Air play: Could we capture carbon from the atmosphere?
Working at the Los Alamos National Laboratory during the 1990s, Klaus Lackner had numerous interests: the behavior of high explosives, nuclear fusion, and self-replicating machine systems. At some point, he turned his attention to the technology used to capture CO2 from the smokestacks of coal plants — technology in which the U.S. government has invested billions of dollars, with little to show for it. He began to wonder whether it might make more sense to scrub CO2 from the atmosphere. So when his daughter Claire asked for help with a science project, he asked her: “Why don’t you pull CO2 out of the air?”Chemical engineers have known for decades that sodium hydroxide, a caustic base also known as lye, will bind with CO2, an acid, to make carbonates.
That’s basically how CO2 is removed from the air so people can continue to breathe on submarines or in spaceships. Claire accomplished the feat by filling a test tube with a solution of sodium hydroxide, buying a fish-tank pump from a pet store, and running air through the test tube all night. By the next day, some of the sodium hydroxide had absorbed CO2, creating a solution of sodium carbonate.“I was surprised that she pulled this off as well as she did,” Lackner recalls, “which made me feel that it could be easier than I thought.”
Duly inspired, Lackner set off on a quest to design a machine to pull CO2 out of the air. This would seem to be much harder than collecting carbon dioxide from the smokestacks of power plants that burn coal or natural gas, where concentrations of CO2 are about 12 percent for coal or 4 percent for natural gas. Less than 0.04 percent of the air is CO2. Still, in a presentation called “Carbon Dioxide Extraction From Air: Is It An Option?” that he wrote in 1999 with Hans-Joachim Ziock, a colleague at Los Alamos, and the late Patrick Grimes, an expert in chemical processes, Lackner identified an important role for air-capture technology: