Industrial ammonia emits more CO2 than other chemical-making reactions (2019) | Hacker News Reader

Industrial ammonia emits more CO2 than other chemical-making reactions (2019)

cen.acs.org

121 pointsNoRagrets115 comments

Yes, this is the case due to the enormous scale of production. Replacing the hydrogen source at similar scales with electrolysis is plausible with base load power generation. The cost increase is a small integer factor, and in the bigger scheme of things is likely something we can adapt to at least for agriculture.

An obvious challenge is that we don't have available green base load power -- nuclear, hydro, or geothermal -- at anything remotely resembling the necessary scale. The requirement for base load power follows from the economics of industrial chemistry, which becomes much more expensive if you can't run your process in a continuous steady-state equilibrium. If we tried to produce ammonia via micro-batching chemistry or similar, those economics may not be practical.

The other unfortunate reality is that ammonia production is often a way to extract value from excess methane that might otherwise be vented or burned. It is a better use than the alternative. It isn't a coincidence that ammonia is primarily produced in countries with a persistent surplus of methane. As long as we have vast amounts of methane lying around, and we will for the foreseeable future, conversion into ammonia is a pretty reasonable choice since that carbon will often end up in the atmosphere regardless.

While nuclear has different pollution than fossil fuels, one can hardly call it green with the everlasting poison it produces.

At least the poison is very concentrated and easy to store. CO2 in the atmosphere is "forever" too, and much harder to deal with.

Not really, the most abundant life forms on earth consume CO2 to grow. Of course not at the rate we would like (especially with current coverage and that we’re still freeing more carbon daily by chopping down more forests).

They don't consume it, they store it temporarily.

https://en.wikipedia.org/wiki/Carbon_cycle

Green is an unhelpful umbrella term IMO. We need to be specific. Even "low carbon" is vague and prone to abuse.

Absolutely. But it is also helpful to for example subsidize low carbon energy, rather than solar and hydro specifically, because it allows for innovations outside of those specific options.

I was amused by other color coding for hydrogen, especially "turquoise hydrogen": hydrogen that is produced by pyrolysis of methane to hydrogen and carbon. This requires considerably less energy than conversion of water to hydrogen and oxygen. The carbon can then be buried so it doesn't oxidize.

The name comes from the combination of "green hydrogen" (electrolysis using non-fossil electricity) and "blue hydrogen" (methane reforming that avoids CO2 emission by capture and sequestration of the CO2).

With a proper breeder system we would not only significantly reduce amount of required Uranium mining (and thus its environmental impact), but also amount of produced waste and time at which it will be radioactively dangerous (from several hundred thousand years to several hundred). But, unfortunately, only the Russian government currently seriously invests into development of this area. Everyone else is fine with simply storing nuclear waste (with varying levels of finality and recycling), especially considering that it takes a minuscule amount of space as far as industrial processes go.

As far as I know - but please correct me if I'm wrong - the amount of waste is small enough that this is irrelevant. Additionally, having radioactive isotopes around is the natural state of affairs; after all, that's the input too.

Is the scale of the nuclear pollution really different from the scale of infrastructure-construction pollution for e.g. solar or wind? Because AFAIK either option is much, much cleaner than fossil fuel.

Finally, part of this teeth-gnashing seems to be centered on old fears. For instance, we have international treaties banning nuclear waste dumping in the ocean, but that's kind of absurd, considering that the amount is so low, and the ocean is so much larger than land, that water is quite good at absorbing and diluting residual radiation, and that any specific spot on the oceanic plate appears to be some of the least valuable ecosystem habitat on the planet. Why not just dump it in small containers somewhere in the middle of nowhere?

I believe valid concerns surrounding nuclear are primarily those of cost and delay. But this isn't some competition with e.g. wind and solar; it's a potential addition to replace e.g. coal, which is still a major power source all over the world. Comparing nuclear to solar is a distraction - if we manage to replace nuclear with e.g. solar+storage many decades down the line, that's great - but decarbonizing is extremely urgent, and we should therefore not be shutting down any routes to do so without extremely solid reasons.

> Replacing the hydrogen source at similar scales with electrolysis is plausible with base load power generation.

There is no need to tie this to base load power generation. In fact, quite the opposite: A lot of the electrolysis projects and the funding happening right now is targetted at using electrolysis as a compensation for fluctuating renewables.

This makes sense: We have cheap, green electricity, however having it in constant supply is expensive. So the smart thing is to shift the demand where that's possible.

This works because electrolysis equipment is cheap, so shutting it down half time barely increases total cost of ownership compared to the input electricity.

