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Comment by casenmgreen | Hacker News Reader

I may be completely wrong, but I have read that the underlying chemistry is endothermic, which is to say, requires energy to occur.

In other words, you have to generate energy to remove CO2 from the air.

Problem is, how do you generate that energy - on the civilizational scale required - in a way which produces less CO2 than you're removing from the air?

Right now we're already failing, globally, to replace dirty energy with clean. India IIRC has an aspirational goal to be off coal by 2070...!

How do we manage to produce a purely green civilizational-level energy supply, doing it all a second time over as well, and now or soon, to start producing the energy to remove CO2 from the air on a scale which will matter?

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You don't need to build carbon capture plants near people, you can build them anywhere in the world.

So you can put them in places where you have the potential for large amounts of cheap renewable energy that would otherwise be unused. Build solar plants in the middle of the desert, build tidal and wind generation on remote islands. There are plenty of places where green energy projects never got off the ground simply because the cost of transmitting it to places with energy demand was cost prohibitive.

The bigger problem is that simply removing CO2 from the atmosphere is not enough, you have to actually store it somewhere and be confident it will stay locked up for centuries, otherwise the effort is wasted.

You need to build carbon capture at emission sites however. Carbon density in regular air is too low for capture to be efficient, it needs to be captured as the air exits fossil fuel power plants, which is difficult enough as is (I believe we can reasonably get about two thirds of the CO2 this way) to not be enough at all. All in all, carbon capture is just a way to pretend to solve issues while only dealing with symptoms. GHG (and CO2) are just one of the many consequences of the excessive pressure our society has on our environment, and solving just one consequence won't save us from all the other (resource exhaustion, biodiversity collapse, GHG besides CO2).

It would have to be nuclear, I imagine. Doesn't seem like any other method would have the juice required while simultaneously being able to power all the other stuff we want (and not also creating emissions).

I can't believe the cosmic irony that probably the biggest "success" of the environmental movement and arguably its motivating raison d'etre might be the one thing that would destroy the earth's environment. Imagine an alternate reality where nuclear uptake continued at rates of 50s/60s and where we'd be today.

History has shown various times[1] that our timeline is the one to bet on when it comes to narrowly avoiding the extinction of much of human life. My bet is thus that one or several of the many ideas how to avoid a total climate crisis will prevail, in a soft-quantum-immortality kinda way.

[1] examples: Hitler‘s halt before Dunkirk and his various other silly mistakes (resulting in them not being able to develop the bomb first), Vasili Arkhipov‘s abort to launch a nuclear torpedo during Cuban Crisis, Stanislav Petrov not reporting what their systems indicated to be a nuclear attack…

Yeah let's just keep calm and carry on and hope that something magically saves us. That's probably going to work out great

Well, better to panic and run in 1000 directions, none of which going away from the planet that is so far our only habitat? It will work out one way or another. And either many-worlds is true, and some of them will carry on human life, or it’s not, I‘m wrong and all these examples were just lucky accidents. In the second option we‘re likely screwed either way, because the number of ways that humanity can kill itself is growing by the decade, and one of these will trigger sooner or later.

This is such a... strange way to essential just ignore the problem and hope it goes away. Like a student deciding not to study, because why would that help. Either he fails or another in a—essentially—another world does or doesn't. Problem solved.

This kind of attitude is problematic regardless of the topic though. Because whether it works out or not isn't dependent on you, because what you're describing is just noping out of the situation and ignoring it.

And, for those who genuinely do care, one way or the other. That take the many hours upon hours to write out good whitepapers on the topic, how is that panicking exactly? Sure, there is a lot of horror media, purposefully misleading information, and doomer attitudes thrown around from either side of the argument, and some of those average (statistically speaking) folk can probably be described as panicking. And there's also companies doing and implementing things only for the PR, or to remove heat from themselves, or preemt such things, and what have you. But I still wouldn't go so far as to write the entire topic off because some people are panicky and a lot of companies have financial incentives to earn more regardless of morality.

I do agree that, on the current course, I can't see humanity lasting very long, so to speak... that is, if nothing is done about it. Sure, perhaps nothing will work out. Perhaps everything will fix itself if one ignores the problem. Perhaps the fictional student ends up passing either way. Perhaps it won't. But is that reason enough to simply brush our hands of it? To just let it happen? Sitting back and doing nothing won't make things better either. Doing something has—at least—the potential for change, whether good or bad.

I never said to do nothing. I just don’t see value in worrying about things out of our control. I do my best to keep my family’s footprint low (and already live on a country with comparatively low footprint). But most of this whole thing is at best in the hands of corrupt politicians and at worst completely rudderless.

Survivor bias.

Well it is. The question is what percentage you assign to the probability of having survived so far. Depending on that it can give evidence towards many-worlds (coupled with the anthropic principle).

