas (LNG) exports from the US. LNG is 85-95% methane, which is a 25 times more potent greenhouse gas than carbon dioxide over 100 years (85 times more over 20 years). Gas leaks and intentional venting are prevalent sources of methane emissions from production, transport, and end use of LNG.

What About Hydrogen?

There is no mention of hydrogen whatsoever in any US energy policy documents released by the new administration. So what does that mean for federal policy regarding hydrogen? Let's connect some dots by enumerating a few key benefits of hydrogen in the energy sector:

1. Hydrogen produces no greenhouse gases and no pollution of any kind when used to produce electricity with fuel cells. If burned in a turbine or other combustion engine, it produces some NOx (as all combustion processes do) that can be minimized with various design and operational parameters.
2. Hydrogen can store energy at nearly unlimited scale from intermittent renewables when excess generation capacity is available, and be used to generate electricity when demand exceeds generation capacity.
3. Hydrogen's unparalleled specific energy relative to any other conventional fuel enables high performance sustainable solutions across multiple mobile and transportation sectors (e.g., aviation, rail, maritime, trucking, etc.)
4. Hydrogen provides unique energy resiliency and eliminates fuel logistics dependencies for remote or isolated regions.

Note that none of the above benefits are aligned with the new federal energy policies. Nor were they eight years ago when we saw this energy policy disaster unfold the first time around. Looking back at that timeframe may help make a clear-eyed assessment of what's to come.

The Path Ahead

Within this new reality, what is the future for hydrogen in the US? Regrettably, here are my predictions:

• Federal funding for hydrogen programs, including the hydrogen hubs, will be largely gutted. One potential exception is military applications where hydrogen addresses strategic defense and national security challenges that no other approach can match.
• States and local policies and funding will help in a few US regions. California will remain the hydrogen hotbed it has been for many years. Hawaii, New York, Pennsylvania, and parts of New England also have or may provide supportive policies for hydrogen. Texas will be a wildcard since there is much in place for hydrogen production, but may have fractured policies depending on the area (e.g., Gulf coast vs rural areas). However, many other states and locales already have policies that are hostile toward renewables and hydrogen, and will be emboldened to double down on derailing permitting and similar tactics with the new federal policies.
• Private sector funding for hydrogen systems and products has been extensive in some industry sectors and regions. Many of these hydrogen applications have demonstrated performance and economic viability at various commercial readiness levels. It's unlikely that private investors will walk away from sunk cost investments if there is an opportunity to get a reasonable return. The challenge is which global markets are the best targets if most of the US is off the table, which leads to my final prediction.
• Global regions will likely stay the course, or even accelerate hydrogen plans, as the US backs away. China will build on its lead as the largest producer and user of hydrogen and associated systems. The European Union, United Kingdom, India, South Korea, Japan, and Australia may find increased interest in new hydrogen projects in their regions with the drying up of US funds and incentives. The same for other countries and regions with established and emerging hydrogen programs such as Canada, South America, Middle East, Africa, and other countries in the Asia and Indo-Pacific regions.

[1] John Timmer, Ars Technica, Jan 27, 2025.

[2] Executive Order, Jan 20, 2025.

[3] Secretarial Order, Feb 5, 2025.

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 break-through liquid, slush, and gaseous hydrogen systems since the mid-1980s. Matt was also the Sector Manager for Energy & Materials in his last position at NASA where he worked for 31 years. He's been a co-founder in seven technology startups; and provided R&D and engineering support to many organizations. Matt has three patents and more than 50 publications including the Cryogenic Fluid Management series. He also teaches courses, workshops, and webinars on liquid hydrogen systems.

Cryogenic Hydrogen Thermal Design Options

A key storage consideration for liquid hydrogen is the vaporization rate caused by environmental heat loads, often referred to as boil-off. The above graphic shows some of the established methods for mitigating or eliminating boil-off categorized by the input power required [1].

Passive techniques require no input power and include design and material selection for insulation, structural supports, piping, and other tank interfaces that minimize heat transfer to the inner tank wall. Hybrid methods require some input power for valve actuation, mixers, pumps, or other components to reduce the boil-off rate. 

Finally, active techniques require power input for cryo-refrigeration or densification processes. Depending on the concept of operation for the system, application of the appropriate combination of these methods can minimize or eliminate boil-off losses [2].

Hydrogen Storage Options

The most common commercially available storage options along with some of their key characteristics are shown above [1]. Each of these methods has advantages and disadvantages that are critical considerations for selecting the best storage method for a given system and use case.

