Some 190 nations agreed to phase out refrigerants that are also powerful greenhouse gases in the coming years in a deal hammered out over the weekend in Kigali, Rwanda.
The global pact will see developed nations peak their use of hydrofluorocarbons (HFCs) in 2019. A compromise clause allows developing countries a later starting date of 2024, while a handful, including India and Pakistan will not have to begin their work eliminating HFCs until 2028.
HFCs, chemicals that are often used in refrigerators, air conditioners and automotive cooling systems, were originally introduced as a replacement for chlorofluorocarbons (CFCs). In 1987, countries agreed to the Montreal Protocol, which oversaw the elimination of CFCs, which were responsible for depleting the Earth’s ozone layer, that part of the stratosphere that absorbs much of the sun’s harmful ultraviolet radiation. Due to the protocol’s success, the hole in the ozone layer is now recovering and models project that it will be restored between 2050 and 2070.
However, while HFCs have no negative impact on ozone because they do not contain chlorine, these latter substances are also GHGs about a thousand times more powerful than carbon dioxide. The use of HFC emissions has been growing by seven percent a year, largely a result of the growing middle classes of emerging economies now being able to afford air conditioning.
The Kigali deal formally endorses a tentative agreement to eliminate HFCs that had been reached in March that offered a four-year deadline extension to 34 countries where average temperature reach 35°C or higher for at least two months of the year, mostly in the Middle East and North Africa. But the final deal was only achieved by offering a further extension of the grace period, to allow poorer nations the time to invest in new coolant technologies, plants and equipment – steps that wealthier nations have already taken.
There are a number of alternatives, including hydrocarbons, ammonia and CO2. But not all alternatives are equally attractive to manufacturers in different sectors.
PICS has helped fund research into some of these options. One possibility for the automotive sector involves ‘adsorption cooling systems’. Adsorption is the process whereby atoms or molecules from a gas or liquid stick to the surface of a material (distinct from absorption, wherein a fluid is dissolved by a liquid or solid). Currently, cars and trucks use vapour compression refrigeration and air conditioning systems. But these use HFCs and they also require large amounts of electricity.
Adsorption cooling systems would use a more climate-friendly refrigerant such as water that is adsorbed by a porous material, and in so doing, delivering the desired cooling via evaporation. The trick though has been to discover new materials that both have a high adsorption capacity and are very good at transporting heat away. A range of test materials has been trialled, with researchers narrowing in on robust solution in the last year. More details will be released in the coming months.
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