‘Thermal inductor’ could convert boiling water to ice with no energy input
physicsworld.com
physicsworld.com
Note the article describes a way of moving the heat from one container to another - basically a heat pump just like any airconditioner produces 'cool'. (on one side of the system only, the side of course gets hotter.)
A refrigerator also requires energy.
Yes. To move the refrigerant around and compress it. The real work of a refrigerator is done by the Latent Heat of Evaporation and its corollary the latent Heat of Condensation.
In the change of state between liquid and gas, the latent heat is the same, but in one direction (gas to liquid) energy is released, and in the other direction (liquid to gas) energy is required.
Note that since the heating-cooling both produces heat and 'cold', a heat pump is the most economical way of drying clothes. The energy in the hot air evaporates the water in the clothing into water vapor which then passes over the cold plates and condenses that water vapor into water which is drained away. The heat energy produced by the condensation of the water vapor evaporates the refrigerant which is then compressed, releasing energy to reheat the circulating air so it can evaporate more water. Neat, hey?