After three years of record-breaking heat, this one is set to be yet another scorcher. Air-conditioning? Not going anywhere. The International Energy Agency projects that the number of AC units will triple by 2050.
That’s good for health—one Lancet study estimated that AC prevented nearly 200,000 premature deaths in 2019 alone—but bad for the planet. Artificial chill already accounts for 7% of global electricity use and 3% of greenhouse-gas emissions, and if improperly disposed of, the units can leak refrigerants with more global-warming potential than carbon dioxide.
Feeling the heat, a number of scientists and startups are hoping to amp up solid-state cooling, which is currently used at a small scale for things like mini fridges, EV batteries, and some high-end gaming computers. Tra