[jaycroft]

"Carbon is extracted from the air in the form of CO2 and combined with the hydrogen in a process called synthesis."

It seems like at least re-burning the carbon that's already in the air is better than burning new dug up carbon? This is at least not net atmospheric carbon positive. You can do sequestration too...

[Tsiklon]

I am by no means a chemist (beyond a secondary school level), but burning CO2 doesn’t seem possible. Doesn’t burning through application of some energy split the bonds of complicated stable molecules into less complicated, but stable molecules (by adding oxygen), thus releasing energy.

In this case; how do they recombine the CO2 into more complicated hydrocarbons? And if it’s energy negative, is it better to do this, or to use it to capture carbon?

[deeviant]

> In this case; how do they recombine the CO2 into more complicated hydrocarbons?

Fischer–Tropsch process.

> And if it’s energy negative, is it better to do this, or to use it to capture carbon?

It's obviously "energy negative", as it would be a violation of thermodynamics for it not to be, entropy being how it is. As far as doing it over carbon capture, I would be more interested in hearing your thoughts on why carbon capture would be a better alternative.

[jaycroft]

"In this case; how do they recombine..." that is exactly what the article is about. E-fuels are atmospheric carbon dioxide that is electrolyzed using renewable sources and combined with additional hydrogen in order to produce octane. So, my original parent is saying the process we should focus on is sequestration (Atmospheric carbon dioxide -> electrolyze to carbon and oxygen [this is the energy intensive step] -> bury the carbon and leave the oxygen -> harvest natural hydrocarbons / oil -> distill into various weights -> burn the octane). I propose achieving similar atmospheric carbon balance with similar energy inputs with the cycle (Atmospheric carbon dioxide -> electrolyze to carbon and oxygen [same energy per carbon] -> hydogenate the carbon to octane for portability and compatibility reasons -> burn the octane). The only point in doing all of this of course is the huge installed user base for engines that burn octane, a portable and stable fuel.

[xattt]

There’s no possible way the process for carbon sequestration and fuel synthesis would use less e-fuel.