This article isn't very clear on the fact that CO2 can be re-injected back into the cement later in the production stage. I work with a startup using direct air capture tech to capture ambient CO2, store it, and inject it back into cement production. This has a massive offset in the CO2 produced during the calcination stage.
There is also lots of work already underway on electrified calcination. Plenty of industries, such as carbon fiber production, already take advantage of electrified kilns in their production process. This tech just needs to be scaled up. As the article mentioned, cement manufacturing isn't exactly on the cutting edge of technology.
> This article isn't very clear on the fact that CO2 can be re-injected back into the cement later in the production stage.
How can that work? The calcium oxide (or hydroxide) reacts with silica to make silicates, which bind things together. That CaO which reacted is not available to soak up CO2.
In this particular case the CO2 mineralization is taking place in a wastewater slurry that comes from washing out cement trucks. The carbonated slurry is then re-used as an additive by cement manufacturers.
Won't cement slowly reabsorb half of the CO2 it released when making it (excluding the heating part)? What is the big advantage to making it reabsorb it early in its lifetime?
1. That’s a big half
2. The heating part releases an incredible amount of carbon
(If I can dig up some solid links after dinner I’ll edit the post. But Chris Magwood at The Endeavor Center has some fantastic reference material for lifecycle carbon intensiveness)
Last time this was mentioned someone claimed this drastically reduces the strength and lifetime of the concrete, effectively pre-aging it and is probably a wash in terms of carbon savings.
The best way to reduce carbon emission from cement would be to use less of it.
Here in the UK, 30% of the cost of a new house build is the foundations, the excavation, and then filling of a hole in the ground with many tons of concrete. I find it baffling how little innovation in construction has been adopted by the house building industry here. Light weight timber frame construction on pile foundations would massively reduce both the carbon footprint of the build and the cost.
When I have made these arguments before, people often respond that our heavy weight brick construction is better as it withstands the weather more, and will last longer. But with modern materials (or good old traditional maintenance) thats just not true, a timber frame house can last hundreds of years.
Finally, it's not just the carbon emissions from cement manufacturing that worries me. I live about 3 miles from a cement factory, and the amount of dust that it puts out is staggering. If I clean my car, within two days it's covered in a thin layer of dust thats locally attributed to the factory. I can't imagine thats good for our health!
For regions that don't have to worry about a frost line helical screw piles and mass timber are game-changing building capabilities to construct concrete free. It's even possible to build carbon negative thanks to the timber locked in the building. And it's way faster since you don't spend months preparing a site and building forms.
Even frost line regions could dramatically cut their concrete usage if they just focused on protecting the water lines. You would lose a basement, but those are expensive per sq ft anyway. Just go up another floor for less total costs.
Local building codes will get in the way since building inspectors tend to reject things they haven't seen before (like mass timber frame) and way too many places have incredibly strict height restrictions.
It is incredible to watch helical screw piles go in. A friend needed 60+ posts installed for a big fence. Would have been days of digging or augering post holes down 4 ft for the frost line and then mixing hundreds of bags of cement and filling the holes with concrete. Instead a contractor with a small tracked machine that fit through a standard gate drove every pile in under an hour.
Absolutely true, but you still need a plan for protecting the water lines. You need some kind of underground insulated structure below the frost line that can handle direct dirt contact. Annoyingly concrete remains the best option.
Was recently in a fairly new construction house in a very cold climate state that did not have a full basement below the frost line. There was a partial 8’x8’ corner that sunk down to where the water line came in, but the rest of the footprint was a crawl space. Losing the basement does affect the style of building that is economical to build on top though, mainly due to building codes.
I live in an area with freezing weather. The water pipe to my house is just a PVC pipe buried below the frost line, i.e. in a trench about 3 or 4 feet deep. There's no concrete involved.
>And it's way faster since you don't spend months preparing a site and building forms.
What size house are you building that it takes months preparing a site to build foundations? Sub 2000sqft houses are built to completion in 90-120 days if weather doesn't delay things. It only takes a couple of weeks from clearing the site, digging the trenches, lining the moisture barrier, laying the rebar and forms, then pouring the cement. The formulas today cure very quickly. From the day of the pour to the start of framing is practically the blink of an eye
Here in Canada it’s extremely common for ground works for a new subdivision to take over a year.
