As it becomes increasingly clear that legislating carbon emission cuts will be almost impossible in the immediate future—while counting on research for new energy solutions is an inevitable gamble—the possibility of geoengineering is going from a pipe dream to a last-ditch weapon. Most geoengineering schemes would involve trying to directly cool the planet’s climate—usually by pumping aerosols into the atmosphere that would deflect sunlight and compensate for an intensified greenhouse effect. But direct geoengineering would be fraught with risk because the climate is incredibly complex, and tweaking with one aspect of the system could have side effects we have no way of preparing for—which is why some at the Convention on Biological Diversity meeting are reportedly pushing for a ban on geoengineering research.
But if there were a way to directly remove excess carbon dioxide from the atmosphere and store it, we might be able to geoengineer safely and precisely. The key is to find a way to suck CO2 out of the atmosphere economically—and scientists from India have found an unexpected solution, possibly over breakfast. According to a study in the International Journal of Global Warming led by Basab Chaudhuri of the University of Calcutta, the membrane of an eggshell can absorb almost seven times its weight in carbon dioxide—and once the gas is trapped, it can be stored. Here’s how it works: an eggshell is made of three layers—a cuticle on the outside, a calcium-containing middle layer and an inner layer. Those second and third layers are made of protein fibers bonded to calcium carbonate. That membrane is incredibly thin—just 100 micrometers thick—but a weak acid can be used to separate the membrane from the shell, after which it can then be used as a carbon dioxide absorbant.
Obviously while an eggshell may be able to absorb seven times its weight in CO2, of course eggshells themselves don’t exactly weight a lot, so each egg could only absorb a tiny amount of the gas. But the U.S. alone consumes around 75 billion eggs a year, and that’s just a slice of the global egg market, which is dominated by China. The study authors point out that we would need to develop an industrial system for separating eggshells before this method could be used to actually take CO2 out of the atmosphere—and of course, if that system used a great deal of energy, it might end up producing almost as much CO2 as it absorbs. (That’s energy equation has so far held back most efforts at air carbon capture, like Columbia University physicist Klaus Lackner’s carbon scrubbers.) Still, the egg study shows that there could be solutions right in front of us—poached, fried or scrambled.
