Below are my full comments to the reporter. Note that in the comments below I refer to the paper as Herzog et al. below, Herzog is the last author on the paper and a long-time critic of chemical air capture. Herzog calls his academic opponents "snake oil salesmen" and argues that his paper will help to argue against those who say "you don’t have to change anything about your lifestyle" to reduce greenhouse gases.
I have bolded the parts of my correspondence to the reporter which were quoted in the USA Today article:
This paper is the latest in an ongoing and healthy debate between academics who think that chemical air capture will be less expensive (David Keith, Klaus Lackner) and those who think it will be more expensive (Herzog et al.). This debate has been going on in the literature for a while. Like a lot in the climate debate there is thus something there for everyone.
I am not an engineer nor do I have a horse in this race, but I will say that insofar as engineering projects are concerned debates about costs are best resolved through experience not theory. So if Keith and Lackner can build an air capture process that is cheaper than argued by Herzog (which they are trying to do), they win the debate, and if they can't, then Herzog wins. I do know that our record of technological forecasting in many areas, especially as related to costs, has never been very good, so I take all such studies with a grain of salt.
More generally, chemical air capture, as described by Herzog et al. is only one potential technological approach to air capture -- there are also other chemical processes discussed in the literature, and even biological approaches and geological approaches. So the infeasibility of any one approach doesn't doom the whole enterprise of trying to brute force remove CO2 from air.
In the future, we may indeed one way want to remove CO2 from the air using such brute force methods, and cost will certainly a key variable in that decision. But from where I sit, debates over cost will be decided by real world technologies not academic papers. That said papers such as Herzog's are welcome and important because they do help to shape what technologies are tested and what bars of performance they are expected to meet (and not meet).
Finally, Herzog et al. reach the same conclusion that I do in my book The Climate Fix -- regardless of the costs of chemical air capture, to have any hope of stabilizing carbon dioxide levels in the atmosphere at a low level requires the near complete decarbonization (a real word;-) of our energy production system.
If unclear or you have a follow up just let me know!
All best,
Roger