Cryogenic Solid-State Thermal Energy Storage

Navy SBIR 23.1 - Topic N231-068
ONR - Office of Naval Research
Pre-release 1/11/23   Opens to accept proposals 2/08/23   Closes 3/08/23 12:00pm ET    [ View Q&A ]

N231-068 TITLE: Cryogenic Solid-State Thermal Energy Storage

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): General Warfighting Requirements (GWR)

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals (FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with the Announcement. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws.

OBJECTIVE: Develop a cryogenic temperature retaining material that can maintain its cryogenic temperature for a time period of 2-4 hours without substantially increasing the final system weight.

DESCRIPTION: The U.S. Navy has been investigating the use of high-temperature superconductors for nearly four decades. A key aspect of the superconducting system is the need to keep the conductor at a cryogenic temperature. Typically a cryocooler is a major component of the overall superconducting system; however, certain applications may limit the use of an active cryocooler. There may also be times when a cryocooler may not have power, such as when the ship pulls into port and generators are powered down when switching to shore power. This SBIR topic seeks a material that can retain the cryogenic temperature in the superconducting system for a given time to either; operate without active cooling once the operational temperature is achieved; or if there is a loss of power to the cryocooler and the system still needs to remain operational for a given amount of time.

One solution to this problem is to increase the overall thermal mass by adding large amounts of conventional solid materials, such as copper. While doing so guarantees the system will take longer to warm up, the entire system quickly becomes too heavy to effectively deploy. Additionally, materials exist which can maintain a particular temperature for a short amount of time by utilizing latent heat during phase change; however, they are not tuned for such extreme temperatures and typically transition at least one phase of matter. Such technologies have given rise to freezer packs used to keep food frozen while not in a freezer.

Previous research attempts utilized a block of solid nitrogen capitalizing on the latent heat of vaporization. The expansion and sealing at gas phase were problematic. The large expansion ratio between nitrogen gas and solid resulted in a nitrogen supply of several hundred times the volume of the desired solid. Given the asphyxiation hazard associated with gaseous nitrogen in an enclosed environment, liquid and solid nitrogen are not currently used on naval platforms as cryogens, and such a solution is not desirable for this topic.

Alternatively, water has also been discussed as potential thermal phase change material. Unlike nitrogen, it does not expand as it heats up, but instead expands upon freezing by approximately 9%. Given the vacuum sealed nature of superconducting system, this expansion, coupled with the non-compressible nature of water, can potentially result in system damage if the expansion is not properly accounted for.

Certain materials undergo solid-solid phase change, and others have such low expansion ratios upon phase change that they can be encapsulated without concern of system damage. This makes such technologies a more attractive alternate for naval use.

The topic seeks to develop a fully encapsulated material with negligible expansion, or a solid material that can retain the operational temperature of 30 K on the order of 2-4 hours, without increasing the total system weight by more than 10%; (i.e., if the superconducting system mass is 5000 kg, the total mass of the thermal energy system (including auxiliary hardware) must remain below 500 kg). The volume of the system must also be balanced with the weight restrictions. The solution must retain 30 K with a 100 W heat load for at least 2 hrs. Longer timelines or higher heat loads are more desirable. The solution must be stable not only at 30 K but also at 313.7 K (elevated room temperature), and it must withstand the thermal shock of cooling down from 313.7 K to 30 K. The solution must remain viable for over 10,000 cool-down/warm-up duty cycles. Lastly, the solution must be affordable to the Navy for implementation into a superconducting system and should be as low-cost as possible.

PHASE I: Conduct a feasibility analysis of the technological ability to meet desired performance specifications. Demonstrate the design and manufacturing concepts through modeling, analysis, and benchtop testing. Identification of size, weight, nominal performance, performance at cryogenic temperatures, and warm-up times shall be documented. Upon a feasible solution the awardee, shall perform a cost estimate, for both prototype development and full-scale production. The Phase I Option, if exercised, includes a detailed design and specifications to build a prototype during a Phase II effort.

PHASE II: Develop, design, and fabricate a functional prototype of a cryogenic phase change material for temperature retention. Commence with characterization of key performance metrics at the awardee’s facility or other suitable test center identified by the offeror. Provide a warm-up time of the solution under various heat loads that may be experienced by a cryogenic system. Deliver the Phase II prototype to the Navy for further testing. Submit all maintenance and integration relevant designs and drawings of tested solution in addition to any updated designs, design changes, and related drawings that result from lessons learned discovered during prototyping. For material based solutions full Safety Data Sheets shall be required.

PHASE III DUAL USE APPLICATIONS: If successful demonstration of the technology is achieved, the transition of the development will lead to the sustainability of a superconducting system if there is a failure of the cryogenic refrigerator, or if there is no cryogenic refrigeration system available for a short time. This will enhance Fleet readiness when deploying superconducting systems in the Fleet. There are several superconducting systems that are currently being transitioned to the Fleet and this technology may be implemented in future upgrades to those systems, or in superconducting systems currently in development.

Additional use of this technology in the commercial sector may be implemented in superconducting systems being developed for the wind power generation market, resilient power grid, superconducting propulsion for aviation, and/or existing medical devices such as MRIs.


1.       Lee, Jisung; Jeong, Sangkwon; Hee Han, Young and Park, Byung Jun. "Concept of cold energy storage for superconducting flywheel energy storage system." IEEE Transactions on applied superconductivity 21, no. 3 (2010): 2221-2224.

2.       Bugby, D.; Marland, B. and Stouffer, C. "Development and testing of a 35K cryogenic Thermal Storage Unit." In 41st Aerospace Sciences Meeting and Exhibit, p. 343. 2003.

3.       Suttell, N.; Zhang, Z.; Kweon, J.; Nes, T.; Kim, C.H.; Pamidi, S. and Ordonez, J.C. "Investigation of solid nitrogen for cryogenic thermal storage in superconducting cable terminations for enhanced resiliency." In IOP Conference Series: Materials Science and Engineering, vol. 278, no. 1, p. 012019. IOP Publishing, 2017.

4.       Shamberger, Patrick. "Cooling Capacity Figure of Merit for Phase Change Materials." ASME Journal of Heat Transfer, vol. 138, February 2016. DOI: 10.1115/1.4031252

5.       Jankowski, N.R. and McCluskey, F.P. "A review of phase change materials for vehicle component thermal buffering." Applied Energy 113 (2014) 1525–1561.


KEYWORDS: Cryogenic Temperature Retention; Phase Change Material; Superconducting Systems; Energy Storage

TPOC-1: Harold Coombe

Email: [email protected]


TPOC-2: Peter Ferrara 

Email: [email protected]


The Navy Topic above is an "unofficial" copy from the Navy Topics in the DoD 23.1 SBIR BAA. Please see the official DoD Topic website at for any updates.

The DoD issued its Navy 23.1 SBIR Topics pre-release on January 11, 2023 which opens to receive proposals on February 8, 2023, and closes March 8, 2023 (12:00pm ET).

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Topic Q & A

2/2/23  Q. Are there any materials that should not be proposed?
   A. Thermal energy storage materials that are considered to be fuels, or are flammable, will not be considered due to the difficulty in handling and storing such materials.
1/25/23  Q. Will the 100 W heat load be transferred through a single plane or uniformly through all planes into the thermal storage device?
   A. If the “plane” being referenced is the outside of the bulk material, then the heat load can be viewed as 100 W distributed over each surface. If you are referring to the internal crystal structure the answer varies based on the exact solution.

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