Hacker News Reader

Comment by colechristensen | Hacker News Reader

This analysis seems to skip the obvious step whereby the manufacture of cement involves expelling CO2 from limestone so that it can be mixed with water which re-forms the same compound by absorbing CO2.

Making Lime CaCO3 (+ heat) → CaO + CO2

Making concrete CaO + CO2 (in water, from air) → CaCO3

[there are lots of other things in concrete, but the CaO/CaCO3 are the media that glue them together into the useful composite they are]

They quote that as "half" the emissions, well those emissions are all reabsorbed by the product itself. The complete reabsorption does have a long tail, but if you expose CaO to air it will absorb CO2 all by itself.

The rest can be pretty trivially converted to renewable sources so it seems like this is just a big pile of scaremongering nonsense.

Which is unfortunate, it is difficult being scientifically literate and progressive being surrounded by people "on your side" who are spouting the exact same kind of nonsense and lies as your opposition.

View on HN

I think its worth considering how long that long tail is:

https://www.cement.org/for-concrete-books-learning/concrete-...

Taking at a look at the link above (which is published by pretty much the more pro-cement group you can imagine), we get that carbon resorption is a thing, that certainly there is a potential for many structures to achieve carbon neutrality over their design lifespans, and that in the "best case", we're talking about 100% carbon neutrality over decades. We also get that 100% carbon resorption is not a design goal of many forms of current reinforced concrete applications since the presence CaC03 increases rebar corrosion.

Taken at face value then, what you have is that cement currently emits 8% of all human carbon activity, that over the timespan of decades, it may self sequester itself to 4%, but probably somewhere in between. So even if we trivially converted kiln sources to renewables, there's still probably a decent chunk of carbon emitted in cement creation process that may never be self-sequestered.

I think understanding what that final number comes out to would be pretty useful thing to understand, and is hardly scare-mongering.

I think once we drill into our heads that we need to decarbonize, after "the easy step" of cutting fossil fuel use, litterally every other form of decarbonization consists of chasing down some carbon source that accounts for the 2-5% range. There will be no low hanging fruit left.

https://link.springer.com/article/10.1007/s41024-016-0010-9 is a pretty nice discussion of concrete carbonation as well.

It is also worth pointing out that the GP's comment was showing the chemistry for a lime-based concrete. OPC (Ordinary Portland Cement) based concrete is substantially different in terms of the chemistry and the amount of energy involved in the manufacturing process (due to the increased amount of energy involved in producing the clinker).

I'm not very worried about the remaining carbon producers once fossil fuels become minority energy sources.

I think the ability of the biosphere to sink carbon is underestimated as are the benefits of a higher carbon atmosphere. Most talk about anthropogenic climate change are either denying it exists or exaggerating (usually without much knowledge) its negative side effects. Nobody talks about the benefits of expanding the arable land at higher latitudes or increased plant growths in forest (and forests denser and further north). At one point during a carbon spike the planet was more or less covered by jungle pole to pole, how's that for biodiversity? Change is hard and people are always upset about it, but this is a change we have already made for better or worse. There is much doom and gloom about any change and this one will have big consequences but we need to move past arguing about whether or not it will happen and towards how best to respond to it (and in ways other than only desperate attempts to reverse it completely). That doesn't mean there isn't a great benefit to capping the size of the change or to stop the forcing, but at some point you have to accept it and stop treating it as your doom.

Ok, thats a fair position to have.

For what its worth, I also wonder about that. I live in Canada, and I'm not aware of what steps are being taken to understand how we would have to respond to growing areas moving north. I've read that the areas where favourable climatic conditions are projected to settle in that we only have sufficient top soil for a few decades of intensive agriculture. I wonder what steps are being taken to deal with that.

I also would point out that people are upset that change is happening because they look at the form the change is projected to take, and most of the forms of change involve a lot of people either dying, or just having shitty shitty lives.

Agriculture has learned a lot about topsoil. Farmers are actually growing topsoil now. Most history books stop covering farming with the 1930s dust bowl. Thus few people are aware of what universities have discovered since.

On the question of whether a warmer planet is inherently bad for humans, ignoring adaptation costs (which are large), I’d note that the richest countries tend also to be the coldest ones. Coincidence? Hard to say. But I’d rather not bet the future of civilization on getting the answer wrong.

That is interesting, I wonder if it is possible to pull apart the factors. I always thought it was a combination of the long shadow of colonialism and things like malaria.