No so probabilistic, but more like a linear combination of approaches maximizing for gain function and economy of scale. I can tell you with certainty planting trees is far down on the list.

At the top of the list would be strategies that utilize biological processes as the capture component of CCS. Kelp and phytoplankton robotic oceanic aquaculture seem the most obvious. Going GMO to increase yield and reduce needs for micronutrients would probably be helpful. Terrestrial CCS would look like either chemical processes or DACCS. I think the Microsoft approach has legs to it if it can be demonstrated, Omniprocessor-style.

For soil health and to combat desertification, it would be wiser to stop rain forest loss and reintroduce megafauna across the world to improve non-wooden plains / semi-wooded land.

I think along the same lines. On the point of megafauna, isn’t it rather dependent on having enough large predators? E.g. in temperate forests, wolves have been shown to be very effective at repairing forest health by keeping deer at bay, leading to positive changes throughout the ecosystem.

The idea that Nazi Germany invading Britain would result in the extinction of most human life is utterly absurd.

Even a full nuclear exchange at the height of the cold war wouldn't have bumped off human civilization.

> History has shown various times that our timeline is the one to bet on when it comes to narrowly avoiding the extinction of much of human life.

I'm not convinced by that logic, although as I've never yet died, maybe I could convince myself that I'm immortal by employing it.

Using nuclear to power carbon capture will only make it more expensive. You do realize that only the cheapest energy is viable for carbon capture?

Also, among "pro nuclear" advocates there is this tendency to blame the problem on "stupid people" (environmentalists, politicians, Chernobyl watchers, etc) but once you disregard that and let them build their project suddenly you get budget overruns, delayed schedules and failed projects and surprise cleanup costs from decommissioning.

There isn't a cosmic irony. People are against nuclear power because frankly: it sucks.

> budget overruns, delayed schedules and failed projects

How the fk is that unique to nuclear powerplants? Also, did you take into account the same shit for coal plants as well, that are multiple orders more numerous?

I think people who are exasperated with blind nuclear activism also don't want coal. Yours is a strange kind of whataboutism that isn't even relevant.

Issues with commissioning/decommissioning nuclear plants are unique in the magnitudes of sunk costs, both time and money, as well as the somehow still astonishing to many delays and hidden costs that somehow always catch us off guard and somehow are unique to each site and were somehow completely unpredictable that nonetheless somehow happen in every instance.

Yet look at French’s energy graphs vs that of Germany.

Also, frankly, this is such a topic that the capitalist view makes no sense - there is no buyer/seller for green-ness (though it can be introduced into the system through laws like carbon taxes), these are costs that must be coughed up by governments, period.

I still believe that a nuclear baseline and a renewable variable energy production on top is the cleanest, greenest solution that actually further our case. There is simply no competition on the efficiency of nuclear.

Nuclear powerplants are far more complex and expensive than other plants, and thus there's a lot more things to go wrong.

And they produce orders of magnitude more energy than a similarly sized other plant, so the question is more like -- is a single nuclear plant statistically more likely to go wrong vs any one of 100 or 1000 "normal" plants?

Are we discussing the building of them or operation of them?

Due to the complexity of nuclear plants, any issues encountered during building are likely to drastically effect the costs and time required, whereas coal plants are a more mature technology that we already have a lot of experience with. NB. I'm not claiming that coal plants are a better choice (they're not), but that there's less risks involved with the financing and manufacture of them.

If we're discussing the operation of already built plants, then I can't find any stats, though I'm sure there's been at least some explosions or fires in coal plants. I daresay that a coal plant explosion is a lot easier to deal with and resolve than a nuclear plant explosion considering the problems with toxic materials.

But nuclear plants can’t explode, that’s just nonsense. There are 436 nuclear plants active on Earth and there was only two accidents in more than half a century, one with the older tech we already knew back than that it is bad design plus.. the whole soviet management of it, the other is a neverbeforeseen sized tsunami plus mismanagement.

> But nuclear plants can’t explode, that’s just nonsense.

I doubt your understanding of the phrase "can't explode".

> There are 436 nuclear plants active on Earth and there was only two accidents in more than half a century,

There have been more than two core meltdown incidents. Have a look at https://en.wikipedia.org/wiki/Nuclear_meltdown#Core_damage_e...

> but once you disregard that and let them build their project suddenly you get budget overruns, delayed schedules and failed projects and surprise cleanup costs from decommissioning.

Those idiots are NEVER disregarded, they've put in place a huge amount of extremely expensive regulation that makes nuclear 10x as expensive as it would be otherwise (compare 1980 nuclear power cost per KW to today), all to prevent the occasional Fukishima which kills one person and makes a couple of square miles uninhabitable (technically theres another 200 you evacuate from for a few weeks and then another 20 for a decade or so but a brief look at Fukishima radiation maps[1] shows nothing that would be over the cancer detection threshold[2]).