Individual houses can be done in a much shorter time, but digging a basement, setting all the forms, pouring the concrete, waterproofing the walls, underpinning the water management, and then back filling back to grade is not a quick process.
You're comparing the time it takes a developer to clear the entire development to the time it takes to build a single house. These are not the same thing. That's comparing apples and oranges. Comparing the time for a house with no basement to one with a basement is comparing a granny smith to a red delicious.
That's about as fast as maple syrup. The ground around here never gets that cold, and basements are not a thing at all. So your 60 days is about 45 days behind schedule! Your sub-contractors are bilking the contractor ;-)
There is a good argument that buildings shouldn't last so long.
Buildings a mere 50 years ago probably have very poor insulation (and hence high heating/cooling environmental + monetary costs), have electrics that aren't considered safe today, have plumbing probably containing lots of lead, and are lacking amenities considered standard today (electrical outlet next to the bed for phone charging, mixer taps, etc). Those buildings probably won't resist fire for long, and probably won't be suitable for heat pump heating. Sound insulation probably won't be good, so you probably get woken by your neighbour having sex.
All those things are fixable for a cost, or livable with a hit to quality of life, the environment, the house owners health, etc.
If we assume that the requirements for a home continue to evolve, then we can see that something built today would be unlikely well suited for use in 50 years. Considering that, perhaps it's best to build something easy to disassemble and rebuild 50 years from now.
Sound insulation in older homes is much better than in new. Thicker and heavier materials are much better at absorbing or reflecting sound, especially low frequency. Fire resistance seems to be a wash. I've seen the aftermath of new and old construction. We don't seem to have made improvements in this regard, but we have made the likelihood of them starting lower in all kinds of construction.
The opposing argument for much of their down-sides is the up-front cost of building a new home has it's own environmental and financial costs. Much of the down-sides to older homes can be retrofitted for substantially less cost and impact than a new home.
We could get the best of both worlds by designing homes for upgrades with large conduits for wirings, easier access to walls and attics, etc.
The best apartment building I ever lived in in NYC was built in the 1920s and was built "naturally fireproof", where there were thick masonry walls between each unit to prevent the spread of fire. I literally never heard a single neighbor, anywhere, ever. Not my same-floor neighbors, nor the people above or below me.
Compare that with newer buildings I lived in, where I would be woken up at 3AM by my upstairs neighbor's cat running around.
Doing all those things at once, it's usually cheaper to knock down and start from scratch.
The problem lies in a homeowner who doesn't have much spare cash - so they rewire one year... and then a few years later they replumb... and then a few years later they replace the roof... etc.
Overall, they spent more, but in small increments so it didn't feel like more.
Typically regulations allow things to be 'grandfathered' - so renovating a house allows you to avoid getting permission to rebuild, which may be denied.
The idea that periodic replumbing and rewiring and replacing roofing felt costs less overall than a complete rebuild is questionable enough in terms of financial cost, even more so in terms of carbon output cost.
Sure, the [carbon] accounting looks a little different if you're having to pull out most of the load-bearing walls to accommodate a change of use and underpin to build on top or considering replacing old masonry with something built to maximise energy efficiency. But rebuilding entire houses to keep up with the latest fads in mobile charge ports and mixer taps is about as good for the environment as "fast fashion"!
Beyond finances, there's simply the nightmare of -- where the hell do I live while my house is being rebuilt? We've put off kitchen & main floor renovations for a half decade simply because we don't want to deal with the hassle, a rebuild is another thing entirely.
Many houses are naturally unused for months at a time - for example between tenants if let. Between owners when sold, or after the inhabitant passes away.
> Doing all those things at once, it's usually cheaper to knock down and start from scratch.
This has never been my experience. I've done a lot of this kind of work, in several different cities (all US though).
A full rip & replace of plumbing, electrical, and roofing should cost about 20%, and require about 10% of the time, compared to building new.
Plumbing should last 50 years (rough plumbing -- fixtures are decorative and usually change with taste before failure). Electrical should last longer, but systems older than 1970s probably need updating. Roof should last 25-30 years depending on style/material.
> Doing all those things at once, it's usually cheaper to knock down and start from scratch.
This must be regional. In the PNW we'd never knock something down for that. Stripping the drywall out and redoing the plumbing/electrical/insulation is quite a lot less expensive than putting up a whole new structure.