I‘m worried that as the earth is warming up the benefactors of it become so powerful that they start to defend the new status quo. Say the main benefactor would be Russia, and Canada‘s population would grow to 300 million and take on the US‘s role as a global superpower. It would be very hard to convince them to go back to where we are now in supernational bodies, and consensus would be impossible to achieve.

Meanwhile we have to say good-bye to New York, Shanghai, the Netherlands, and many other places that are close to the seas.

Large parts of The Netherlands are already below sea level. We will be fine.

I'd be more worried about invasion from armies than the sea. There's a strange assumption that the losers in climate change will just sit calmly and accept their fate.

Armies? From where?

From countries suffering social unrest caused by climate change, electing populist leaders proposing to solve the crisis in their borders by expanding their "living space" and so on.

History is a circle...

No, History is not a circle, it never repeats itself because the variables always change. Context matters.

> proposing to solve the crisis in their borders by expanding their "living space"

When you are in a crisis mode you don't have to time to wait for elections, the most likely result of social unrest is civil war. There are ample examples in very recent History.

From places with hungry people and newly-arid landscapes. What do you think will happen when they can't get visas? Just happily sit there and starve?

I have a hard time picturing how tired and hungry people would suddenly become a threat against countries producing all the weapons in the world and armed to the teeth. But surely you can explain?

China, as noted by others, stands to lose a lot of arable land and makes plenty of weaponry. India and Pakistan are both likely to become more or less uninhabitable, and have nukes and (for the former) no shortage of people to draft. The United States of America, under a 4C rise, would also see large regions become uninhabitable, and has a northerly neighbour that could not repel an invasion. Russia has already shown a fondness for acquiring territory (see Crimea) when the opportunity presents itself, and Europe is weakly defended.

Not to mention that "set up turrets on the southern border and mow them down" is not the most humane way to handle this, especially since the nations likely to fare OK(ish) are generally the ones that caused this trouble in the first place.

OK, maybe central Africa is not going to be a major military threat.

How about China and India, whose southern parts are densely populated, and who are capable of launching rockets to space, have nuclear weapons for a long time, etc?

You don't want them to feel desperate.

China and India are not desperate enough to choose to reduce their projected increase in coal-fired power stations. Nuke themselves?

No, the idea is:

1) Keep building coal stations

2) Invade northerly regions that are now better for growing crops

Not just China and India. Russia could just about do this for the lolz when you consider they're already expansionist.

Mind you I'm not _endorsing_ this, I'm just worried about it.

> Russia could just about do this for the lolz when you consider they're already expansionist.

In all seriousness if you really want to picture Russia as expansionist, the only time when this was really true was post-WW2 and Cold-war Era. Now Russia is far from being a fool enough to "invade" countries around much beyond their border. Let's not forget NATO as well. I'm not sure in what world this scenario would ever happen.

We already have 'open borders'.

Dude, you're being very un-dude.

Also, it might be a good idea to bring evidence of this forward since immigrating seems to be getting harder as time goes on.

Schengen is literally an open border treaty. Zhe Germans could invade The Netherlands by driving about a thousand cars and trucks in smeared over a couple of days.

Then change to combat dress and take over.

How is that not an 'open border'? No need to bomb Rotterdam.

True, but so is the border between Flanders and Wallonia. The Schengen border itself is the relevant one there.

My original comment was about NL. What is your point?

Trying to control nature will never work out in humanity's favor. That is precisely the same hubris that has landed us in this mess. Once we surrender to the notion that we will capitalize on nature's response to our unwieldly use of technology, then we are only going to make matters worse. We simply do not understand the complexity of nature and should be skeptical of perceived benefits -- such as increased amounts of arable land -- as if that won't have consequences.

Never? An enormous part of civilization is exactly wrestling for control of nature and succeeding. From prairie nomads to mega-cities our direction is clearly one of increasing control. The whole issue is about humans changing the climate. We already have incredible control of many complex systems, the planet's climate is just another system.

It will take an incredible amount of resources to control but there should be no doubt as to if, only when. The earth is our garden, we have only to put ourselves to the task to make it bloom. The blocking point is our intentions and efforts not the possibility. You can't be burning down the Amazon for a quick dollar and trying to maintain the climate at the same time. We're so focused on arguing about whether or not we're having an effect and panicking about what that will be that we're not really trying at all to gain any control.

True the climate is not a trained dog, it will not act on command, it is not a linear system that we can put one PID controller on and be done with it. It is complex, it has feedback system on top of feedback system, some negative, some positive, it's chaotic. None of that means we can't make it do what we want.

