UK lab promises air-con revolution without polluting gases
By AFP
May 12, 2025
A 'solid refrigerant' used by Barocal at their headquarters in Cambridge - Copyright AFP VALENTIN FLAURAUD
Olivier Devos
The soft, waxy “solid refrigerant” being investigated in a UK laboratory may not look very exciting, but its unusual properties promise an air-conditioning revolution that could eliminate the need for greenhouse gases.
The substance’s temperature can vary by more than 50 degrees Celsius (90 degrees Fahrenheit) under pressure, and unlike the gases currently used in appliances solid refrigerants, it does not leak.
“They don’t contribute to global warming, but also they are potentially more energy efficient,” Xavier Moya, a professor of materials physics at the University of Cambridge, told AFP.
Approximately two billion air-conditioner units are in use worldwide, and their number is increasing as the planet warms.
Between leaks and energy consumption, the emissions associated with them are also increasing each year, according to the International Energy Agency (IEA).
Moya has been studying the properties of these plastic crystals in his laboratory at the prestigious UK university for 15 years.
On his work surface, a large red and grey machine, topped with a cylinder, tests how the temperature of a substance changes under pressure.
The aim is to identify the best refrigerants among this class of materials, which are already used by the chemical industry and are relatively easy to obtain, even if the exact composition of the crystals eventually selected remains secret.
The phenomenon is invisible to the naked eye, but these crystals are composed of molecules that spin on their own axis.
When the substance is squeezed, that movement stops and the energy is dissipated in the form of heat.
When released, the substance cools its surroundings in what is known as the “barocaloric effect”.
– Chilled cans –
“We’re expecting demand for air conditioning to increase hugely, globally, between now and 2050,” Cliff Elwell, a professor of building physics at University College London, told AFP.
He believes barocaloric solids have the potential to be as efficient as gas, if not more so.
“But whatever we introduce as new technologies always has to hit the basic requirements,” which include being compact and quiet enough for use in homes and cars, he said.
Alongside his research at Cambridge, Moya founded the startup Barocal in 2019 to turn his research group’s discoveries into tangible products.
It employs nine people and has its own laboratory, which is currently a modest container in a parking lot.
But the startup is attracting interest and in recent years has raised around €4 million ($4.5 million), notably from the European Innovation Council — an EU program involving the UK — and Breakthrough Energy, an umbrella group of initiatives founded by US billionaire Bill Gates to reduce greenhouse gas emissions.
It plans to increase its workforce to 25 or 30 this year.
The first air-conditioner prototype is the size of a large suitcase and hums quite loudly when a hydraulic circuit increases or decreases the pressure inside the four crystal-filled cylinders. But it works.
A small refrigerator is attached to the system, and the cans of soda inside are perfectly chilled.
– Cheaper bills –
The prototype has “not really been optimised yet for either mass, volume, or even sound”, acknowledged Mohsen Elabbadi, a materials engineer at Barocal.
But the performance of the units they are working to perfect will eventually be comparable with those running on gas, he promised.
While the company is currently focusing on cooling, the technology could also be used to produce heat.
Several teams are studying these materials around the world, but the Cambridge team is a pioneer in the field, according to Breakthrough Energy, which estimates that these devices have the potential to reduce emissions by up to 75 percent compared with traditional units.
Barocal hopes to launch a first product on the market within three years, according to commercial director Florian Schabus.
These will initially be cooling units for “large shopping centres, warehouses, schools” and even “data centres”, he said.
The company reasons that the ultimate promise of cheaper bills will convince businesses to stump up the higher initial costs.
Barocal is eventually aiming for retail prices similar to traditional units, allowing it to launch in the residential market.
As world heats up, UN cools itself the cool way: with water
By AFP
May 11, 2025
As more people want to stay cool in a planet that is steadily heating up, energy experts point to water-based system as a good alternative - Copyright AFP ANGELA WEISS
Amélie BOTTOLLIER-DEPOIS
Deep in the bowels of the UN headquarters, a pump sucks in huge amounts of water from the East River to help cool the complex with an old but energy-efficient mechanism.