[2] https://xkcd.com/radiation/

[1] https://jciv.iidj.net/map/

> Problem is, how do you generate that energy - on the civilizational scale required - in a way which produces less CO2 than you're removing from the air?

The answer is simple: trees, moors and other biological processes. That would also work out on scale, as it has before humans have ever entered the play.

Forests and such are carbon neutral unless somebody goes there, cuts the trees, and crucially does something to prevent the wood from burning or decomposing for hundreds or thousands of years. That is the costly part.

That's a fairly simplified view of what a forest is. A forest is not just a bunch of trees, but an ecosystem where perhaps the most important part is the soil, which in the long term is the bigger carbon reservoir.

A lot of the carbon that first goes into the trees eventually ends up in the soil, which if left undisturbed (i.e. not used for farming) is stable and does not leech significant amounts of CO2.

Admittedly the downside of this is that such soil is almost absurdly fertile. This is in large why slash-and-burns are so popular where ever there's old forest. Indonesia, Brazil, etc. Like it's not even about the lumber, the farmland is amazing for a decade or so.

> A lot of the carbon that first goes into the trees eventually ends up in the soil, which if left undisturbed (i.e. not used for farming) is stable

Stable, as in the amount of carbon that is captured is offset by the amount that is released?

That sounds like after a short while forests become carbon neutral, unless we cut the trees down and do something to prevent the wood from burning or decomposing.

I think we are in agreement?

There's a lot more biomass in an older forest than a younger one, especially a planted forest. Carbon capture will slow down, granted, but a forest takes hundreds if not thousands of years to reach true equilibrium.

There's an immediately obvious difference in biosphere density if you step into a forest that was cut and re-planted a fifty years ago, one that was slash-and-burned a hundred years ago, and primeval forest that's been around since the end of the ice age. There's just a lot more stuff growing in a forest the older it gets. Trees keep growing for a very long time as well, easily doubling or even quadrupling the biomass of a younger tree.

All the fossil-sourced carbon we've put into the air the last 100 years or so was, at one point or another put into the ground, mostly by vegetation.

Re-planting forest isn't probably in its own an adequate solution, but it shouldn't be dismissed entirely. Compared to active carbon sequestration, the energy cost of letting a forest grow is negligibly low.

> All the fossil-sourced carbon we've put into the air the last 100 years or so was, at one point or another put into the ground, mostly by vegetation.

As I understand it, carbon comes from plant matter indeed, back from the Carboniferous period. Back then no life form had evolved that was able to break down wood lignin, so wood could not decompose. That stopped around 300 million years ago when certain fungi evolved, which is why carbon is no longer produced and thus remains a fossil fuel.

Forests are essentially carbon neutral according to every source I can find. I'll be happy to learn otherwise.

Forests are carbon storage. They sorta become carbon neutral over time, but they generally won’t burn by themselves in many kinds of climates.

Unless you are talking about terra preta (where you intentionally produce charcoal and work it into the soil), the natural process of accumulating soil organic matter is too slow to make a dent to climate change.

I've heard people mentioning biochar and similar processes of capturing carbon in the soil, do you know how viable it is? How much bang for the buck we could get from it? Is it a possible strategy when done in a decentralized manner all over the planet?

Except it tooks millions of years to capture the amount of carbon we are releasing in decades, and much of that capture will not actually work in today's ecosystems: all coal deposits were formed in the window of time between trees evolving the production of lignine and microbes evolving the ability to decompose it.

It takes ~40 trees to capture one ton per year, with ~40B tons emitted each year, that means planting roughly 160B trees each year. Humans have changed the world in a manner which natural ecosystems cannot recover on their own. We need to cut emissions to 0 and plant trees, establish moors, and other forms of CO2 capture.

> It takes ~40 trees to capture one ton per year

I'm confused, where is this CO2 going? Once the forest reaches its maximum average tree size doesn't it stop carbon capturing and just occupies space?

Yes, but I you cut and store the wood at maturity you could plant fresh trees instead. The point is, trees are an entirely inadequate solution to climate change, at least on the CO2 front.

How you going to store the huge amount of trees without decay (which causes emissions)?

How are you preventing soil depletion given you're cutting down and storing trees? Fertilizer production is very greenhouse gas intensive.

That's far too inefficient to supply the energy needed to sustain modern area-efficient farming, so which 5 billion people are you picking to die of starvation?

If I got the article right, the plan is to use underground carbon stores like a battery, “charging” it by pushing carbon under that has been pulled from the air, and “discharging” by pulling it up later? That has to be one of the most inefficient ways of storing energy imaginable.

Sahara solar plants + carbon capture? Solar capture in Africa is supposed to have a lot of potential except for the problem of transporting the power. If you can use it locally, maybe it's more valuable.

It's not clear to me if direct carbon capture needs to be distributed.

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