A first-of-its-kind demonstration unit is showcasing hydrogen liquefaction using magnetocaloric cooling, a process that demands much lower energy consumption than conventional methods used in industry. A joint venture between Magnotherm Solutions GmbH (Darmstadt, Germany; www.magnotherm.com) and Helmholtz-Zentrum Dresden-Rossendorf (HZDR; Dresden, Germany; www.hzdr.de), as part of the E.U.-funded HyLICAL project, has begun operations at the new facility on HZDR’s campus, showcasing a technology that has the potential to cool hydrogen to temperatures as low as –253ºC using powerful magnetic fields.
“Magnetocaloric cooling offers a completely different thermodynamic approach compared to current technologies. It employs specialized materials that change temperature in response to a magnetic field. After the material is magnetized, a transfer fluid is used to transport heat and establish a cyclic cooling process,” explains Magnotherm engineer Thomas Platte. Compared to hydrogen liquefaction using compressors or expansion turbines, which are hindered by pressure losses, refrigerant performance and mechanical complexity, the magnetocaloric technology can “directly convert magnetic work into cooling energy without generating excess work, making gas-liquefaction plants more energy-efficient using smaller footprints,” according to Platte. Also, in contrast to current techniques, the only heat-transfer fluid required for the magnetocaloric cooling system is helium, which is used to liquefy the hydrogen in an external heat exchanger. This makes this technology much safer than the direct use of hydrogen under high pressures.
Economies of scale are key in the commercial applicability of the new technology. “A major advantage of the technology is that it is less dependent on fixed scaling. Systems with lower capacity can operate efficiently, while investments remain within reasonable limits. Due to its compact design, scaling output is possible by multiplying the number of systems, which is ideal for an organic, demand-driven ramp up of liquefaction capacities with little upfront investment,” notes Platte. The small footprint of the system also provides benefits for integration with other processes, such as steelmaking, since the cold liquid hydrogen itself can provide cooling energy. The team is currently working to increase the demonstration unit’s output to 100 kg/d of liquid hydrogen to highlight its scalability.