My house was built in 1885, timber framed. There's no rot, it's been maintained, re-plumbed and re-wired a few times, and new owners only need to keep with basic maintenance. It's been insulated as well, utility bills are in the $90-150 range depending on how extreme the seasons get. The structure has another century left in it, easy.
> Light weight timber frame construction on pile foundations
> But with modern materials (or good old traditional maintenance) thats just not true, a timber frame house can last hundreds of years.
I am not sure were you are reading that "timber frame house can last hundreds of years" but I don't believe that is correct, most timber frame houses have an estimated 30 year life span. A stone/brick house can last thousands of years.
I do agree that a stick frame/light weight timber house is way less concrete then a brick/stone house. But UK doesn't have a ton of trees, so the majority of those trees are imported from EU places like Belarus or Canada. Which is a bunch of gas in itself.
Pile foundations also have tons of problems, and have a very high fail rate. They don't do well with salt water, so costal areas in UK will have problems, they don't do well with stone/bedrock. Which UK has a ton of.
I believe there is tons of work to do, but I disagree that the solution is stick framing and pile foundations. I think the actual solution is innovation and reduction of some building standards to allow innovation. It's very very difficult to even experiment with building materials as every building code requires X insulation and any building official will complain if you have Y. So everyone just uses X.
ICF for example is absolute garbage, its marketed as a eco friendly, green building material that's made from oil and filled with a truck load of cement. How that got classified as a "eco-friendly green building material" is beyond me.
Meanwhile things that are actually eco-friendly like hemp, straw, etc all require a ton of engineering and have zero standards, so everything has to be engineered. And you'll get crazy looks from building officials when you ask for a review of your straw timber frame house.
I live in a ballon-framed house built in 1926. Coming up on 100 years and with reasonable maintenance there is no reason it won't last another 100. There are some terribly built wooden houses that will just rot away, but it's not that hard to do it right.
Wood as a building material when used properly can be incredibly resilient, especially with modern mass timber solutions rather than raw wood.
Agree. My first house was a wood-frame bungalow built near the prior turn of the century. As long as you don't get termites, and maintain the roof and siding so you don't have water leaking in, wood houses will last basically forever, or at least on the order of 100 years.
Modern mass timber more than corrects that problem. It does a fantastic job using fast growing, new growth lumber to produce highly precise parts that are factory produced exactly to spec to nearly eliminate waste.
Highly precise lumber parts sounds like an oxymoron. The standard assumption for wood is that it's only straight while it's being cut. If they've invented fix for that, it's not gonna be the wood that they're using that does it, but some extra processing to make like a particle board or something
Modern mass timber has advanced a long way beyond cheap particle board. Read up on cross laminated timber. Manufactured and cut exactly to size and often requires no cutting on site.
Laminated strand is certainly under the heading of mass timber, but I’m referring more to cross laminated timber (CLT). It still uses resin, but with much more wood it doesn’t suffer from the sort of rot and de-laminating problems OSB has, but it’s still highly engineered and highly precise like LSL.
Laminated veneer lumber (LVL) has become common in North America for beams and joists. CLT uses even larger components and is even more flexible. It’s just starting to be used but you can build everything from a house to 20 storey buildings.
> I am not sure were you are reading that "timber frame house can last hundreds of years" but I don't believe that is correct, most timber frame houses have an estimated 30 year life span. A stone/brick house can last thousands of years.
I grew up in a four family timber house built in the 1960's. It's still standing. As are all the houses on that road which were all built at the same time. We moved to a timber house built around 1910. It's still standing - I walked past it just last year. My grandparents lived in a development of all wooden houses built in the 1950's. They're all standing.
Where did you get this notion they have a life span of 30 years? Norway has plenty of wooden houses that have stood for a 100+ years, and a huge bulk of post-war construction from the 50's and 60's in wood.
On the more extreme end, there are a number of stave churches in wood dating back to the 1200's. Of course they're the outlies that survived, and have certainly required maintenance.
EDIT:
Here's a list of stave churches in Norway, and construction years. Some of these have been rebuilt during that time, but even those that have typically have a lifetime of each iteration measured in centuries, with a few exceptions:
As a fun curiosity, here's Vang stave church, "moved" from Norway to Poland in 1842, originally built in the 1200's. "Moved" because most of the material ended up being discarded because the builders handling the re-erection didn't quite know how and found it easier to replace most of it. So the current iteration is really "only ~180 years old, and might have been moved and rebuilt once before, but in any case each iteration survived rather a bit longer than 30 years:
The life span is probably more due to the lifespan of the plumbing. On high-grade copper(L- or K-) you can get a useful life of 50 years but PEX is only rated for 30 years, and the lowest grade of copper(M-type) has a similar replacement interval. The valves used in plumbing fixtures also wear out and need replacement periodically. And the valve housings do as well. The anode in a water heater will probably only last a couple of decades. These are all replaceable parts.