As more and more people want to stay cool in a planet that is steadily heating up, energy experts point to this kind of water-based system as a good alternative to air conditioning. But in many cases they are hard to set up.
The system has been part of the New York complex since it opened in the 1950s, chief building engineer Michael Martini told AFP during a tour of the cooling equipment.
The system, overhauled with the rest of the complex from 2008 to 2014, cools the UN center using less energy than a conventional air conditioning system. UN policy is to bring the air temperature down to about 24 degrees Celsius, or 75 degrees Fahrenheit.
In summer in New York, the river running beside the UN headquarters — it is actually a salt water estuary — stays much cooler than the surrounding air, which can reach 100 degrees. So cooling the building eats up less energy.
As many as 26,000 liters per minute (7,000 gallons) of water flow through fiber glass pipes to the complex’s cooling plant, which uses it and a refrigerant gas to produce cold.
The system has two independent loops to prevent contamination of the water that flows back into the river at a higher temperature, said the head of the cooling system, David Lindsay.
Looking at the gleaming glass tower of the UN headquarters and the dome of the General Assembly, you would never know that the East River serves this purpose for the UN and is more than just part of the scenery.
The UN’s New York headquarters is not its only building that depends on water.
In Geneva, its Palais de Nations features a cooling system that uses water from Lake Geneva. And the UN City complex in Copenhagen, which houses 10 UN agencies, depends on cold seawater that almost eliminates the need for electricity to cool the place.
This a huge benefit compared to the estimated two billion air conditioning units installed around a world.
– Why so rare? –
With the number of air conditioners due to increase so as to help people who are more and more exposed to dangerous temperatures, energy consumption for the purpose of cooling has already tripled since 1990, says the International Energy Agency, which wants more efficient systems.
Examples of these are centralized air conditioning networks using electricity, geothermal systems or ones that use water, like the UN complex in New York.
This latter system “has not been deployed as much as it should be for the issues we face today,” said Lily Riahi, coordinator of Cool Coalition, a grouping of states, cities and companies under the aegis of the United Nations.
Some big organizations have been able to run such systems on their own, like the United Nations or Cornell University in New York State, which relies on water from Lake Cayuga.
But for the most part these systems require a lot of coordination among multiple stakeholders, said Riahi.
“We know it’s technically possible, and we know actually there are many cases that prove the economics as well,” said Rob Thornton, president of the International District Energy Association, which helps develop district cooling and heating networks.
“But it requires someone, some agent, whether it’s a champion, a city, or a utility or someone, to actually undertake the aggregation of the market,” he said.
“The challenge is just gathering and aggregating the customers to the point where there’s enough, where the risk can be managed,” Thornton said.
He cited Paris as an example, which uses the Seine River to run Europe’s largest water-based cooling grid.
These networks allow for the reduced use toxic substances as coolants, and lower the risk of leaks.
And they avoid emissions of hot air — like air conditioning units spew — into cities already enduring heat waves.
But hot water from cooling units, when dumped back into rivers and other bodies of water, is dangerous for aquatic ecosystems, environmentalists say.
“This challenge is quite small, compared to the discharge from nuclear plants,” said Riahi, adding the problem can be addressed by setting a temperate limit on this water.
Indians buy 14 million ACs a year, and need many more
By AFP
May 11, 2025
A record 14 million AC units were sold in India last year, with a ninefold increase in residential ownership forecast by mid-century - Copyright AFP Sajjad HUSSAIN
Abhaya SRIVASTAVA
Aarti Verma is about to join the growing ranks of Indians installing air conditioning, scraping together savings to secure relief from sometimes deadly temperatures that can reach nearly 50 Celsius.
A record 14 million AC units were sold in India last year, with a ninefold increase in residential ownership forecast by mid-century. That will give millions safer and more comfortable conditions at work and home.
