In the summer of 1902, New York was groaning under a record heatwave. This also caused problems for machines. Due to the high temperatures and humidity, the paper in a print shop in Brooklyn warped to such an extent that production was no longer possible. The print shop commissioned the 25-year-old mechanical engineer Willis Carrier to remedy the situation. Carrier delivered. He developed a system in which fans blew the warm, humid room air over evaporator coils filled with ice-cold water. Cold, dry recirculating air was the result. The first modern air conditioning system had been invented.
The need for cooling is increasing
Today, according to estimates, around two billion appliances worldwide are cooling air—and have gone from being the solution to being part of the problem. Air conditioning systems account for around ten percent of global electricity consumption and around three percent of greenhouse gas emissions. And the demand for cool air is growing. The International Energy Agency estimates that the number of air conditioning systems will triple by 2050. We therefore urgently need more efficient and environmentally friendly cooling technologies.
Cooling using the elastocaloric effect is considered to be one of the most important alternatives. Materials that display this effect—such as nickel-titanium alloys and some polymers—absorb heat from the environment and release it as soon as they are exposed to external stimuli. These stimuli include magnetic pulses, pressure, mechanical tension, and electric fields. This technology works entirely without climate-damaging refrigerants. This is one of the reasons why the U.S. Department of Energy and the European Commission regard elastocaloric cooling as one of the most important alternatives to vapor compression. The World Economic Forum calls this form of cooling one of the “Top 10 Emerging Technologies.”
Membrane heat pumps offer another way of cooling rooms efficiently and sustainably. They are equipped with a selectively permeable membrane for heat transfer. In the electrochemical version, an electrical voltage generates ion transport which drives the liquid compression and thus the cooling. In the sorption-based heat pump, vapor is passed through a membrane to separate an absorbent (e.g. a salt solution) from a refrigerant and thus create cooling. Both systems use liquids that release hardly any greenhouse gases.
A Liquid solution
Even NASA has entered the race for the most advanced air conditioning system. The U.S. space agency recently founded the company Helix Earth. This company aims to halve the energy consumption of air conditioning systems by equipping conventional vapor compression units with liquid desiccants for pre-dehumidification.
In the future, there will be a variety of ways to keep a cool head and protect the environment at the same time. Progress in this area is urgently needed, because one thing is certain: Rising temperatures worldwide will increase the need for cool rooms. That’s why Foresight is analyzing this topic as part of the “GameChanger 2035” project with a view to future potential for Evonik 
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