We just have to focus and not spend our time on the stupidity that drives our everyday political process.

The problem of taking control over complex systems the size of climate isn't about knowledge or technology; it's a coordination problem. We could be having climate jumping through hoops on command today, if we could coordinate at global scale instead of competing and sacrificing long-term benefits for next quarter rewards.

Humanity has controlled nature for thousands of years. We have achieved unthinkable progress in almost any thinkable area.

I mean, I get your point: It's hard to control complex systems, and unintended consequences can and do happen.

But we have a rather spectacular track record of powering through and figuring things out.

The way I understand it is that we just don't want an erratic climate with lots of mood swings.

By the way, on the topic of a changing climate and especially when climate at x changes to y, y changes to z, changes to etc; that is what some of my research is about in the context of agriculture.

Edit: Somewhat obviously, we also don't want to lose current biodiversity.

Very interesting this reminds me of motorcycle riding in the cold and I think you are right. It is very hard to keep warm so you wear warm pants and a jacket and that helps but it can still be cold. It is all about percentages. Add nice boots and you may be 1% warmer. So add a scarf tbat gets you anothe %. Gloves another 2%. All the little things alone don't do much. But once you start adding them up the little pieces add up fast and make the final and most important contribution to the problem. Like you mentioned it will be all the little areas of carbon emissions we will be tackling which will ultimately need to be the hardest and most important step.

Very reminiscent of many conversations at work.

“And then the hard work begins...”

Optimizing the long tail is a slog. But when it’s most of the remainder it has to be done.

That's also why it's so important to get the easy 80% of the work done as quickly as possible.

The longer we get to sort out the long tail the better. The more time we have the higher the chance of creating efficient CO2 scrubbers, then we can cut a lot of the tail off..

The reason why is you are wrong.

Portland cement, when hardened, does not absorb any significant amount of CO2. It does not form limestone. It mostly forms CSH [0] which just takes water, silicon dioxide, and quicklime. The last is sourced from limestone but does not turn back into limestone.

[0] https://en.wikipedia.org/wiki/Calcium_silicate_hydrate

Across the world, what percentage is Portland cement vs the other CO2 absorbing kind? I googled around, but couldn't find the answer.

Nearly all, much to the frustration of heritage building owners everywhere. I just spent a few weeks manually chiselling off a godawful cement render from a wall to restore a naturally-hydraulic-lime based one. The cement crap is rock-hard and doesn't have any moisture permeability, so water gets in and just dissolves your building (or more importantly, the old lime-based mortar holding up the dozens of tonnes of stone that is your home)

Per TFA, 98% of concrete is made from Portland cement.

And basically all the other forms of cement in use starting with the Romans.

https://rootsofprogress.org/cement-redux

Do you have any references on the actual speed of reabsorption? I tried to find some, but didn't have much luck. I've heard numbers as high as 200 years to absorb all of it, but I don't know how "all" was defined for that metric. 90%, 99%, 99.99%? The actual rate of reabsorption is a pretty critical metric here. Even if it only takes 50 or 100 years to absorb half of it, that may not be fast enough as CO2 levels in the next 50 years are still pretty important considering potential feedback loops that could be triggered in that time frame.

The implication "manufacturing cement is a significant contributor to man-made CO2" might be imprecise if most of it were reabsorbed in the final produce. However, I don't see any argument why we should not be trying to absorb this CO2 - sure, concrete could aim to be carbon neutral, but why shouldn't we aim higher?

> The rest can be pretty trivially converted to renewable sources

Your other claim is, as others have pointed out, wrong. But also calling the renewable use in high energy industry "trivial" is quite a stretch. Here's a recent article on the issue that gives you an idea how challenging this is: https://www.vox.com/energy-and-environment/2019/10/10/209042...

> Which is unfortunate, it is difficult being scientifically literate and progressive being surrounded by people "on your side" who are spouting the exact same kind of nonsense and lies as your opposition.

Tell me about it. I once talked to someone who says it's good that people are scaremongering on global warming because otherwise nothing might get done. They say there's no such thing as bad press, but I think it does science a disservice in the long term if perception is that it fails to deliver.

Press is often not even wrong about climate, and isn't even scaremongering properly. I'd say that accurate scaremongering involves mentioning things like "mass migrations", "loss of habitable land" and "opening up resource-rich areas", which cause things like "humanitarian crisis", "war", "mass starvation" and "collapse of technological civilization". I'd like to see press that dares to mention that.