I don't think electrolysis equipment is particularly cheap, there's some excitement about cheaper alternatives coming to market and mass production that use cheaper materials.

But overall it's going to be the cheapest way to make hydrogen and then ammonia very soon. And the market has already seen that inevitable future, lots of right-wing Australian mining billionaires have jumped into the market hard for example.

The main saving is avoided carbon, which isn't priced in everywhere. But the sheer scale of ammonia production means it's easy to gradually introduce this as long as you spread the initial upfron cost across all the users (which is basically everyone).

It's a very mutually beneficial arrangement for renewables so the two things reinforce each other strongly and I think it'll be one of those things that moves faster than they expect.

The equipment is cheap relative to the cost of electricity to run it.

This analysis is 5 years old and it was already the case back then: https://www.sciencedirect.com/topics/engineering/hydrogen-pr...

I'm not sure exactly what you're referencing, as that seems a general topic you've linked to, but one of the articles I see at that link says that basically electrolizers are expensive enough that you need to be utilizing them at a high rate in order for it to make sense, and I think that's still true.

> In case of PtG applications, electrolyzer utilization becomes a key parameter. To illustrate the resulting utilization of electrolyzers when run on “surplus” electricity alone it is helpful to plot the residual load duration curves for different penetration levels of intermittent renewables.21Figure 11.4 depicts two typical residual load duration curves for a 30% and 80% share of generation from intermittent renewables of total electricity demand.

As I said, it’s an outdated analysis the point was theses things are a long way from 24/7 operations and have been for a long time.

“High electrolyzer utilization reduces the specific share of electrolyzer capital costs in hydrogen production costs; on the other hand, a higher utilization increases electricity costs, as hours of expensive electricity will increasingly be included. Hence, in order to minimize hydrogen costs, electrolyzer utilization has to be balanced with the electricity price.”

Of course the specific utilization percentage varies based on how expensive the equipment, it’s overall efficiency, and grid spot prices. We don’t actually know how expensive it is at scale so picking exact percentages is impossible.

Okay, there's a gap between requiring 24/7 usage, and "only exist for the purposes of using excess power that would otherwise go to waste" and I think we agree that electrolysis is somewhere in the middle of those two extremes.

If we are talking today then absolutely.

However, the grid is expected to have a lot of unused capacity. California is already at the point where 5% of all solar power produced is wasted and people are still constantly adding solar because the current economic break even is ~50% of all solar produced being wasted. That would average around 4-5 hours a day of basically “free” electricity which isn’t quite enough, but at scale at scale electrolysis equipment is almost that cheap and will probably hit that point.

This becomes more likely when you consider efficiency as a useful tradeoff. 40% efficiency at 2c/kWh or 20% efficiency at 1c/kWh potentially spend the same amount on electricity per kg of hydrogen but the second is likely much cheaper to build. You could potentially have several designs that get turned on or off depending on the current spot price.

Unfortunately that's not the case. Electrolyseurs are expensive (though hopes are they're gonna get cheaper quickly, as there's a lot of investment in this sector right now).

The economic balance of running an electrolyseur only part of the time is something to be worked out. Still the balance is almost certainly not "we need baseload".

The cost of electricity is already vastly more import than the cost of an electrolyzer at scale. https://www.semanticscholar.org/paper/Economics-of-convertin...

It’s to the point where even running 1/3 the time at the cost of 3x the equipment is likely a cost savings at scale assuming the local grid has a lot of wind/solar.

There is significant downstream cost associated with intermittent hydrogen production. Just because it is possible to produce hydrogen from irregular power sources does not imply that the downstream process chemistry can efficiently operate that way. As a rule, you want to run a continuous process for cost/waste reasons. Ammonia isn't craft beer. You really don't want to micro-batch a 100 million tons of industrial chemical production unless you are okay with being extremely wasteful of materials and energy.

You can solve the intermittency problem by building plant that acts as a hydrogen buffer to smooth out irregularities in hydrogen production. This substantially increases Capex/Opex that must be added to the cost of hydrogen that is already significantly more expensive than methane reformation. At some point, insisting that every step of the industrial chemistry process be done in a dis-economic way accumulates untenable product costs.

People need to be realistic about what is achievable at scale and the influence of economics.

Surely the hydrogen could be stored to allow for intermittent power supply? Make hydrogen when power is cheaper and there is spare.

Also, the continuous supply of power is exactly what the grid is designed to do. Availability of cheap nuclear or geothermal could change the economics. But the power is exactly the same if it comes from nuclear, renewables or battery storage.

