Salty Refrigeration is Friendly to the Environment

Widespread use of refrigerators is a hallmark of modern society, allowing people to store food and enjoy ice and cold beverages. However, a typical refrigerator uses gasses that are not always good for the environment. Now the Berkeley National Lab says they can change that using ioncaloric cooling, a new technique that uses salt as a refrigerant.

The new technique involves using ions to drive a solid-to-liquid phase change which is endothermic. Unlike some similar proposals, the resulting liquid material would be easy to pump through a heat exchanger. In simple terms, it is the same process as salting a road to change the melting point of ice. In this case, an iodine-sodium salt and an organic solvent combine. Passing current through the material moves ions which changes the material’s melting point. When it melts, it absorbs heat. When it resolidifies, it releases heat.

People often mention how different the world was without electricity. But another modern convenience we tend to take more for granted is refrigeration. Although the University of Glasgow demonstrated an artificial refrigerator as early as 1748, and there were some earlier designs, commercial refrigerators wouldn’t appear until 1834. Home refrigerators wouldn’t be practical until 1918. Before all this, there was a huge market for harvesting ice where it occurs naturally and transporting it to other places for underground storage and distribution. Early refrigerators used toxic gases. Your refrigerator could literally kill you until the development of a safer gas. But even modern gasses are not good for the environment.

The organic solvent used in the demonstration is actually carbon negative, another potential boon to the environment. With one volt of input, the phase change was 25C, which is, according to the post, better than other similar solid phase change systems.

The other related modern tech is air conditioning. It turns out rubber cools down when it changes shape, and you can use that to make a fridge, too.