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P3-390Introduction of JST MIRAI Project "Development of Advanced Hydrogen Liquefaction System by Using Magnetic Refrigeration Technology"Key Words: Magnetic refrigeration, Hydrogen liquefaction Hydrogenisconsideredastheultimateenergycarrierforreducingcarbondioxideemissions.Sinceliquidhydrogenhasavolumeof1/800thatofhydrogengas,ithasfeaturessuchasmasstransportation,masssupply,massstorage,andspacesaving.However,theproblemwithliquidhydrogenisthatthecurrentliquefactioncapacityofgasrefrigeratorsislow,sotheintroductionofinnovativetechnologiessuchasmagneticrefrigerationtechnologyisrequiredtoreducethecostofliquefaction.Ourprojectwasselectedasa10-yearinitiativeundertheJSTMiraiProgramin2018.⚫We succeeded in hydrogen liquefaction by newly developed AMR.⚫The gigantic magnetic entropy change of 0.35 J/cm3K in HoB2for a field change of 5T at 15 K is the highest value reported so far. HoB2is a highly suitable material for hydrogen liquefaction. ⚫We have demonstrated a series of materials with a giant magnetocaloric effect (MCE) in Er(Ho)Co2-based compounds, suitable for operation in the full temperature range required for hydrogen liquefaction (20 –77 K).ConclusionOverview of our projectRepresentative Research AchievementsTo achieve actual user adoption and utilization, research and development must address the following points. Therefore, securing additional research funding is essential to enable true societal implementation.⚫Ensure reliable, long-term operation.⚫Reduce initial and ongoing costs.⚫Aim for large-scale liquefied hydrogen storage.⚫Establish regulatory frameworks.Future PlanIntroductionMagneticrefrigerationusingthemagnetocaloriceffecthaspotentialtorealizeliquefactionefficiencyhigherthan50%,andalsotobeenvironmentallyfriendlyandcosteffective.Ahybridrefrigerationcycleconsistingofprecoolingcycleandmagneticactiveregeneratorcyclehasbeenproposedandestimatedtoachievealiquefactioncapacityof100kg/daywithFOM=0.5.Ournewprojectiscommittedtodeveloping(1)suchahighlyefficienthydrogenliquefierandalso,(2)compactandenergysavingre-condensationrefrigeratortorealizezeroboil-offintheliquidhydrogenstorage.Thisfiscalyearmarksthefirstofthethree-yearthirdstage,duringwhichweplantodevelopaprototypemachinecapableofachievingproof-of-concept(POC)bytheendoffiscalyear2027,withthegoalofsocietalimplementation.Theme underDiscussionCenter for Advanced Battery Collaboration (ABC),, GREEN Hideaki KitazawaE-mail：： KITAZAWA.Hideaki@nims.go.jpTwo Active Magnetic Refrigeration (AMR) bets are placed on the central axis of the magnetic field, and their respective cooling parts are generated at the center by vertical movement. The liquefaction is monitored by thermometers placed in the hydrogen space. It is seen that the output voltage of silicon diode level sensors rises in sequence from the bottom in response to the increase of liquid level. (K. Kamiya et al. Appl. Phys. Express, 2022)Magnetic refrigeration generates heat (cooling) by magnetizing (demagnetizing) the spins of magnetic atoms in a magnetic substance with a magnetic field. The project consists of four universities, two national research institutes, and ten companies, with NIMS primarily managing the organization.An all-Japanese organization is taking up the challenge of this theme.Prof. Nishimiyaof NIMS is a program manager as our representative.Hydrogen liquefaction efficiency, cost, and demandYearHydrogen supply costHydrogen liquefaction cost100JPY/Nm310JPY/Nm330JPY/Nm37JPY/Nm333JPY/Nm3Hydrogen Demand20JPY/Nm30.3 Mtons10 million tons200 tonsAiming for over 15% refrigeration efficiency at 20K and over 20W.Refrigeration efficiency% CarnotRefrigeration capacity at 20KEstimated model: Liquid hydrogen storage container (10m3), Evaporation rate 1.5%/dayExisting refrigeration systemWe have established two Proofs of Concept (POCs). The first POC (POC1) aims to realize a magnetic refrigerator capable of achieving over 50% refrigeration efficiency and producing over 100 kg/day of liquefied hydrogen. The second POC (POC2) aims to realize a magnetic refrigeration recondensercapable of achieving zero boil-off.POC1POC2Principle of Magnetic RefrigerationProject Organizational StructureTwo Proofs of Concept (POCs)0.350.300.250.200.150.100.050.00403530252015105|S| (J/cm3・K)T(K)5 T4T3T2T1TEr(Co,Ni,Al,Fe)2HoB2We have developed two typical examples of magnetic refrigeration materials exhibiting distinct magnetic entropy changes. HoB₂ demonstrates the highest magnetic entropy change at the hydrogen liquefaction temperature (P. B. Castro et al.,NPG Asia Materials, 2020). Er(Co,Ni,Al,Fe)₂are magnetic refrigeration materials suitable for cooling via the AMR method over the temperature range from 20 K to 77 K (X. Tang et al., Nature Comm., 2022).