We don't have decades to wait for building stocks to re-absorb the expelled CO2.

(Setting aside concrete carbonation, there are better materials to use for building construction. Concrete is a poor insulator, and sourcing other materials will reduce secondary and tertiary energy consumption. Also, buildings can generate energy, but not if they are made of concrete.)

I understand that you want to rationalize concrete use via carbonation, but consider the bigger picture. There is simply not a sustainable future in which we continue to build everything with concrete. Perhaps if decision-makers of yesteryear had considered these scientific properties (along with climate change), this could have been included in a comprehensive strategy to limit GHG emissions, but we are well beyond that point and must eliminate CO2 emissions now.

We already have lots and lots of building stock carbonating right now.

But yes, building has accelerated, so we are not in a steady state.

As an interesting aside, tossing lime into the oceans might help. Ignoring the energy costs, once inside the ocean the lime apparently binds twice as much carbon as was released when making it.

That process also helps against ocean acidification.

So in order for the whole thing to make carbon sense, you'd need to use stranded energy that wouldn't be used for anything else and doesn't release more carbon into the atmosphere, like solar power in a remote desert. And the balance gets even better, if you manage to capture the carbon release by the quicklime making process.

See https://en.wikipedia.org/wiki/Enhanced_weathering and https://en.wikipedia.org/wiki/Iron_fertilization

Here's a relevant article from the publication Nature: "Substantial global carbon uptake by cement carbonation" https://www.nature.com/articles/ngeo2840

Coverage of Nature letter in the popular press: Concrete products reabsorb nearly half CO2 released in cement manufacture https://www.abc.net.au/news/science/2016-11-22/concrete-is-a...

Couldn’t you also easily capture the co2 when making the lime? It seems like it would all be in one place in a controlled environment.

The CO2 is of high quality because it is not coming from a burning something process and there is a huge amount of residual/excess heat from the calcination process.

Perfect for algae production!

Easily maybe not, but it would be a great place to start with carbon capture technologies.

Yes, but you may not have a cavern to compress it into.

You need to add the CO2 released due to energy usage in both processes. It’s quite intensive. I wouldn’t be surprised if over it’s useful life cement only capture an amount equivalent to quarter of what it generates.

its to the point where i'm consciously trying to not engage in the facts debate or the what-about-foo endless spiraling. we're over-complicating things and enabling the "debate" to continue to waste precious time.

coal need to end within a decade. oil needs to be cut in half within a decade. anything else is a distraction.

In particular, anything about single-use plastics is mostly a distraction. There's something to be said for the emissions cost of delivering and disposing of them, but in general, sucking oil out of the ground, turning it into plastic objects, and then burying those plastic objects back in the ground is a "complete lifecycle", much more so than releasing that oil's carbon into the atmosphere via combustion.

All the more so if the plastic objects are mostly buried alongside other plastic objects where they can be dug up and reprocessed later on as the need arises.

Except single use plastics don't end up in the ground reliably: they end up in water ways, beaches, wetlands and the oceans. They degrade into micro plastics and then end up in the food chain.

They are a huge problem for non-emissions reasons.

Oh yeah, they're definitely a problem, and work should be done to reduce and eliminate them. But they're not directly a climate change problem.

Also, if you live in a major western city, especially a non-coastal one, your garbage is pretty reliably ending up in a landfill. 90% of river-borne plastic pollution comes from just 10 rivers, all of which are in Asia and Africa: https://www.weforum.org/agenda/2018/06/90-of-plastic-polluti...

This is not a get-of-jail-free card to the rest of the world, but it does change the nature of our responsibility— in particular, it means that individual action is almost entirely worthless. Because the issue in the west is not the trash, it's that we're culturally exporting a single-use lifestyle that creates all that mess when it is imitated in places without the pipeline in place to manage the waste. So what is needed is a collective cultural change in order to alter what we export via our media, and the actions/expectations of our politicians, celebrities, tourists, etc.

Also natural habitats need to be protected. I'm so sick of plastic straw theater though. Plastics barely matter at all for the environment!

The problem is already solving itself as well as it can.

The world is running out of any fossil fuel except natural gas which can be extracted more cheaply than the various types of renewables.

With $100 USD/bbl oil you don't need protests and activism to switch away from fossil fuels, simple economics will drive energy choices. Saudi Arabia is going to run out, and it is likely they have been exaggerating their reserves and production capacity for political reasons. It won't take much to explode the price of oil and people know it and are planning for it.

