Densified Liquid Hydrogen and No-Loss (Zero Boil-off) Systems

Conference: Center for Hydrogen Safety (CHS) Asia-Pacific Conference, Nov 30 - Dec 2, 2021 AEST (Nov 29 - Dec 1 PST)

Abstract: Liquid hydrogen (LH2) can be thermodynamically conditioned to increase storage density compared to normal boiling point conditions in a process known as densification. A variety of methods to produce densified hydrogen have been successfully demonstrated using vacuum pumping or cryo-refrigeration. Additional system advantages beyond increased storage capacity include: increased cooling capacity for longer storage times or heat sink functions; greater vehicle payloads and/or range; higher mass flow rates; smaller hydrogen delivery components; and the potential for more efficient oxidizer-fuel ratios for some applications. No-loss LH2 systems have been demonstrated using cryo-refrigeration which enables zero boil-off storage and transfer operations. Gaseous hydrogen can also be liquified or re-liquefied in either continuous or batch processes. Additionally, high pressure and temperature LH2 can be thermodynamically conditioned to colder and lower pressure conditions without venting using cryo-refrigeration. The resulting system can operate for years without any boil-off losses. In the case of all these densified and zero boil-off LH2 systems, a key safety risk is the potential for subatmospheric conditions within the storage vessel and other fluid system components. The associated potential for air in-leakage and structural buckling failures can result in a catastrophic event. Proven mitigation methods are presented to manage this risk.

Slides: https://drive.google.com/file/d/1ASyZCrCRpu-SCY3ajDXZ3DNgWKvZ6xmE/view?usp=sharing

Video: 

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 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 cofounder in seven technology based start-ups; and provided R&D and engineering support to many industrial, government and research organizations. Matt has three patents and more than 50 publications including the Cryogenic Fluid Management report series. More about him can be found here.

Largest Liquid Hydrogen Dewar Tank (Ever)

NASA Kennedy Space Center Liquid Hydrogen Dewar Tank (credits: NASA/Kim Shiflett)

Isotherm Energy has been awarded a subcontract to provide support for development of the largest hydrogen dewar tank in history at the NASA Kennedy Space Center (KSC). As previously reported by NASA, the new dewar will hold well over one million gallons of liquid hydrogen and is 50% larger than the current record holder that supported space shuttle launches for 30 years (see above).

A primary focus of Isotherm Energy’s support is the analysis, design and integration of a new technology that eliminates hydrogen loss during storage. Shawn Quinn, assistant program manager of NASA KSC Ground Systems Development and Operations (GSDO), explained how the dewar and its unique capabilities will support the new Space Launch System [1], “…GSDO will fill the rocket's core stage and interim cryogenic upper stage with hundreds of thousands of gallons of liquid hydrogen. An important feature of the new zero boil-off technology is the potential to reduce long-term energy costs and liquid hydrogen commodity costs."

This key capability will build upon previous research demonstrations done by NASA to investigate an integrated system that can provide liquefaction, propellant densification, and zero boil-off. “The goal would be to integrate the unit's heat exchange system into the new tank, saving GSDO money by eliminating the loss of hydrogen”, according to Bill Notardonato, principal investigator for the 33,000 gallon demonstration unit (shown below) [2]. “By accomplishing zero boil-off of liquid hydrogen, we could save one dollar in hydrogen for every 20 cents spent on electricity to keep it cooled.”

(Photo credit: NASA/Cory Huston)

The successful design and operation of a liquid hydrogen storage system at this scale with zero boil-off, liquefaction and densification capabilities has far reaching implications even beyond the space program. For example, Isotherm Energy has developed a hydrogen energy storage architecture and associated system development software for renewable power sources (among other applications). The demonstrated ability to economically eliminate hydrogen losses for such a system – not to mention liquefy gaseous hydrogen and subcool the resulting liquid – would be a significant game changer.

[1] “Ultra-Cold Storage – Liquid Hydrogen May Be Fuel of the Future”, Amanda Griffin and Linda Herridge, NASA KSC, Dec 14, 2016.

[2] Ibid.

Matt Moran is the Managing Member at Moran Innovation, and previous Managing Partner at Isotherm Energy. He's been developing power and propulsion systems since 1982. Matt was also the Sector Manager for Energy & Materials in his last position at NASA where he worked for 31 years. He's been involved in seven technology based start-ups; and provided R&D and engineering support to many industrial, government and research organizations.  More about Matt here…