If you ask a group of people what their favorite household appliance is, many will say the dishwasher or washing machine. Thanks to technology applied to the home, modern humans save dozens of hours of manual labor at home. However, a rather silent hero is the one that allows us to shop once a week. Our refrigerator is, if we think about it, the most essential appliance in the modern home: it runs 24 hours a day, seven days a week, and keeps our food fresh for days or weeks.
However, behind this community lies an environmental problem; despite being a great help in our daily lives, these appliances are also a climate time bomb. Their refrigerant gases are quite problematic: HFCs, while not damaging the ozone layer, contribute slightly to global warming. Their global warming potential (GWP) is extremely high, thousands of times greater than that of carbon dioxide. However, researchers at Lawrence Berkeley National Laboratory and the University of California have presented an alternative technology: “ionocaloric cooling.”
How does a refrigerator work?
This large metal cabinet in our kitchen works thanks to vapor compression. It is a closed pipe circuit, like an organic circulatory system. In it, a refrigerant fluid—traditionally a gas—does all the work. This fluid absorbs heat from inside as it evaporates, and then releases that heat to the outside as it condenses. The key component driving this cycle is the compressor, the loudest and bulkiest part of the refrigerator.
This system is efficient, but international bureaucratic pressure to change it is enormous. Repression is Kilani’s amendment, a 2016 international agreement to gradually reduce the production and consumption of hydrofluorocarbons (HFCs), which are the largest greenhouse gases. This is why companies are looking for viable alternatives that do not require such polluting compounds.
Scientists have been inspired by the salt that is spread on icy roads. This salt, which consists of ions, has a single purpose: to lower the melting point of ice, causing it to melt. As it melts, the ice absorbs heat from its surroundings. This is precisely the ionocaloric effect. In the laboratory, scientists have managed to build a system using harmless salt (sodium iodide) and a common liquid solvent (ethylene carbonate).
The results of the initial experiment were incredible; they achieved a temperature change of 45°F using less than a single volt, which surpasses almost all other caloric technologies. It seems that refrigerators in the coming years will come with this technology, as it has nothing but advantages: they will be built with neutral refrigerants and compounds with zero greenhouse gases, they will be highly energy efficient, and they will cost less to manufacture.
History of the domestic refrigerator
The evolution of technology is overwhelming; just a century ago, electric refrigerators did not even exist. People relied on the icebox, which was a simple insulated cabinet. If you wanted to keep your food fresh, you had to wait for an ice seller to come by and buy a block of natural ice. Depending on the temperature, this block of ice could last you a week in summer or a couple of weeks in winter.
The first electric refrigerator arrived in homes in the early 20th century, but it used toxic and dangerous gases (such as ammonia). These were replaced by Freon in the 1930s… which seemed safe, but turned out to be a danger to the ozone layer. It was replaced and then HFCs were used, which have turned out to be just as problematic.
For now, the new ionocaloric technology is in laboratories. They are still studying the creation of functional prototypes that demonstrate that the system can be scaled up to large refrigerators and air conditioning systems. However, researchers are very optimistic about its low (or zero) PCG, high efficiency, and low production cost. It seems that in a few years our refrigerators will not have polluting gases or make strange motor noises. They will be quiet, efficient, and much more environmentally friendly. The only question is… how will we know when it breaks down if it never makes any noise? Well, that’s aproblem for future generations.
