CO2 sequestration through accelerated weathering of limestone on ships

Here's a summary of the themes expressed in the Hacker News discussion:

Skepticism towards Geoengineering and Carbon Sequestration Proposals

Many participants express significant skepticism regarding the feasibility, effectiveness, and practicality of proposed geoengineering and carbon sequestration techniques, particularly those involving exotic or large-scale methods. There's a general sentiment that these solutions are often overly simplistic, inadequately researched, or economically or logistically impossible to implement at the required scale.

"Geoengineering is currently mostly BS idealism." - Joel_Mckay
"This is a very shallow analysis, feels like an undergrad wrote that." - colechristensen
"Could there be any possible negative effects from an 81 gigaton nuke exploding though?" - joegibbs
"The underlying problem for all this is the time value of money/capital." - Terr_
"The reason why this and many other CO2 sequestration techniques don't work to solve the carbon pollution problem is that they always measure 'gains' on a very narrow context, irl the inputs to the system incur some carbon emissions as well." - moralestapia
"No. Not even a little bit." - deadbabe (regarding whether any known approach to CO2 sequestration can make a difference)
"It should be made a crime to mention CO2 sequestration when sane avenues (short of geoengineering) like large scale (night activated) radiatively-cooled floating solar panels, or roads are more likely to help (& even be profitable)" - gsf_emergency_2
"verisimi: I don't get it. A solution for co2 is to carry extra stone on a ship for 10 years? It sounds like a bad joke."

The Primacy of Reducing Fossil Fuel Consumption

A strong recurring theme is the argument that the most effective and only truly practical solution to climate change is to drastically reduce or eliminate the burning of fossil fuels. Many believe that focusing on sequestration or geoengineering diverts attention and resources from this fundamental necessity.

"The absolute best way to decrease the amount of atmospheric CO2 over time is to keep fossil fuels in the ground." - crystal_revenge
"In general, renewable carbon free energy sources are the only practical options, and have even proven economically beneficial in many places." - Joel_Mckay
"If we could store energy cheaper than we could use it we'd have a perpetual motion machine, I think? Fairly sure this would be physically impossible. Where this might be wrong is if we found a process to use another energy source (the sun, something that uses the sun, etc) to do it for us, but we haven't go anything that works in that vein either." - graeme
"It's about 10 times cheaper to not burn fossil fuels than to sequester" - yread

The Challenge of Scale and Energy Requirements

The sheer scale of the climate problem and the immense energy requirements for any meaningful carbon sequestration are highlighted as major barriers. Several users discuss how even seemingly promising methods face insurmountable hurdles when considering the amount of material, energy, and infrastructure needed to make a global impact.

"The data driven conclusion is exhausting every mine on every landmass would only buy another 5 to 7 years at most." - Joel_Mckay
"If you account for (just off the top my head): Grinding the limestone down to dust, Limestone transport from wherever is sourced to the ships, Extra weight of limestone on the ship... You might be emitting much more carbon than the one your system was designed to absorb." - moralestapia
"Is there any known approach to CO2 sequestration that could reach a scale that would even remotely make a difference for climate change? They either require an enormous amount of energy and/or machinery and/or space." - vjvjvjvjghv
"It is exceedingly likely that any sequestration will take substantially more energy than burning fossils fuels produced." - graeme
"To avoid any concerns about scalability, as well as about energy supply intermittency, I made my estimate using only the oldest process in the chemical industry, lime burning, which predates plastics, oil drilling, steel, iron, bronze, writing, cities, ceramic, and possibly even agriculture." - kragen (discussing the scale of lime production for carbon capture)

The Inevitability of Climate Change Impacts and Adaptation

Some contributors adopt a more fatalistic or pragmatic view, suggesting that significant warming is already locked in, necessitating adaptation rather than solely relying on mitigation or unproven sequestration technologies. They also touch upon the long-term perspective of Earth's recovery independent of human intervention.

"We have already had about 1.4C of warming, which is too much for humans near the equator given how hot it already was. It's either that or migration away from the equator, pick one." - energy123
"The planet will be fine again in 30 thousand years or so, after the current population of psychotic primates go extinct. It is ultimately a self-correcting problem regardless of what humans collectively choose to do." - Joel_Mckay
"Good and evil don't really apply to inescapable facts. The earth was fine without humans before we arrived, and will likely continue on after our species is gone." - Joel_Mckay
"Burning carbon is effectively debt. If we stopped burning carbon right this second, billions would die, as our whole system depends upon it. But if we don't stop burning it, we increase our future problems. This is unpleasant to reckon with so most don't. I don't think it makes the problem intractable, but it gets harder the more we delay." - graeme

The Distinction Between Science and Engineering / "Smart" Ideas

A point of discussion emerges around distinguishing between theoretical scientific possibilities and practical engineering realities. Some argue that certain proposals, while scientifically interesting, are not yet (and may never be) engineering solutions due to practical constraints, cost, or unforeseen side effects. The term "smaht" is used pejoratively to describe those who might accept superficially sophisticated but fundamentally flawed ideas.

"This feels like the difference between science and engineering. Although to be fair to you, this paper really feels like somewhere on that spectrum and not fully on the side of science. It's similar to how every battery advancement doesn't always make it to manufacturing." - gusgus01
"Smaht[1] people have been trained to quickly and loudly dismiss perpetual motion machines, but also buy the whole 'revert carbon emissions' scam which is proven impossible by the exact same principles." - moralestapia
- "1: smaht. smart in appearance but actually dumb"

The Role of Economics and Incentives

Economic considerations, including the "time value of money" and the cost-effectiveness of solutions, are brought up. The idea that economic incentives might drive sequestration is contrasted with the simpler economic imperative to avoid burning fossil fuels in the first place.

"The underlying problem for all this is the time value of money/capital." - Terr_
"And if there was, any sequestration would just be used as an excuse to find ways to conduct more CO2 producing activities." - deadbabe
"Though I was thinking mainly of direct air capture. Point source is great, but not actually net sequestration. Need to look into this a bit more, but what would you say the theoretical efficiency is, could we reach a point where you can actually burn fossil fuel to net extract CO2 via direct air capture or another sequestration method that can be scaled?" - graeme