With very-high-temperature reactors (one of potential paths for Generation IV reactors) you can produce hydrogen using reactor heat directly, bypassing the electricity conversion step, thus significantly improving efficiency of the process. And with sufficiently cheap hydrogen you would not be able to produce fertilizers, but also steel, another dominant CO2 source.

Oh I absolutely agree that nuclear is a brilliant choice for hydrogen production. And presumably it would allow nuclear to adjust electricity output whilst maintaining high utilisation and profitability.

But still I think there is a mistake in assuming that everything needs to be tightly coupled. The benefit of an electricity grid and storable fuels is that you have flexibility.

How is nuclear a brilliant choice for hydrogen production? Hydrogen provides inherent storage, so energy sources will (aside from cost of electrolysers) be competing based on levelized cost -- and levelized cost of new nuclear sucks. High temperature electrolysis doesn't change this: it reduces the electrical power needed by maybe 25%, at the cost of a nuclear reactor that has to operate at 1000 C with all the material problems that implies (there's a reason LWRs won and HTGC reactors did not.)

I don't have the expertise to answer that at a technical level. I think it could be a good choice because it would help balance out intermittent sources like wind and solar. And give alternative revenue streams for nuclear power.

If it balances out renewables, it also then pushes new nuclear entirely out of the picture.

I don't see why. Currently you would subsidise a nuclear power station because it provides reliable capacity that you may not need. The customer is created artificially by the market. But if you can link nuclear with hydrogen production the customer is not artificial anymore. You could provide guarantees about future hydrogen prices instead and still get the capacity. You then get a product that helps to decarbonise other parts of the economy.

It pushes out new nuclear because the levelized cost of new nuclear is much higher than the levelized cost of wind/solar. And with highly dispatchable demand, levelized cost is what matters.

Why should someone who wants hydrogen buy expensive nuclear electricity when they can use much cheaper renewable electricity?

Is then hydrogen liquefied? I remember reading somewhere that hydrogen requires pretty heavy/thick containers for storage. Does it need to be kept at low temperatures?

The Haber-Bosch process used in ammonia production is done at high temperatures (400-500 °C), so you can use "hot" hydrogen to power it (i.e. to heat input nitrogen) and maybe even extract some of leftover energy in produced ammonia heat to generate electricity. Same with steel production, you don't need to cool hydrogen before using it, on the contrary, high temperatures are useful in such cases.

Using "hot" hydrogen would mean that you have to build ammonia and steel plants right near nuclear reactors, which can be somewhat difficult, but potential efficiency benefits could be big enough to offset it.

HB consumes energy in its compressors, but releases that energy as heat on the catalyst. Hot hydrogen doesn't compress well, so you'd cool it beforehand.

For HB you need pressure of 250-350 bars, while existing PWRs routinely work with 150 bars of coolant pressure. I assume it's possible to produce hydrogen with the necessary pressure using VHTRs, i.e. you would get hydrogen already pressurized and hot. You would still need to run compressors on input water, but it's much easier than working with hydrogen later.

Producing hydrogen at pressure doesn't eliminate the energy needed, it just forces the electrolyser to act as the compressor (the voltage goes up).

Please, read the thread carefully. The point is that with VHTRs you don't need the usual electrolysis to split water into hydrogen and oxygen. Instead you can use high temperatures produced by a reactor to power conversion directly, thus improving the process efficiency. The most common option is the sulfur–iodine cycle. Granted, it's not so suitable for producing hot pressurized hydrogen (though it may be possible to separate iodine and hydrogen without condensation), but there are other options for thermochemical water splitting like high temperature electrolysis, which requires less electricity than electrolysis under STP.

Thermochemical cycles like that have been explored for decades and have gotten nowhere. For some wonderous reason, systems that involve vaporized high temperature sulfuric acid and the like have not proved to be practical. Falling cost of electrolysers and electrical power make that approach even more of a nonstarter.

If electrolysis can be made cheaper (E-TAC looks promising) you can run it at a reduced duty cycle on excess solar and wind power whenever they are available.

You can also produce hydrogen at the point of generation if water is available, and store it using the now obsolete natural gas distribution network.

People need to flip this excess electricity idea.

The cheapest power is solar and wind. If you build an ammonia plant, the cheapest way to get the power you need is to build solar and wind.

You can sell some excess to other grid users when you have too much, and you can stop production on very short timescales to help balance the grid during peaks but overall you'll be able to predict energy production years in advance and know upfront how much it'll cost you. Those financing benefits are a strong driver of the move away from fossil fuels.

This is already happening with actual plants, they build the renewables and the plant at the same time. It just makes sense.

