What a great idea. Engineering can be so cool. “parasitic robots,” as their creators NAS-DRA call them, perch on unlit neon signs during the day, sucking up carbon dioxide through a coating into their spread wings. At night, when the neon signs light up, that heat activates the coating at a certain temperature and releases the CO2 for plants grown via hydroponics on the drones’ now folded-up wings. The gas can also be collected for future use as energy, as we’ve mentioned before, or even for use in plastic feedstocks.