Pascal claims 20% efficiency gain for fridges, still at lab stage

When the measurements came back, Adam Slavney and Jinyoung Seo had no explanation. Their team at Harvard University was testing a new class of materials meant to make refrigerators, air conditioners and heat pumps more efficient, and two readings that should have matched did not. “Why are these things different? What did we change?” Slavney recalls asking. The answer was a gas swap made during high-pressure measurements: the instrument needed a gas, and the team changed which one they used. That puzzle, which took one or two years to prove, is now the basis of Pascal, the startup where Slavney is chief executive and Seo chief technology officer.

The search for better refrigerants is almost as old as the appliances themselves. Freon, an earlier refrigerant, ate a hole in the ozone layer, and newer ones such as R-134a remain extremely potent greenhouse gases. Slavney calls it “a never-ending treadmill.” Solid-state refrigerants offer a way off that treadmill: because the working material stays solid, it cannot escape into the atmosphere, and it gives off heat when squeezed and absorbs it when pressure is released.

Pascal does not squeeze a solid block. It feeds carbon dioxide (CO2), a gas, into a cartridge filled with a sponge-like material that the company keeps proprietary. As the gas works into the pores, its molecules bounce off the walls, transfer energy to the material and warm it, and a heat exchanger releases part of that heat. Run in reverse, the material draws energy from the heat exchanger and hands it to the gas. A Pascal refrigerator runs two cartridges at once: one pulls heat from inside the fridge, the other sends it to the outside air, and the flow reverses when the cartridges become too hot and too cold.

Durability is the figure the team cites most. The material has been cycled up to 300,000 times, which Slavney equates to roughly a year of operation. The company says the whole system moves heat more effectively than other solid-state designs, so it does not need the high pressures those designs may demand. The 20% efficiency gain is Pascal’s own projection for a refrigerator or heat pump using its material, and the company has not yet delivered a working prototype.

The first concrete customer is a multinational beverage company, which signed a pilot contract earlier than Pascal expected. A first prototype is due early next year and a batch of more polished refrigerators in 2028. Slavney’s bet now rests on cost: because the system uses conventional components, he believes it can be made cheap, and that is what would let it spread beyond pilots. Whether the 20% holds in a product that people can buy is what those dates will test.