If we want to use hydrogen as fuel for cars or airplanes, or for chemical storage of excess renewable energy, it would be most efficient if it were liquid. However, this would require cooling it down to minus 253°C or 20°K, which is very energy-consuming when using a conventional cooling technology.
A team of scientists led by Graeme Blake , assistant professor of Inorganic Chemistry at the University of Groningen (the Netherlands), has been researching a more energy-efficient cooling method called magnetocaloric cooling. This method involves using materials that will heat up when they are exposed to a magnetic field. The heat is then transferred to a 'heat sink', which leaves the material - and its surroundings - colder once the magnetic field is removed. The method not only consumes less energy, but also eliminates the need for refrigerant gases, which have a strong greenhouse effect.
Blake used magnetocaloric cooling to reach 20°K, cold enough to liquify hydrogen. This has been done before, but only with materials containing rare-earth metals. The mining of these metals consumes a lot of energy and can lead to environmental problems. What's revolutionary about Blake's material is that it does not contain these metals: 'Our material, or a future variant of it, could probably reduce the cost and improve the environmental friendliness of this cooling technology.'
Reference: J.J.B. Levinsky, B. Beckmann, T. Gottschall, D. Koch, M. Ahmadi, O. Gutfleisch & G.R. Blake: Giant magnetocaloric effect in a rare-earth-free layered coordination polymer at liquid hydrogen temperatures , Nature Communications.
