Scaling Carbon Capture
One of the most important problems to work on at this point in history.
- As solar power gets cheaper and oil becomes more scarce, at some point this decade it will be cheaper to electrically extract carbon from the air than to drill holes in the earth's crust
- We ideally want a Haber's process for carbon dioxide
- CO$_2$ is usually a by-product, and it can't be used for fuel anymore than any other fully oxidized stable chemical can.
- We need to put back the energy that was released when it was produced. And then some more to remove the oxygen atoms.
- Sabatier reaction:
catalytically react CO$_2$ with
hydrogen, producing methane (CH$_4$) and water vapour.
- Doing this requires a very large supply of pure hydrogen, ideally generated electrolytically, which requires an enormous supply of electricity.
- $\Delta H=-165.0$ kJ mol$^{-1}$
- This happens at very high temperatures, so $T\Delta S$ is very high and $\Delta G$ will be positive
- Overall efficiency is at 15% to 35% at best.
- Three big challenges
- CO$_2$ concentration
- CO$_2$ reduction
- Electricity Cost