Solid-state cooling: Is this the air conditioning of the future?

A new cooling technology, based on solid-state principles rather than traditional refrigerants, has been demonstrated in a supermarket refrigerator in Darmstadt, Germany. The device maintains a temperature of 6.2 degrees Celsius using magnetic fields to heat and cool a special metal repeatedly, with water circulation removing the heat. This system operates without harmful or flammable refrigerants and uses less electricity than a standard household refrigerator. Researchers believe this could one day replace conventional air conditioning systems in homes, hospitals, and schools, though its widespread adoption remains uncertain. The technology relies on the magnetocaloric effect, a physical phenomenon known since the early 20th century. When certain materials are exposed to a magnetic field, their atomic magnetic moments align, reducing entropy and causing them to warm up. Removing the field allows the material to cool down. While the principle was understood long ago, practical applications have only recently become feasible due to advances in material science. In the 2000s, scientists at the Technical University of Darmstadt identified a promising alloy composed of lanthanum (La), iron (Fe), and silicon (Si), known as LaFeSi, as a potential candidate for such systems. This research caught the attention of physicist Maximilian Fries, who was pursuing his doctorate at the time. Fries had two passions: magnets, which he found fascinating despite their quantum mechanical complexity, and efficiency, believing society must use energy more wisely. Driven by these convictions, Fries began researching LaFeSi. One challenge was corrosion in water environments. To address this, he developed a protective coating. His work led to the founding of the startup Magnotherm in 2017, alongside colleagues from the university. The development of this coating took five years. It involves depositing copper onto a porous LaFeSi cube in a specialized bath, with exact temperature ranges and chemical compositions forming the company’s proprietary knowledge. Fries' company, Magnotherm, operates from a space resembling a typical startup office, complete with ping pong tables, chessboards, open-plan offices, workshops equipped with 3D printers and precision tools, and even a chemistry lab. The environment fosters collaboration and innovation. The company's cooling machines employ two separate water circuits. As a magnet passes over the porous LaFeSi cube, the material heats up, and a circuit removes the waste heat. Once the magnet moves away, the material cools, and another circuit captures the cold to provide cooling. This process occurs two to three times per second. The integration of materials, fluid dynamics, and control systems is central to Magnotherm’s approach. Development of climate control solutions at Magnotherm in Darmstadt, recorded in 2022. The company continues refining its technology, aiming to bring this innovative cooling method into broader application. However, whether it can compete with established technologies remains to be seen.