Creating the tons of steel and concrete we use to build our world requires a massive amount of heat—and most of it comes from burning dirty fossil fuels. HelioHeat cleans up that process by using the power of the sun. Here’s how it works: A field of 100,000 motorized, computer-­controlled mirrors concentrates sunlight in the direction of a 40-m-tall tower, “like a giant magnifying glass,” says Heliogen founder Bill Gross. There, a hot spot gets up to 2,000°F, where the heat can be harnessed to melt steel or make cement or electricity. Future iterations of the tech, says Gross, could use the sunlight to create hydrogen to power zero-emission automobiles. —Jesse Will

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