When you think of Facebook and “hot air,” a stream of pointless online chatter might be what comes to mind. But the company will soon be putting its literal hot air — the waste heat pumped out by one of its data centers — to good environmental use. That center, in Odense, Denmark, plans to channel its waste heat to warm nearly 7,000 homes when it opens in 2020.

Waste heat is everywhere. Every time an engine runs, a machine clunks away, or any work is done by anything, heat is generated. That’s a law of thermodynamics. More often than not, that heat gets thrown away, dribbling out into the atmosphere. The scale of this invisible garbage is huge: About 70 percent of all the energy produced by humanity gets chucked as waste heat.

“It’s the biggest source of energy on the planet,” says Joseph King, one of the program directors for the U.S. government’s Advanced Research Projects Agency-Energy (ARPA-E), an agency started in 2009 with the mission of funding high-risk technology projects with high potential benefit. One of the agency’s main missions is to hike up energy efficiency, which means both avoiding making so much waste heat in the first place, and making the most of the heat that’s there. ARPA-E has funded a host of innovative projects in that realm, including a $3.5 million grant for RedWave Energy, which aims to capture the low-temperature wasted heat from places like power plants using arrays of innovative miniature antennae. 

Read more at Yale Environment 360