So, green hydrogen will overall be a source of cheap 'excess' renewables power on the grid, not mopping up excess from other providers.

Green hydrogen becomes a source of more dispatchable excess power on the grid. This is more valuable than just randomly available power on the grid. Those renewables powering the ammonia plant can be diverted to sell to the grid when prices there are high.

Ammonia burns fine in a diesel engine with almost no modification, just swap the fuel pumps and injectors.

Let's make ammonia in Siberia to catch the methane from the melting tundra!

I for one am all for building green energy infrastructure at scale. However, at this point, I believe the push for green energy at the expense of nuclear, and even hydro projects at this point, has retarded the reduction of green house gases. It's a bit ironic that those wholly supporting wind/solar, have at the same time forced increased bureaucracy, and cost in other base load energy sources that could have helped in an overall reduction of emissions. So by fighting against climate change, they may have indeed made it worse.

Waiting for the Ammonia Shills to chime in that producing enormous amounts of ammonia that nobody actually needs will drive the development of green energy infrastructure.

Or, until we have enough excess electricity, we could replace methane steam reformation with pyrolysis.

https://en.wikipedia.org/wiki/Hydrogen_production#Methane_py...

The article points out that ammonia generates far more emissions than any other single chemical compound [1] but it is still a fraction of cement [2].

[1]: https://cen.acs.org/content/dam/cen/97/24/WEB/09724-industri...

[2]: https://www.nature.com/articles/d41586-021-02612-5

While roughly 3/4 of total emissions come from generating energy (electricity, heating, moving things).

https://www.wri.org/data/world-greenhouse-gas-emissions-2018

This is the well known Haber-Bosch process, "Between 75 and 90% of this ammonia goes toward making fertilizer, and about 50% of the world’s food production relies on ammonia fertilizer."

For those not looking to create a free account to login and view it:

https://webcache.googleusercontent.com/search?q=cache:-5f9t9...

It’s worth noting that the Haber process doesn’t require methane, methane is used as a source of hydrogen because it’s cheap and easy to use. Any source of hydrogen could work, but most of them are more energy intensive and thus more expensive or inefficient than just using methane. If you wanted to use nuclear or renewables, you just dedicate your energy production to electrolysis or whatever.

Edit to add: also worth noting that electrolysis currently amounts to about 5% of hydrogen production. You basically can’t remove fossil fuels from the food supply without lots of alternate energy input, so this is not a short term fix short of spooling up all kinds of nuclear reactors.

I’m not saying it shouldn’t be done, and maybe if we need to be dependent on fossil fuels for any one thing then we should prioritize food supply rather than literally burning them (or worse, venting them to the atmosphere as is often done with methane), just trying to set the right expectations for people who might be learning all this for the first time.

You can still use methane as your hydrogen source for ammonia production if you do CO2 capture and storage when you produce the hydrogen. This is often called blue hydrogen, as opposed to green hydrogen from electrolysis and gray hydrogen from methane witgout CO2 capture and storage.

Most of the oil and gas companies are partly betting the farm on H2 from CH4 with CO2 capture and storage as a major source of energy in the coming transition, and thus a major source of profits for the next 30-40 years.

Many people regard CO2 capture and storage as an attempt by the oil and gas industry to be able to green-wash what they current do without actually having to change anything.

I don't really care if Exxon is the most valuable company in the world because they discover a way to capture CO2 out of the air and pump it into old wells.

Almost everyone agrees (finally!) global warming is an existential threat for humankind. If you start bringing up other random environmental concerns you lose supporters quickly.

I agree it's easy to spin it that way. But I do also think it's true that we can scale up CO2 capture and storage one or two orders of magnitude more quickly than we can scale up renewables. And we will need that capability.

Just take solar power in Europe as an example. It is projected that we need to install 300 GW of solar in the next three years. But the rate of new installations has been basically flat at about 20-25 GW per year for the past 10 years.

Or take wind - we are going to install 21 GW this year, but next year that number will decrease due to constraints in permits and transmission grid capacity. To meet climate targets we need to add at least 30 GW per year.

At this point it's simple math that renewables cannot be deployed quickly enough.

You can also produce methane from renewable biomass (biogas), this is mature tech and in many places used as a transport or CHP fuel.

Define short term, if we really want I`m quite sure we can dramatically increase pv power generation in a few years. There are vast swathes of little used space in sunny environments. But you do need to invest proper amounts of money, just like we do for developing new fossil fuel sites. The investment for a new LNG field and liquefaction plant is in the order of USD 30-50B. We need to redirect such investments to PV and hydrolysis.