Why wait? Just tax it.

Why wouldn't be want to tax the destruction of something instead of work/labour/selling stuff?

The world has way, way more coal left than we can afford to burn.

> The world is running out of any fossil fuel except natural gas which can be extracted more cheaply than the various types of renewables.

That seems to be sort-of true, but mostly in the sense that renewables are getting cheaper. Fossil fuels don't seem to be getting that much more expensive. Mostly because the long run supply is actually fairly elastic.

Saudi Arabia claims 250-300 billion barrels of viable oil reserves, and it's currently pumping about 4 billion per year. There is also credible doubt to those numbers with some saying they may be greatly exaggerated for political reasons. It is very possible the all time high of ~11 million barrels a day in Nov 2018 will never be surpassed.

There is a lot of oil around to be extracted, it won't "run out" but it is absolutely not elastic, and not at arbitrary prices. The big reserves which remain are considerably more expensive to extract and convert to a usable state. The $100/bbl rate is somewhere around the floor price for the oil economy when those resources dominate. The price of fossil fuels has bounced around in the last decade or two for political reasons. OPEC was forcing prices above $100 because they're a cartel but then North America found an enormous quantity of tar sands and similar kinds of expensive-to-extract but in huge quantities, it was profitable to extract at those prices and OPECs cartel price highs were broken because they could not afford to cut production in order to raise prices (much of OPEC proping up their power with money that they couldn't do without).

OPEC is running out of cheap oil, the world is running out of cheap oil. There is an enormous amount of oil left in the ground which can be extracted, but at a price. A price which is easily beatable by renewables now and definitely in the future when scaling and technology factors further lower their prices.

Fossil fuels are over, it's done. There's little left to protest or try to change, the situation is forcing it and it can be seen by anybody in the energy business. If you want to burn public money you can accelerate the process a bit with taxes and tech development (this is already being done and it could be done a bit more) but ultimately the future doesn't depend on that, just a bit of timing.

We mostly agree on everything, we just use different terminology.

I do agree that the Saudi Arabian numbers deserve some doubt.

When I say that the supply of oil is elastic, I am talking about https://en.wikipedia.org/wiki/Price_elasticity_of_supply

Elastic in this context means that an increase in the price will bring forth more supply. That's very much the same thing as your statement that we are running out of cheap oil.

In the short run, oil supply and demand are very inelastic. That means that even if oil prices were to double for a week, it wouldn't much change the amount of oil consumed nor the amount of oil produced.

It takes a while to explore and exploit new oilfields, and it takes a while to shift consumption to and from oil. Thus in the longer run, say over a few years, oil supply and demand are much more elastic.

Especially if you add in new technologies, like we saw with fracking.

The longer run being more elastic than the shorter run means that the longer running price is more stable than in the shorter run. (Of course, more stable doesn't mean constant. We still see the secular rise in real oil prices.)

That's all still totally in line with everything you say.

Now you correctly mention that renewables are getting cheaper. For most applications, you just want power say for electricity generation, so you can easily substitute renewables (or coal..) for oil. That further contributes to long running stability of the oil price.

For some applications like fueling cars, or even more so: planes, carbohydrates are harder to replace. So they get substituted later, or perhaps never; depending on how effective relative prices (including taxes and reputational effects) move.

(In principle, we don't need fancy electric batteries: you can use electricity from renewables to synthesize aviation fuel from scratch. It mostly just carbon and hydrogen. It's not just worth it at the moment, and might never become worthwhile.)

I'm all in favour of replacing fossil fuels with renewables. My point is just that the market driven replacement comes mostly from renewables becoming cheaper, less so from fossil fuel becoming more expensive.

> If you want to burn public money you can accelerate the process a bit with taxes and tech development (this is already being done and it could be done a bit more) but ultimately the future doesn't depend on that, just a bit of timing.

Yes. Though I do wish we had a carbon tax, even if just a low one. Not just for any of the effects of steering people away from fossil fuels, but to show that combating climate change should be a money-spinner for the government, not a money sink. That should make it easier to argue against government efforts of trying to pick winners like the pretty much useless German photovoltaic subsidies of the past: Germany is not known for its long days of blasting sun..

(And about competitive effects in regards to other countries: just treat the carbon tax like VAT when you adjust for products and services crossing borders.)

Also, fracking is new huge source of natural gas that wasn't exploitable before.

Reply on news.ycombinator.com