Low-to-moderate pressure storage in salt caverns or other compatible underground locations enables large quantities of gaseous hydrogen to be stored for long periods of time. Electrical energy input is required for a blower or compressor to inject the hydrogen and buffer gas underground at the desired storage pressure. This approach relies on the necessary local geology as well as connection to a gaseous distribution system similar to natural gas infrastructures. A hydrogen liquefaction plant can also be sited nearby using the underground hydrogen storage as feedstock after removal of the buffer gas.

Material-based or solid-state storage is a broad category that encompasses methods to store hydrogen in a matrix material via microscale adsorption or chemical absorption. Many materials and methods have been developed, with metal hydrides currently the most common type in commercial use. Thermal energy is generally required for the solid-state storage reaction to occur as adding hydrogen is exothermic requiring cooling, and removal is endothermic with heat addition. Metal hydride systems are generally better suited to stationary applications due to their low mass fraction and should be installed where low-cost process heat and cooling are available or low pressure is especially important. However, newer technologies using lightweight matrix materials such as aerogels may hold promise for some mobility applications.

Compressed gaseous hydrogen storage requires electrical energy to create the high pressures required. Cooling is also needed to bring the gas stream back down to ambient temperature due to the heat of compression. Composite overwrap pressure vessels (COPV) designed to withstand the high pressures are commercially available at 350 or 700 bar. Initial mobility demonstrations with hydrogen often use COPV storage, and for some applications this option is sufficient to meet the system goals. For many mobile applications, however, the volumetric energy density and mass fraction of compressed hydrogen storage is too low to meet performance requirements.

Cryogenic LH2 has nearly double the volumetric storage density of 700 bar compressed hydrogen at ambient temperature, and along with low-pressure storage conditions enables a much higher mass fraction. For this reason, many transportation applications transitioning to hydrogen are storing or planning to store in cryogenic liquid form. The primary electrical energy input required for LH2 storage is the liquefaction process. As previously mentioned, LH2 has been the primary storage and distribution method in the space industry for many decades.

In aviation, H2Fly demonstrated LH2 onboard storage during successful flight testing of their small demonstrator aircraft. ZeroAvia and Airbus have publicly shared their LH2 design plans for new aircraft. Nikola and Hyzon have demonstrated long-range truck routes with LH2, and First Mode has demonstrated hydrogen in a large mining truck. Operational mobility systems using LH2 include Hyundai Rotem trams and marine vessels from multiple companies.

Cryo-compressed hydrogen is another option that has intriguing advantages for some mobile applications. In this supercritical storage state, the hydrogen is compressed at cryogenic temperature resulting in higher potential volumetric density compared to LH2 storage. However, the mass fraction is generally less than LH2 storage systems due to the need for thicker walled vessels to withstand the higher pressures. The U.S. Department of Energy (DOE) has funded development of this technology over many years, and it is now being commercialized by Daimler Truck, Verne, and others. Daimler has also developed a ‘subcooled’ transfer process that can fuel a truck with 80 kilogram of hydrogen in 15 minutes or less without a return vent line resulting in onboard cryo-compressed storage. [2]

Focusing on a Hydrogen Future

You may recognize the above graphic as a slightly modified version of the Eisenhower decision matrix, a powerful tool for managing day-to-day activities. I've found it can also be useful for business or career strategy by re-labeling the axes "revenue" and "impact". The familiar resulting quadrants help identify priorities for executing, investing, delegating, and deleting.

In a recent talk, Thomas Friedman spoke about two unprecedented "supercycles" we are in the midst of: climate change and AI. The first is an existential threat; and the second could help us solve the first one, or become an existential threat itself, or both.

Within that sobering context, here's where my company is heading in 2025:

• Liquid hydrogen systems development (execute): In my previous post, I mentioned the hydrogen microgrid project, LH2 drones and automated fueling systems, and NASA lunar lander development activities my company supports. These are core company projects, and the first two will remain top business priorities in 2025 with the goal of full scale demonstrations.
• Knowledge transfer (invest): I've already invested a good deal of time into creating various resources and tools for developing liquid hydrogen systems, most of them freely accessible on my Training page. Have also contributed to LH2 related standards and guidelines development, and will continue those efforts. Next, I'll be creating, training, and fine-tuning a hydrogen AI agent called H2 Sage using: curated public domain data; my intellectual property data from 40 years of hydrogen technology and systems development; and the most powerful LLM APIs available (e.g., OpenAI o3 and future frontier models).
• Space projects (delegate): This is a very difficult pivot for me. I worked directly for NASA for 31 years, and continued supporting them on various contracts for another 9 years. Have also done space related work for DOD and multiple private sector organizations over that timeframe. But it's time to let my younger and more talented colleagues at NASA, its contractor teams, and commercial space to continue forward in this inspiring and important area without me.
• Talkers vs doers (delete): Not long ago, only chemistry teachers and professionals working in just a few industry sectors talked about hydrogen. Now almost everybody - especially on social media and from various news outlets - seems to have an opinion on the topic. On one end of the "talker" spectrum are hydrogen haters (see my old post), and on the other end are those pitching hydrogen concepts they cannot deliver. Both ends, and many talkers in between, often have little or no actual experience with hydrogen. And they are impeding our progress toward addressing climate change with misinformation and predictable failures. We need to support the hydrogen doers and ignore the hydrogen talkers.