"cheap" in the same sense as free parking in cities, as in "someone else pays the cost". And the "someone else" in these cases is actually us a.k.a not cheap, but rather pointlessly wasteful.

This process is the reason Malthus was proven wrong back in the day. We wouldn't be able to support 8 billion people without it.

Given that

> Malthus observed that an increase in a nation's food production improved the well-being of the population, but the improvement was temporary because it led to population growth, which in turn restored the original per capita production level

What proved him wrong (or at least currently looks that way) was declining fertility levels, not increased food production.

Malthus was wrong because he assumed that people would always want to have a lot of kids.

Back in his days people would have a lot of kids because they kept dying, but he didn't realize that. Nobody did at the time.

This became very apparent when a chemicals company with plants in the UK annouced plans to curtail their ammonia production, and it was going to have a knock-on effect on other industries because they got a lot of their CO2 from that process: https://www.theguardian.com/environment/2021/sep/17/warnings...

B.S. Story. This happens every year. CO2 for drinks etc is always in short supply in the summer because it can only be made cheaply as a by product of ammonia production, which slows down in the summer due to no demand.

It’s largely 80/20 right - 80% of emissions come from a small group of sources. That’s hopeful, in some way, since it opens the door to big wins if we tackle those large sources first.

I wrote up a summary of the big picture emissions here last year: https://climate.davis-hansson.com/p/big-picture-2020/

You could make ammonia on wind or solar farms in the middle of nowhere and get it via tanker a couple of times per year, obviating the need for expensive powerlines. Bonus: the tankers can run on ammonia fuel.

I don't know about ammonia, but aluminium (a similarly "energy-intensive" commodity) is produced in Iceland where they have lots of cheap geothermal energy. Similar situation, making use of a local energy source and exporting the embodied energy as a physical product.

That's exactly what I read while traveling there, that this is why there's so many aluminum plants – because aluminium requires a lot of energy that they have for almost free, yet they cannot export (as electricity) due to their distance to potential markets.

Aluminum plants might require a bit more tending than ammonia, which can be made out of thin air and seawater...

This is very interesting from an agricultural perspective. According to the Wikipedia article for ammonia, “In the US as of 2019, approximately 88% of ammonia was used as fertilizers”.

To me this is a very interesting and damning fact with regards to current dominant agricultural practices. Yet another reason that it would be beneficial to further redevelop closed loop nutrient systems. For instance, sewage solids from cites in are sold to farmers for use as fertilizer.

Funnily enough Fritz Haber (who developed the Haber Process used to manufacture ammonia) also developed chemical weapons in WWI. Some people claim he is somewhat redeemed by his contribution to artificial fertilizer. I disagree with this reasoning on several levels.

Why is it damning that 88% of ammonia is used in fertilizer? Is their some other industry that ought to consume a larger percentage?

We could avoid this number by investing in soil preservation, nitrogen fixing plants, reduce meat consumption, even in concepts like humanure.

None of these would produce as much food per area and time. Reducing total calories required by eating less meat is a different argument.

Didn't said that we can substitute industrial ammonia but it could definitely reduce it's use. Changing the way we eat it's definitely an opportunity to reduce major sources of c02 emissions.

> For instance, sewage solids from cites in are sold to farmers for use as fertilizer.

Seattle tried shipping their shit (literally) to the farmers in Central Washington. Used these trucks that had "loop: turn your dirt around" splashed on the side. Then the farmers decided maybe they ought to test that stuff for PFOA/PFAS before applying it to their most valuable asset.

You don't see those trucks anymore.

A local "green" grocery went from selling hot food in plastic clamshells to using compostable cardboard. One guess what that cardboard is coated with to prevent liquids from soaking into it.

We abandoned "closed loop nutrient systems" long time ago for good reasons. Prion and hormonal pollution are comparable to radiation.

Also "Fritz" is very nacy name. And fertilisers can be used as bombs. Very very bad bad!

> For instance, sewage solids from cites in are sold to farmers for use as fertilizer.

If this was human waste wouldn't it have to be treated to remove chemicals viruses? Couldn't you get HEP-A from this process? Seems impractical and dangerous.

Biosolid fertilizers are widely used for decades in turfgrass. That’s not a claim that they’re risk-free, but rather just noting that it’s a well-established process.

Milorganite is probably the best-known nationally available brand you can buy in the home center near you, but some municipal treatment plants also sell locally to small/home users in addition to the more commercial scale usage (golf courses, etc)

I’m not sure of their level of use in feed grasses.

The story of Fritz Haber first wife is very sad https://en.wikipedia.org/wiki/Clara_Immerwahr

> For instance, sewage solids from cites in are sold to farmers for use as fertilizer.

