Harmful chloroflurocarbons (CFCs) in refrigeration devices could be replaced with solid refrigerants that are more efficient and environmentally benign. Pedro Jorge von Ranke of the Universidade do Estado do Rio de Janeiro has shown that materials called spin-crossover systems have pressure-induced changes in entropy between low-spin and high-spin states that are large enough to use for a practical cooling cycle. These giant “barocaloric” effects are analogous to magnetocaloric effects, but use pressure instead of magnetic fields.