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 kilometers 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.

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