That's how we get the next pandemic.

The energy use of agriculture is overstated. It's a rather minor part of the energy consumption of society overall. In the US we use more energy cooking food than we do growing it (which is about 1% of total energy use). (Note: this ignores the direct use of sunlight falling on fields growing crops.)

I wonder why you see his chemical weapons developments during WW1 as a particularly egregious sin.

My great grandfather was on the front lines in France and was gassed several times. To the day he died you could see the veins in his eyes from that experience, but when I went to the local VFW with him as a child and saw the men with no arms or no legs - the product of boring old TNT and shrapnel - I would always ask myself why we handwave that as the costs of war.

Collecting cat urine for ammonia production (as was done in the past) might make more sense these days, as the food cost would be offset by the near unlimited supply of cute cat videos - which could be detected with AI. The carbon emitted by respiration would probably be dwarfed by the emissions from users watching the videos, so more work is required on the efficiency of video playback before this could become a viable solution.

This process would be a good candidate for point source carbon capture and storage. Unfortunately CCS seems to have mostly been a red herring so far, but if it's going to work anywhere, this is a perfect application.

In processes which emit a lot of CO_2 - is it not possible to capture that CO_2 before it's just released to the outside atmosphere? i.e. when it is rather highly concentrated?

Why is depopulation not even a consideration as a solution for climate change?

Surely there are ethical ways to implement it.

Or do the world's largest and wealthiest nations only care for their hold on economic power?

Depopulation as in killing people? Or as in the one child policy?

It turns out you don't need to implement a one child policy: people implement it themselves when the cost of living gets high enough.

obviously not killing people.

I'm just demoralized that low birth rates are stigmatized as they are correlated with lower GDP, when low birth rates are somewhat of a godsend in times like these.

Then nations with low birth rates scramble to find ways to up the birth rates despite understanding the C02 cost.

It's ironic, really.

> low birth rates are stigmatized as they are correlated with lower GDP

You have this backwards

the case in point was obviously Japan which fell from the third largest economy to the sixth largest in the past two decades.

Japan wants to be like China and the US, not like Qatar or Switzerland.

GDP is not GDP/Capita

I believe you have this backwards.

the hard part about shrinking populations is that they cause your population to get older which has a bunch of annoying economic side effects (like fewer people working)

> I'm just demoralized that low birth rates are stigmatized as they are correlated with lower GDP

Low birth rates are correlated with higher GDP/capita; concerns are raised about them because they have a (decades delayed) effect of population aging producing a drop in the ratio of workers to those two old and infirm to work.

The real problem is "living behind your means" at a generational level by putting debt in future generations. This is a problem with democracy, which incentivises short term gains over longer term. The solution is democracies that aren't allowed to accumulate long term debt over agreed upon levels.

The problem is that politicians always choose to hide the true cost of living.

Because the damage will be done in 30 years. It's not possible to reduce population enough to matter in that time frame without mass genocide.

It's possible to reduce population by about 40% in 30 years without killing anyone, isn't it? Why is that obviously insignificant?

No that is not possible without killing anyone because people will fight for the right to reproduce. You can't stop babymaking completely without violence.

https://en.wikipedia.org/wiki/The_Screwfly_Solution

(An alien invasion story where there's no fighting back like in Independence Day)

How do you simultaneously convince a whole generation of people to not have children? To a significant percentage of people, wearing a mask during a pandemic is too much of an imposition on civil liberties.

First, 40% is nowhere near enough of a CO2 reduction, we need ~99.9% over slightly more than that timeframe; second, that’s a zero child worldwide policy, and doing that would require violence; and third, you have to ask who you’re doing this for if you’re not doing it for the next generation.

I am now curious what graph of age vs. CO2 emissions looks like for various populations…

I didn't mean it as a serious suggestion, just that it's technically possible to reduce the population that much without killing anyone.

Are you serious that to reduce CO2 "enough" world population would have to be under 8 million people?

When the Industrial Revolution started, mid 1700s, world population was something like 800 million, wasn't it?

Why would it be necessary to return to the world of 4000 BC, which is what I believe 8 million corresponds to?

Quality of life. We don’t want to live like we did in the 1700s — 95% of “rich” nations back then were subsistence farmers, and even the richest kings were in many ways worse off than minimum wage G7 citizens today.

This is also why I think the solution is to focus on the CO2 itself and not on the people. Green power, green sources for chemical feedstocks, are much faster and less violent than population limits; and also lower population doesn’t itself guarantee lower greenhouse gases because everyone might just use more.

I don't understand.

