I am being downvoted because I tried to make the point as succinctly as I could. It turns out, stating something with childish simplicity doesn't sound smart.

I am being downvoted because I tried to make the point as succinctly as I could. It turns out, stating something with childish simplicity doesn't sound smart. I am also being downvoted because as other comments have noted, their intuition states that the solution could have a margin positive net impact versus the externalities associated with industrial concrete production. And according to the doctrine of technology solutionism, which is the doctrine of most people who read HN (myself included sometimes), the onus is frequently on the skeptic to show through rational analysis that the innovative solution has greater harm than benefit, while the believers in the innovative solution are allowed to suspend doubt and use their intuitive judgement to rationalize the relative efficacy of the solution at hand. It's like the technologists' version of Bertrand Russell's Teapot.