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 break-through liquid, slush, and gaseous hydrogen systems since the mid-1980s. Matt was also the Sector Manager for Energy & Materials in his last position at NASA where he worked for 31 years. He's been a co-founder in seven technology startups; and provided R&D and engineering support to many organizations. Matt has three patents and more than 50 publications including the Cryogenic Fluid Management series. He also teaches courses, workshops, and webinars on liquid hydrogen systems.

Liquid Hydrogen (LH2) Gifts from Santa in 2024

Image credit: Matt Moran, Moran Innovation LLC

It was a busy 2024 for my company, Moran Innovation, with implementation of all the capabilities shown above on Santa's list into new LH2 systems for NASA, DOD, and private sector customers. Also, lots of activities related to training, publications, and standards development. Here's a few highlights with hyperlinks to information that may be of interest to the hydrogen community:

 

• Decarbonizing mobility with liquid hydrogen. Published an SAE Edge™ report on this topic with contributors from multiple industry sectors and global regions. Discussed it at the WCX SAE Knowledge Bar and a SAE The Mobility Frontier webinar.
• Hydrogen-based microgrid. Completed the first phase of adding hydrogen capability to the PEARL microgrid in Honolulu. The expanded multifunctional operations will include production of hydrogen from solar-powered electrolysis, compressed storage, power generation from fuel cells, and in-tank liquefaction for unlimited LH2 storage time (dormancy) and offtake fueling.
• LH2 drones. Continued support of NEOEx Systems liquid hydrogen drone development with automated fueling and on-demand full lifecycle production and liquefaction. Their systems eliminate the need for LH2 distribution, transport, delivery, and ground support storage.
• Airport hydrogen fueling standards. Continued participation in the SAE AE-5CH Hydrogen Airport Taskgroup which published the first global guidelines for airport hydrogen refueling stations.
• Vacuum-jacket piping guideline. Began development of guidelines for vacuum insulated piping for cryogenic applications with a small group of fellow experts.
• NASA lunar landers. Completed the fourth year of providing cryogenic fluid management subject matter expertise to the NASA Human Landing System program and other contracts related to LH2 and other cryogens including zero boil-off systems.
• Courses, webinars, and workshops. Completed the first ever webinar series solely dedicated to LH2 resulting in 13 monthly webinar sessions during 2023-2024. Just released an online, on-demand LH2 systems course that will preview a new lecture every month in 2025 for free. Taught the hydrogen fundamentals portion of the AIAA/HYSKY Advanced Hydrogen Aerospace Technologies and Design course, and did other training and workshops at various conferences and venues. Details can be found on my website Training page.
• Global LH2 topics. Continued managing the Global LH2 Systems LinkedIn group that I started last year for sharing news and other topics relevant to the worldwide LH2 community.

The global momentum with LH2 systems development across many industry sectors and regions is very encouraging. Significant capital investments are accelerating the transition to hydrogen to meet our energy needs while eliminating the sources of damage to our environment and public health caused by burning fossil fuels. This transition also provides energy security, resiliency, and sustainability; all of which translates into a higher quality of life worldwide. And public policy has been moving in the right direction in most countries, albeit at a less than optimal pace.

Looking forward, there is some uncertainty regarding governmental support in some regions. Geopolitical shifts may stall some countries' progress on hydrogen allowing other countries to advance into global leadership positions (perhaps permanently). How do we keep the momentum going with hydrogen? I believe the answer lies in a quote I recently posted from the late Peter Drucker: "The best way to predict the future is to create it". So let's keep creating a better future together with hydrogen in 2025!

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  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 break-through liquid, slush, and gaseous hydrogen systems since the mid-1980s. Matt was also the Sector Manager for Energy & Materials in his last position at NASA where he worked for 31 years. He's been a co-founder in seven technology startups; and provided R&D and engineering support to many organizations. Matt has three patents and more than 50 publications including the Cryogenic Fluid Management series. He also teaches courses, workshops, and webinars on liquid hydrogen systems.