How would two more orders of magnitude reduction make things better?

We don't want to go back to the 1700s, so going back to the dawn of history is better?

What would North Korea be able to produce without 2/3rds of its population and without China?

He means, CO2 as a problem requires us to reduce our additions to the atmosphere by roughly 100%.

This is entirely possible, mostly by no longer burning fossil fuels, which is the prime contributer to the problem.

It is not practical or possible via population growth reduction, which has basically already happened (people live longer so there's a delay in the result being seen, but we've basically peaked already).

Unfortunately, it's politically tricky to stop burning fossil fuels, because people with financial interests in fossil fuels would prefer to destroy human civilization instead. And one of the many ways they do that is by encouraging people to believe that modern life is impossible without burning fossil fuels and so we should kill billions of poor people instead of just using cheap renewable power.

>roughly 100%.

I don't understand the use of "roughly" here. A reduction can be and often is, expressed as a ratio.

Is 90% roughly 100%? Is 99%? Is 99.9%?

As ratios, these are reductions of 10x, 100x, 1000x, and as ratios they can increase without limit. So what is roughly 100% and why is it necessary?

Given how long CO2 remains in the atmosphere, any reduction in CO2 emissions by less than 99.9% of the current emission rate sustained for less than a millennium is likely to result in severe negative consequences. Likewise, because the damage is done by the quantity in the air rather than the instantaneous rate of emissions and absorption — the former being the integral of the other two — we need to make these changes much faster than the gradual reduction over one human lifetime of non-reproduction.

If you want to achieve this reduction just by population reduction — and not via technology, lifestyle changes, or any other solution — then you need a 99.9% population reduction.

If you want to solve it by enforcing lifestyle changes and no tech etc., then you have to wind the clock back to before the industrial revolution, before we could even mine so much fossil fuels in the first place.

The 1750 population of 760 million [0] was (with regards to CO2) sustainable, but the tech back then limited both the population and the emissions.

It’s like the correlation between shark attacks and ice cream consumption: Hot weather makes you eat ice cream and go swimming. Icecream-to-Sharks isn’t directly causal, and neither was the population in 1750 the direct causal reason that CO2 emissions were sustainable.

So you only get the “benefit” of 1750s population levels if you’re willing to also pay the technological cost. But not just the cost of not being able to grow food for 8 billion: it would be as if the 710 million absolutely worst off today were unchanged, while the other 50 million merely don’t have electricity let alone computers or the internet, paved roads let alone cars or bicycles or public transport, disease-free pressurised municipal water let alone modern flushing toilets or bottled soda or warm and safe showers, etc.

Those 50 million would be the super-rich of the new era.

And worse, because of the aforementioned long lifespan of CO2 in the atmosphere, you’d need to sustain this for about a thousand years despite everyone involved being much better off if they defect (Nash equilibrium).

That leaves green tech. Many purely technological solutions to greenhouse gases are already known. The challenge is to make the green solutions cheaper (because Nash equilibrium) than the polluting status quo for 99.9% of effective emissions. (Effective emissions rather than gross emissions, because some of the technological solutions are to take CO2 out of the air to make other chemicals with, and that’s fine).

(ZeroGravitas interpreted me correctly, FWIW).

[0] I’m approximating from these numbers: https://en.wikipedia.org/wiki/Estimates_of_historical_world_...

>because the damage is done by the quantity in the air

Given this is true, then there's no particular reason to think that even 100% reduction of emissions would meet any goal.

I think you've just explained why carbon capture on a huge scale and carbon-free power might be necessary.

But if so, then I don't see "99.9%" as being connected to anything.

>So you only get the “benefit” of 1750s population levels if you’re willing to also pay the technological cost.

Here's a misunderstanding between us. I take for granted that "willing" isn't a factor, that 1/10th of the population would be unable to maintain current technology, that most, although not all, of technological advancement has come from increased population allowing more specialization.

>Those 50 million would be the super-rich of the new era.

It seems like something is missing in the previous paragraph, why do 50 million people have something different, and what is it?

> Given this is true, then there's no particular reason to think that even 100% reduction of emissions would meet any goal.

There is, but it’s been outside the scope of this discussion.

The exact reduction needed depends on what level of damage your are willing to accept, but 99.9% reduction relative to current emissions is basically the threshold for maintaining static CO2 levels until all the fossil fuels are burned. This still isn’t amazing at current CO2 levels, but as it’s the (approximate) steady-state emissions level, it remains a useful approximation of maximum safe emissions regardless of what the actual concentration is.

More emissions? The concentration drifts upwards from whatever is deemed to be acceptable when you started.

