The Fight for Clean Air Has Many Fronts. One of Them Is Algae.

The device on Rehaan Lulla’s desk looks like a lava lamp. A tall glass column, a slow swirl of green and a soft glow. What it is invisibly doing is drawing carbon dioxide out of the room and releasing oxygen more efficiently than the pot plants most people keep for the same reason. The organism inside is microalgae, grown for decades as food and as a cosmetics ingredient, which Rehaan’s start-up AlGreen has repurposed to clean the air.