Emerging Voices: What to Do with Captured Carbon

Carbon dioxide is a frustratingly inert molecule. The two carbon-oxygen covalent double bonds, with their 180-deg. bond angle and low-energy state, make it so that any process intended to transform CO₂ into a useful product faces a steep thermodynamic barrier. Unfortunately, atmospheric carbon is also the leading cause of global climate change, with humans releasing tens of billions of tons of the gas each year.

In the long term, direct air capture (DAC) systems could provide one possible route out of our climate quagmire. More traditional carbon capture systems, which scrub CO₂ from fluegas streams before it is released into the atmosphere, are installed in many coal fired power plants. Similar systems have been employed in steel and cement production facilities. However, the glut of CO₂ that is likely to accrue as the result of these expanding technologies leaves engineers with the new problem of what should be done with it.

The commonly espoused solution is to sequester the carbon underground, possibly using the spent subterranean reservoirs left after oil drilling. However, questions about containment integrity, difficulty understanding and quantifying storage volumes, unintended chemical reactions, and induced seismicity have slowed down the development of such carbon-sequestering projects and have sent engineers, at least for the time being, back to the drawing board. This article describes a few unique uses for carbon that intrepid chemical engineers have devised so far.

Fuels. With CO₂ being such an unreactive molecule, transforming it into a combustible fuel source is not a particularly intuitive solution...