But it will also drive demand for electricity that is generated mostly by burning climate-warming coal, and increase the hot AC exhaust air expelled into the country’s stifling streets.
For Verma, the priority is securing some immediate relief.
Her sales and marketing work means she must visit multiple stores a day, battling blazing heat.
“Coming home after a long day I want some comfort,” said the 25-year-old, who earns 30,000 rupees ($350) a month and will pay 50,000 rupees ($584) to install air conditioning in her spartan two-room home.
“Earlier I would sleep on the terrace, but these days it’s so hot even in the night, AC has become a necessity,” she told AFP in a poor neighbourhood of the capital Delhi.
India is the world’s fastest-growing AC market, despite only about seven percent of households currently owning units.
The boom could mean the world’s most populous country needs to triple electricity production to meet demand, experts say.
The nation of 1.4 billion people is already the world’s third-biggest producer of climate-warming greenhouse gases, burning through one billion tonnes of coal in 2024-25, according to a government statement.
– Brutal summer –
“AC penetration across India is primarily driven by weather conditions, a growing middle class, favourable consumer financing options and widespread electrification,” said K.J. Jawa, the India chief of Japanese AC manufacturer Daikin.
“Today, ACs are no longer regarded as a luxury indulgence, but a productivity and need investment –- as a good night sleep is imperative for our mental and physical wellness,” he told AFP.
Verma had to pay 13,000 rupees ($150) as a down payment, with the rest divided over monthly instalments.
“I could have bought gold with that money which would have been a good investment but I gave priority to the AC,” she said.
According to the meteorological department, 2024 was India’s hottest year since thorough records began in 1901, with sizzling temperatures following a global pattern of extreme weather driven by climate change.
A heatwave in May 2024 in New Delhi saw temperatures match the capital’s previous record high: 49.2 Celsius (120.5 Fahrenheit) clocked in 2022.
The brutal summer heat can melt tarmac on the roads and puts millions of people at risk, with nearly 11,000 people dying due to heat stroke in India between 2012 and 2021, according to government data.
Public health experts say the true number of heat-related deaths is likely in the thousands but because heat is often not listed as a reason on a death certificate, many casualties don’t get counted in official figures.
Ironically, the refrigerants inside AC units and the coal-generated electricity that powers them only exacerbate global warming. Widespread AC use also raises outdoor temperatures by expelling indoor heat.
Studies — including by the World Health Organization and UN-Habitat — show that the heat-generating motors inside AC units can themselves push up temperatures in urban areas by a degree Celsius or more.
– Energy ratings –
Before buying an AC, Verma relied on a traditional air cooler — a noisy fan-run device that blows cool air off water-soaked pads.
But filling the cooler with water and making sure it did not become a haven for disease-carrying mosquitoes required great effort.
Sales are brisk at Imperial Refrigeration in Delhi’s old quarters, with a steady stream of customers braving the afternoon heat.
Japsahib Singh Ahuja, 22, whose family owns the 50-year-old business, said sales have more than tripled in the last five years, thanks to first-time consumers and AC “replacement cycles”.
“ACs these days don’t last long, because there are so many pollutants in Delhi air that lead to corrosion and gas leakage from the equipment,” he explained.
Delhi and the surrounding metropolitan area, home to more than 30 million people, consistently top world rankings for air pollution.
Air conditioning will account for a quarter of India’s emissions and nearly half nationwide peak electricity demand by 2050, according to the UN Environment Programme’s Cool Coalition.
But India has so far declined to sign up to the coalition’s Global Cooling Pledge to reduce the sector’s climate impact.
Still, there are signs of hope, with Indians increasingly buying energy-efficient AC units, according to Ahuja.
Energy-saving inverter ACs now dominate the market, and companies set a default temperature of 24 degrees Celsius.
“Energy ratings are now mandatory,” said Ahuja. “We will surely see long-term benefits.”
