Cooling the planet: US researchers develop new climate-friendly method of cooling

The planet is getting hotter and our fridges and air conditioning units are turning up the heat.

Direct and indirect greenhouse gas emissions from cooling equipment – to keep humans safe, food and vaccinations stable, energy and data supply running – have doubled to nearly 1 gigaton (1 gigaton = 1,000,000,000 tonnes) between 1990 and 2021, the International Energy Agency says in its space cooling report.

This is set to increase further as global warming, urbanization and a rising middle class in developing countries fuel demand for ACs and fridges.

But we can’t simply just turn them off. Around 30% of the world’s population is currently exposed to life-threatening temperatures for at least 20 days a year and heat waves already lead to 12,000 deaths annually across the world, according to the United Nations-led Cool Coalition.

“Lack of cooling kills, but so does providing inefficient, polluting cooling,” the Coalition warns.

Researchers at the US Department of Energy’s Berkeley Lab have developed a new method of cooling and heating which they say is more climate friendly.

The technique, which they have named “ionocaloric cooling”, is described in a paper published in December in the journal Science.

“The landscape of refrigerants is an unsolved problem: No one has successfully developed an alternative solution that makes stuff cold, works efficiently, is safe, and doesn’t hurt the environment,” said Drew Lilley, a graduate research assistant at Berkeley Lab and PhD candidate at UC Berkeley who led the study. “We think the ionocaloric cycle has the potential to meet all those goals if realized appropriately.”

Here’s how it works, according to the scientists: “Ionocaloric cooling takes advantage of how energy, or heat, is stored or released when a material changes phase – such as changing from solid ice to liquid water. Melting a material absorbs heat from the surroundings, while solidifying it releases heat.”

Heating and cooling accounts for more than half the energy used in homes. The Berkeley Lab researchers say the new technology could replace the currently used “vapour compression” method which is harmful to the environment.

It could also help countries to meet climate change goals, such as those in the Kigali Amendment. This stipulates that the signatories will reduce production and consumption of the HFC greenhouse gases found in refrigerators and air conditioning units by 80% over the next 25 years.

The ionocaloric innovation is only the latest technology to help cool the planet.

In other developments, Geneva in Switzerland is using deep lake water to cool buildings and replace air conditioning, and cutting electricity consumption by 80%. In the winter it works the other way around, by adding heat pumps to the closed loop system, it keeps buildings warm.

Singapore is using a similar system that has managed to cut energy demand for cooling by an estimated 40%, reports Spectra. That’s the equivalent energy usage of 24,000 apartments in the city-state, which is one of the hottest and most humid places in the world.

US company SkyCool is installing panels – not unlike solar panels – coated with a film technology that reflects radiation from the sun on buildings and bus shelters to keep people cooler without using electricity.

Meanwhile, the Berkeley Lab researchers are hopeful that ionocaloric cooling (and heating) will tick all the necessary boxes to make a difference in the world.

"There are three things we're trying to balance: the GWP (global warming potential) of the refrigerant, energy efficiency, and the cost of the equipment itself,” the co-author of the study, Ravi Prasher, said. "From the first try, our data looks very promising on all three of these aspects."