> Here's a misunderstanding between us. I take for granted that "willing" isn't a factor, that 1/10th of the population would be unable to maintain current technology, that most, although not all, of technological advancement has come from increased population allowing more specialization.

We definitely have a misunderstanding, because I’m afraid I don’t follow your argument, and I sense I’m not even aware of what conclusions you’re trying to reach with them.

I will attempt to respond nevertheless.

If we go back to the pre-industrial age, even if you get near perfect buy-in from everyone alive today, nobody is going to think it was a good idea in retrospect, and in 80 years everyone will ignore any pleas from the ancestors in the history books to never return to all we have now. We just go through a hybrid of the Industrial Revolution and the renaissance, which sounds like an awesome setting for a novel but not actually that good for the environment.

By the time the new societies have enough spare capacity to fix what we can already fix, let alone the stuff we can’t, CO2 levels will be much much worse.

> It seems like something is missing in the previous paragraph, why do 50 million people have something different, and what is it?

I was focusing on the negatives explicitly to show why it won’t be accepted by basically anyone if you try this. To focus instead on what the rich will have:

“What” the 50 million have is business, property, pets (rather than livestock), and some limited travel. Might even be able to dig up and reuse old plastic etc. from the before times, but (returning to the negative because I don’t think I’ve fully emphasised how much this will suck) even for the rich, many things trivial in our society simply can’t be newly made at all in the scenario you’re describing, as that is some combination of unacceptable (if you allow modern fossil fuel power stations, the pollution per person is too high, so no aluminium) or simply impossible without ending the scenario (can’t develop a vaccine for a novel virus on a supercomputer because the world economy can’t afford to build the machines that build the machines that build the parts for the supercomputer, but even if it could, the tantalum mine needed for one specific component is both closed and probably in a different continent which is now only accessible by wooden boats and you don’t have any advance warning of Atlantic hurricanes forming).

The “why” is that this was what happened in every historical society of this type that I’m aware of. The rich 50 million is everyone who isn’t literally (in the medieval feudalism sense of the word) a peasant — not a very high bar by modern standards, but not passable without tech that one way or another breaks the scenario.

System will find balance. Price will increase. Fertility will decrease. Surely it won’t be easy way, but system doesn’t care about easy way.

no it isn't. that would require no one having children for the next 30 years which you know, can't happen. realistically, the maximum amount of population reduction possible without genocide is somewhere around 2% per decade. otherwise you are going to run into insurmountable problems due to effects is population agree distribution.

Depopulation is too slow to matter. We need to be carbon neutral in less than one generation. Unless you propose to start a campaign to kill billions of people in the next couple of years, you don't solve the problem.

Soylent Green (https://www.imdb.com/title/tt0070723/)

"In 2022, Earth is overpopulated and totally polluted; the natural resources have been exhausted and the nourishment of the population is provided by Soylent Industries, a company that makes a food [...]"

> Why is depopulation not even a consideration as a solution for climate change?

[...]

> Or do the world's largest and wealthiest nations only care for their hold on economic power?

It would be very easy for depopulation to be suggested as a solution for climate change without adversely impacting the wealthiest nations (well, I mean, if it was implemented as suggested—actually suggesting it might provoke damaging blowback.)

There are ethical ways to implement it for instance give more education to women [1]. Consuming less meat should be a priority for us wealthy countries. Overpopulation is a problem but carbon inequality is much worse [2]:

" . The richest 10% of the world’s population (c.630 million people) were responsible for 52% of the cumulative carbon emissions – depleting the global carbon budget by nearly a third (31%) in those 25 years alone (see Figure 1); • The poorest 50% (c.3.1 billion people) were responsible for just 7% of cumulative emissions, and used just 4% of the available carbon budget (see Figure 1); • The richest 1% (c.63 million people) alone were responsible for 15% of cumulative emissions, and 9% of the carbon budget – twice as much as the poorest half of the world’s population (see Figure 1); • The richest 5% (c.315 million people) were responsible for over a third (37%) of the total growth in emissions (see Figure 2), while the total growth in emissions of the richest 1% was three times that of the poorest 50% "

[1] https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3073853/ [2] https://oxfamilibrary.openrepository.com/bitstream/handle/10...

The problem is that there usually follows the question of who should have less children. And often the poor are seen as the problem, even though it's us rich people that emit more than we should. Famous people that are saying that the population is too high are Bill Gates or Paul Watson of Sea Shepherd, which both have 3 children.

There are some very nazi problems with the whole approach.

Covid could do that. But, somehow, people got so afraid on being in the depopulated side that the whole life become fuzzy nowadays. /S

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