Capturing carbon from the air and sequestering it is emerging as a viable strategy, and now scientists have developed a new method to turn CO2 gas back into solid coal, that can then be buried, or even used for electronic components.

Many projects are currently experimenting with new ways to capture carbon from the point of emission. The gas is run through and absorbed by metal-organic frameworks, porous powders, bubble-like membranes, or materials made of clay or coffee grounds.

But that's only half the story – what do you do with that captured carbon? After it's extracted from those capture materials, the gas can then be reused to make concrete, fizzy drinks or fuels, or in larger amounts it can be stashed away underground. To store CO2, it's usually compressed into a liquid form or bonded with water, and then injected deep underground. There, it interacts with basalt rock and solidifies into a carbonate mineral, reportedly in as little as two years.

But other studies have found that this process may not be as effective as it seems. An MIT investigation found that only a thin top layer was turning solid – underneath was still a large pocket of gas. That keeps it out of the atmosphere for now, but has the potential to leak in the future and release it all back into the air, undoing all our hard work.