Solar thermal collectors on a hotel's roof near Zion National Park in Utah.

Solar thermal collectors on a hotel’s roof near Zion National Park in Utah.

By XiaoZhi Lim

At Hotel Star Sapphire in Dawei, Myanmar, guests sip from coconuts in cool, air-conditioned comfort as the steamy tropical night rolls on. Seven thousand kilometres to the west, in dry Khartoum, Sudan, patients rest in a United Nations Hospital, cocooned from the baking desert heat.

In both buildings, the pleasant conditions come courtesy of air-conditioning units that rely in part on dark glass tubes that turn sunlight into cooling power. These aren’t the familiar solar panels that harvest light to make electricity. Instead, they harness heat from the Sun to chill buildings through a neat bit of thermodynamic sleight of hand. Researchers and some energy experts say that this form of cooling — known as solar thermal — could help to slake the growing global demand for fuel to run energy-hungry air conditioning. The Intergovernmental Panel on Climate Change predicts that by 2100, the need for electricity to power cooling will have surged to more than 30 times what it was in 2000.

Hopeful that solar-thermal technology is nearing a crucial turning point, research groups are showing off their systems at a growing number of hotels, shopping centres and other buildings across the world. Today, there are some 1,200 installations — more than 10 times the total from a decade ago. Companies that produce solar-thermal chillers say that they use 30–90% less electricity than the conventional air conditioners that operate in most buildings, depending on the type and size of the installation. And researchers are working to make the systems more efficient and cheaper to build.


Continue reading at Nature. Originally published on January 31, 2017.

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