Crystals, nozzles and magnets – how can cooling be made extra environmentally pleasant?

In a world plagued by climate change, refrigeration is anything but a luxury. It saves lives, keeps food fresh and provides convenience at home or in the office. Ten new air conditioners will be sold every second by 2050 according to the International Energy Agency.

But all these machines, running for hours, consume tons of electricity. In addition, these devices usually contain refrigerant gases, which are many times more harmful than CO2 in terms of global warming potential. the gases gradually phase outeven after throwing away old air conditioners or refrigerators.

Ironically, cooling to survive the climate crisis could actually make the problem much worse. Because of this, there are numerous startups in Europe and around the world exploring new technologies that could make refrigeration significantly more efficient than it is today. And they have unusual ideas.

No liquids, no leaks

In a Cambridge lab, Xavier Moya, co-founder of Barocal, has a prototype of a machine that applies pressure to plastic crystals – lattices of organic molecules. This creates a strong cooling effect that lowers temperatures by 20 °C or 30 °C, for example.

“We don’t use gas, so it won’t leak,” says Moya. Barocal currently employs six people and has raised £1.5m in funding.

The technology is based on the fact that the molecules in the solid refrigerant rotate naturally, but come to a standstill under pressure. “When you remove the pressure, the molecules want to spin again and have to absorb energy – so they cool down,” says Moya.

He adds that the process is somewhat similar to what happens in liquid crystal displays. Such displays contain molecules that change their orientation when an electric field is appliedso you can see numbers on your calculator screen, for example.

Barocal’s solid refrigerant could be used in air conditioners or refrigerators on both a residential and commercial scale, says Moya. He claims that the system will be extremely efficient. In cooling and heating systems, one kilowatt hour (kWh) of electricity is often used to generate several kilowatt hours of thermal energy – the so-called coefficient of performance (COP). With modern heat pumps, for example, you can achieve a COP of 3 at home, which means that for every kWh of electricity consumed, 3 kWh of heat are produced.

“We’re expecting efficiencies that are double or greater,” says Moya, adding that his company is years away from releasing a commercial product.

Another startup that wants to do without refrigerants is Dynamic Air Cooling in Poland. The company employs 13 people and has raised EUR 3.5 million in funding, of which EUR 2.3 million is in the form of grants.

“Mini Tornado”

Co-founder and CEO Pavel Panasyuk says his team came up with the idea more or less by accident while experimenting with the same technology used in jet engines.

“We created a process that is very similar to a mini tornado,” he says. It’s the twisting and twisting of the air that creates a cooling effect, as it converts the air’s thermal energy into kinetic energy instead, he explains. The system can reliably lower temperatures by around 45°C, and in experiments it has worked with starting points between 0°C and around 35°C, Panasyuk adds.

A thorny issue is that there is currently no definitive method for determining a specific exit temperature. So the team is working on a control unit to make this possible. “There is a solution,” Panasyuk suggests, adding that the system should achieve a COP of around 4.

Once all the technical challenges are overcome, he hopes Dynamic Air Cooling will have a commercial product ready in a year. The Company focuses on industrial refrigeration for food storage and transportation.

Magnotherm in Germany is also striving to make refrigerators more environmentally friendly, but with a completely different technology. Timur Sirman, co-founder and CEO, explains that his startup’s device is based on rotating magnets. Imagine two of them, like burger buns, above and below the “burger”, in this case a special iron alloy full of pores through which water can be pumped. The magnetic field generated by the rotating magnets cools the metal alloy and thus the water flowing over it.

The pursuit of efficiency

The company, which employs 32 people and has raised €6.3 million so far, already has a small commercial product – a refrigerator, which it rents out to event organizers. The fridge, named Polaris, holds between 100 and 200 drinks, according to Sirman, but only has a COP of 1, which isn’t very efficient. However, this can be solved by building a larger fridge, he adds.

“The cooling capacity scales linearly with the amount of material you put in,” says Sirman. With the same engines and water pump, but more porous iron alloy, the team hopes to achieve more cooling and a COP of up to 5 in 2024.

In principle, the same technology could also be used in an air conditioning system, but that is not currently the focus of Magnotherm. The hope is that their system will find application in commercial refrigerators, in a modular unit that can be removed and installed in a new refrigerator whenever the customer, say a supermarket, decides to upgrade their hardware.

It’s “fantastic” to see so much innovation in cooling, says Nicole Miranda, a researcher in the Future of Cooling Program at the Oxford Martin School, part of the University of Oxford. She emphasizes that passive cooling techniques – from textiles that keep our bodies cool to more shading in inner cities – will be just as important in the years to come as technologies that require electricity to function.

But demand for air conditioners and refrigerators will be huge around the world, she adds. It is therefore important to develop sustainable systems now that do not consume an excessive amount of energy or are made from materials that have a high CO2 footprint.

Also think of the many houses that existed across Europe Never designed to keep out excessive summer heat. And it’s not yet clear whether these countries’ power systems will be able to cope with the booming demand for cooling technology in the coming years.

“It’s an easy solution to just go to a store and get an air conditioner,” says Miranda. “It’s a big risk to the power grids in those places.”

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