CLIMATE: Could this strange dough revolutionize air conditioning?

It is a soft paste like wax, white and grainy, with promising properties: its temperature varies by more than 50 degrees under pressure, opening the way to a revolutionary generation of air conditioners without greenhouse gases.

Unlike the gases used in current devices, these “solid refrigerants” do not flee. They “are also potentially more energy efficient”, summarizes Xavier Moya, professor of materials physics at the British University of Cambridge.

About 2 billion air conditioners are in service worldwide and their number climbs as the planet heats up. Between leaks and energy consumption, associated emissions are also increasing each year, according to the International Energy Agency (AIE).

Xavier Moya has been studying the properties of these “plastic crystals” in his laboratory in the prestigious British university for 15 years. On its work plan sits an imposing red and gray machine, surmounted by a cylinder, which tests the temperature of the material as a function of the pressure.

Objective: Identify the best refrigerants among this class of materials already used by the chemical industry and quite easy to obtain (the exact composition of the retained molecules remains secret).

The phenomenon is invisible to the naked eye, but these crystals are composed of molecules capable of turning on themselves. When they press them, their movement blocks and they dissipate their energy in the form of heat. Release them, conversely, lower the surrounding temperature. It is “the barocaloric effect”.

“The demand for air conditioning will increase considerably worldwide by 2050,” said AFP Cliff Elwell, a building physics professor at UCL University in London, for whom Barocaloric solids have the potential to be as effective, or even more, than gas.

“But whatever the new technology that will eventually be launched, it will always have to meet the basic requirements”, especially on the size of the device or the noise it produces, to hope to make your way in homes and cars, “he warns.

In addition to his research in Cambridge, Xavier Moya created in 2019 a Startup, Barocal, to concretely apply the discoveries of his research group. It employs nine people and has its own laboratory -for the moment a modest container in a parking lot.

But the “young shoot” has been emulated: in recent years it has raised around 4 million euros in recent years, notably from the European Innovation Council, an EU program associating the United Kingdom, and Breakthrough Energy, an organization created by the American billionaire Bill Gates. She plans to bring her workforce to 25 or 30 people this year.

Inside the container, the first air conditioner prototype is the size of a large suitcase: far from being a miniaturization miracle, it also buzzes fairly noisily when a hydraulic circuit increases or decreases the pressure in the four cylinders filled with crystals.

But it works. A small refrigerator is attached to the system and the soda cans that are there are perfectly fresh. This first prototype “has not yet been truly optimized, neither on his mass, nor on his volume, nor even on sound”, recognizes the materials materials at Barocal Mohsen Elabbadi.

But the new systems that the company is perfecting will be comparable in size and as silent as those operating on gas, he promises.

If the company is currently focusing on the cold, technology can also be used to produce hot. Several teams study these materials around the world, but that of Cambridge is a pioneer in this area, according to Breakthrough Energy, which estimates that these devices “have the potential to reduce emissions up to 75%” compared to traditional systems.

Barocal hopes to launch “a first product on the market in three years”, according to Florian Schabus, the commercial director. It will first be “cooling units for large shopping centers, warehouses, schools” or “data centers”.