Siding is in a similar state, with many modern sidings have replacement intervals in the decades, and shorter time periods if you don't paint every 5-10 years.
If properly maintained and if parts are replaced in a timely manner a house can last indefintely. My partner and I own a house from 1935 that was last renovated in the 1990s, and I'm starting to have to make minor plumbing repairs. I think in the next 10 years or so we'll have to re-pipe and re-wire. But the framing and sheathing is almost all original, except for the roof deck which was replaced first in the 1990's and then parts were replaced when we re-roofed last year(the original roofer did not know how to frame to support a rake board).
Everything also changes if you factor in repainting and replacement of interior fixtures.
But still, if you maintain it and factor in all these repairs and replacements your house can last for hundreds of years.
For what it's worth, I have a 200 year old cottage that probably has a few centuries left in it, and the plumbing and wiring is all in conduits that are easily accessed. Maybe we should make it easier to replace this stuff without ripping the house apart?
Different climate but I lived in two poorly maintained Queenslanders[1] which were a popular style of timber on piles here, both 50 years old and would easily last longer. One even had minor termite damage which was later treated.
Many people here do knock down rebuilds but most would easily last longer than 30 years. Many timber houses get re-stumped after a few decades and concrete piles seem to be a popular choice for replacement.
I see a lot of poorly built homes on slabs as well which seem to have a similar lifespan as the Queenslanders (anecdotally).
Timber frames can definitely last hundreds of years. I have multiple family members on my wife's side who live in houses with parts dating back 100-200 years. They've been kept up and more or less continuously occupied, but it's not as though that meant continuously conditioned as we would think of it until sometime in the 20th century.
Hell, you can drive through New England and see barns that are 150 years old that are only starting to fall down after 50 years of deferred maintenance.
If you keep wood dry, it'll last a good long while. Whether you consider 100-200 years a long time, will of course depend on perspective:
"In Europe, they think 100 miles is a long way. In the US, they think 100 years is a long time."
> I am not sure were you are reading that "timber frame house can last hundreds of years" but I don't believe that is correct, most timber frame houses have an estimated 30 year life span. A stone/brick house can last thousands of years.
I have in fact lived in a timber frame house that was 400 years old and going strong. No idea about its history, but it was rather comfortable and cozy. It wasn't particularly well insulated though.
Cement is used in most city infrastructure, for industrial builds, etc. The demand for it in the U.S. probably dwarfs the UK several times over despite lumber use for houses, and poured concrete no longer popularly used for foundations.
If you want to abate it, you'd need to look far beyond that particular use-case in the UK. I don't see low-hanging fruit here. Cement is reliable and inexpensive. There is R&D in the works for eco-cement, but this appears to be in early stages.
It's possible to reduce emissions in its production in the first place. Notwithstanding the calcium carbonate, energy inputs (which are very high) could eventually not rely on fossil fuels.
If the goal is to pursue an aggressive timeline for curbing CO2 emissions then probably CC & electrical will appear first.
Correct, timber is expensive here - particularly over the last 3 years - but I believe a timber frame construction is still a little lower than a brick contraction in cost. SIPs (structurally insulated panels) are more expensive than brick, but I suspect that more to do with available expertise and the need for expensive cranes. (As an aside its fascinating visiting France where every house building site has a crane, none do here)
But many timber frame houses here are still build on massive concrete slabs, and that is still pouring money into the ground. We need to adopt innovations like screw piles that are completely concrete free.
I had a house built in Ireland and the architect was a huge pain in the ass. She wanted concrete _ceilings_ ffs. In a single story dwelling. She also thought it was ludicrous I wasn't using concrete blocks, and anything like a pier or post and beam foundation was completely out of the question.
The funny thing is that the houses here are pure shite so it's not like this approach has been working for them. Utter, abominable, crap. Ugly, too.
