> I do remember stories from undergrad engineering about the development of the first moon landing and the associated technologies.

Of course. However, in all of those cases you could go through the math in a brutally honest manner and determine that things were realistic within a certain margin of error given physics constraints.

The issue I have with every single proposal I have seen is that they are, to put it in a certain way, dishonest. It's the equivalent of "and then a miracle occurs" being reported as a real solution.

In this particular case, I would not have funded this research without first funding an initial (much lower cost) study to prove that the project meets basic physics. If, and only if, the researchers can prove the solution is actually realizable without causing damage, etc. We move to the next phase.

So, now you know it can be done without causing more damage and the numbers add-up.

Phase 2 would entail what I call a "sense of proportion" report. Again, much cheaper than funding the entire experiment.

What is that?

Before you launch into anything you need to understand what impact it might have if you succeeded at deploying it in the most optimal form imaginable. From there you grade it on a curve and try to estimate what reality might be. Is reality +/- standard distributions from the reported optimal value or worse?

The report would also have a "Comparables" section. Using language we use in the US when a home is appraised. Realtors find similar homes and look at how much they sold for to then compute the value of the home they are selling. This attempts to ensure that the home is sold for a reasonable price, not too low, not too high.

The "Comparables" report would compare the proposal to alternatives. In engineering it is always interesting to suggest new solutions to a problem. However, you always have to consider the alternatives or you risk wasting your time and money.

In this case the comparables might be what I mentioned in my original comment: One of the figures of merit they mention in the paper is CO2 reduction equivalent to removing 350K internal combustion (IC) cars from the roads. OK. Great. The question to ask, then, is: Can we achieve the same or better performance using other solutions, existing or under evaluation?

In the case of cars the obvious thing to look at is the replacement of IC cars with electrics. You have to evaluate that solution against the proposal before moving forward. Why? Because it is a real solution with real metrics we understand far better than a science experiment.

If all of the above and the comparison to known solutions shows the project might have merit within an acceptable margin of erro, and only if that is the case, then it gets funded and the required research begins.

Until all of the above passes basic math and physics, the entire thing is a big hand-wavy "and then a miracle occurs" fantasy. I am sorry to say that most of what has been proposed in this domain is nothing more than that, fantasies. Expansive fantasies that nobody ever seems to want to rigorously evaluate, as if reality didn't matter at all.

I want real solutions. I don't want us to waste time and money on fantasies, which is what we seemed to be doing. BTW, lots of money in the fantasy business these days. Maybe I should join them. It would sure be far more profitable than trying to point out the emperor has no clothes [0].

Just based on the downvotes and comments over the years on this topic, it is obvious to me, using HN as a sample of people who should be smart critical thinkers, that something is wrong. Perhaps people are so emotionally invested in the subject to forget that the very first job in science is to demand (and offer) proof of hypothesis based on the scientific method. This, among other things, requires full disclosure as well as the ability for anyone to verify and reproduce claims.

In this case, there should have been an entire section --pages-- on this report with an honest appraisal of mining, processing and delivery timelines, feasibility and consequences to the environment. Without that sort of thing it's like me showing a super efficient machine without disclosing that I am not accounting for additional energy being supplied from outside the system. Looks great. Dishonest as hell.

[0] For those who might not understand the relevance of the reference to the story by Hans Christian Andersen:

https://en.wikipedia.org/wiki/The_Emperor%27s_New_Clothes

From the article:

"Two swindlers arrive at the capital city of an emperor who spends lavishly on clothing at the expense of state matters. Posing as weavers, they offer to supply him with magnificent clothes that are invisible to those who are stupid or incompetent. The emperor hires them, and they set up looms and go to work. A succession of officials, and then the emperor himself, visit them to check their progress. Each sees that the looms are empty but pretends otherwise to avoid being thought a fool.

Finally, the weavers report that the emperor's suit is finished. They mime dressing him and he sets off in a procession before the whole city. The townsfolk uncomfortably go along with the pretense, not wanting to appear inept or stupid, until a child blurts out that the emperor is wearing nothing at all. The people then realize that everyone has been fooled. Although startled, the emperor continues the procession, walking more proudly than ever."