New cooling technology aims to condition air without polluting gases

 An innovation—a soft, white, waxy paste with promising properties that changes temperature by more than 50 degrees under pressure—paves the way for a revolutionary generation of air conditioners free of greenhouse gases.

Unlike the gases used in current devices, these "solid refrigerants" do not leak. Xavier Moya, a professor of materials physics at the University of Cambridge, says these materials are "more energy efficient."

There are approximately two billion air conditioners in use worldwide, and their number is increasing as the planet warms. Between leaks and energy consumption, their associated emissions are also increasing every year, according to the International Energy Agency.

Xavier Moya has been studying the properties of these "plastic crystals" in his laboratory at the prestigious British university for 15 years.

On his workbench is a large red and gray machine topped with a cylinder, which tests the temperature of the material based on pressure.

This step aims to identify the best refrigerants among this class of materials already used in chemistry and relatively easy to obtain (the exact molecular composition remains a secret).

This phenomenon is not visible to the naked eye, but the crystals are composed of molecules capable of rotating. When pressed, their motion is halted and their energy is dissipated as heat. Releasing them, on the other hand, lowers the ambient temperature, a phenomenon known as the "barocaloric effect."

Clive Elwell, a professor of building physics at UCL London, told AFP that "the demand for air conditioning will increase dramatically worldwide by 2050." He believes that barocaloric solids have the potential to be as efficient as, if not more efficient than, gas.

He added, "Whatever new technology is launched, it will have to meet basic requirements," such as the size of the device or the noise it produces, if it hopes to find its way into homes and cars.

In addition to his research at Cambridge, Xavier Moya founded a startup in 2019 called Barocal to put his research group's discoveries to practical use. The company has nine people and its own laboratory, currently a modest warehouse in a parking lot.

But the startup is attracting followers. In recent years, it has raised around €4 million, primarily from the European Innovation Council, a European Union program in which the UK participates, and Breakthrough Energy, an organization founded by American billionaire Bill Gates.

The company plans to increase its workforce to 25 or 30 people this year.

Inside the warehouse, the prototype air conditioner is about the size of a large suitcase. Far from being small, it makes a loud humming noise as the hydraulic circuit increases and decreases the pressure in the four pellet-filled cylinders.

But the device works. A small refrigerator is attached to the system, and the soft drink cans inside are kept perfectly cold.

Barocal materials engineer Mohsen Al-Abadi acknowledges that this prototype "hasn't been truly optimized yet, neither in terms of mass, size, nor even sound."

However, the new systems the company is developing will be similar in size to gas-powered systems and will be just as quiet.

While the company is currently focusing on cooling, this technology could also be used to generate heat.

Several teams around the world are studying these materials, but the Cambridge team is leading the way, according to Breakthrough Energy, which notes that these devices "have the potential to reduce emissions by up to 75%" compared to conventional systems.

Barocal hopes to launch "the first product on the market within three years," according to sales manager Florian Schabos. Initially, this will be "cooling units for large shopping malls, warehouses, schools," and even "data centers."

He believes that convincing companies of the technology will be easier initially if it is more expensive to purchase but contributes to lower energy bills. Barocal ultimately aims to achieve prices equivalent to traditional individual targeting systems.