I was able to get a timber frame and wood ceilings but still have a concrete foundation. The builders were so proud of it being an insulated foundation (KORE) but you wouldn't even _need_ that if the house were lifted off the ground, like it should be.
I asked one forward-minded engineer about it and he said it was down to people being brainwashed by "concrete built is better built" ads from the 80's and centuries of complete deforestation.
> The best way to reduce carbon emission from cement would be to use less of it.
Disagree.
I think we need to return to the future through rediscovering Roman Concrete [1] and making structures that can last thousands of years.
Concrete also, can be recycled and used again.
Because we are in a deglaciation period currently, in general I am skeptical about moving to a low CO2 environment which is not normal for the earth. However, I am sensitive to the fact that we must be stewards and caretakers of the earth and make the best use of resources, while polluting less, and moving to a more sustainable future through a grand conversion process eventually.
Same reason most people don't write Rust: The talent, best practices, and vendor ecosystem are less accessible. Similar to Rust it's much more accessible than people _think_ though
"Seawater desalination concentrate—a new frontier for sustainable mining of valuable minerals" (2022)
> "The metallic elements found in the highest concentration are sodium, magnesium, calcium and potassium, which have been commercially extracted as the chlorides, sulfates, and carbonates while magnesium has been extracted as the hydroxide."
The most interesting thing I saw in that article was the rotating air heater. Induce turbulence and shock waves in air and heat to very high temperature, without having a resistive heating element that has to be at least that hot.
If you are going with electrical energy -> heat, you can get energy storage for free. It's much cheaper to store a kWh of high grade heat as sensible heat than it is to store a kWh of electrical energy in a battery. So electrification of cement production will be able to act as a large amount of dispatchable demand, simply by tacking on a heat store.
I think it is interesting to see that hannob who wrote many articles on IT security now seems to have pivoted to covering ‘green and energy’ topics. All submissions to HN in the last year are not about IT!
Even if you want to increase density, you'd need concrete to achieve it. Cost of housing is inversely correlated to the rate of new builds in cities, and the reason is the growth in demand through immigration. Can't have your cake and eat it too: want more immigration? Build more.
> a social solution
Such as what, coercing multiple families to share detached homes? Would you volunteer for that? And how far do we expect to push that when the demand for housing will keep growing?
Apartments work fine? In lower density areas simple duplexes or quadplexes work fine. We don't need every single family living in an isolated home with the white picket fence.
We have more than enough homes. There are over two dozen empty homes per homeless person. It's not just an issue of building more. Shelter is being treated as a speculative asset and the only meaningful vehicle for building weath in the middle class. Hence the need for a social solution.
You must be familiar with the monumental amount of concrete these require, yes? They are more dense, but not "low-carbon" by any stretch.
> We don't need every single family living in an isolated home with the white picket fence.
Families can decide for themselves what suits them. It's not your place to tell someone they don't "need" something. You don't "need" most of your possessions. Hell you don't even "need" a roof over your head, as it pertains to survival.
And we sure don't "need" to race to the bottom and demand lower qualify of life from everyone. Not for homelessness, and not for building efficiency. It does not solve anything. It's purpose is in-group virtue signaling.
> We have more than enough homes.
If that were true, more people could afford them. Affordability scales with the rate of new builds.
> There are over two dozen empty homes per homeless person.
Notwithstanding that this is unsourced, lodgment =/= home ownership and homelessness is its own special problem that includes factors beyond cost.
> Families can decide for themselves what suits them.
But they only can choose from what gets built, and what gets built is ultimately a function of what builders consider profitable and what legislation allows. And what legislation allows is based, to a significant extent, on what infrastructure can be provided to support particular types of residences. If a government decides it can't be bothered (or afford) upgrading or building the necessary infrastructure to support more apartment dwellings then families aren't going to get to choose living in them.
Similarly, what's profitable depends on how taxes and other fees are levied from profits made by property developers and owners etc. Families don't get much choice over that either.
> a function of what builders consider profitable and what legislation allows
Change legislation (qua zoning, qua regs) and you increase the rate of builds, which should adequately meet current demand. Of course, the laws of physics are in play - if the immigration rate is high, thereby perpetually increasing demand, you still won't build fast enough.
This is what YIMBYs have to remember about Japan, which they frequently cite. The population doesn't grow much. Can't have it both ways: build, or reduce immigration.
We could add taxes for cement that could be redirected to a carbon dividend.
There is a environmental cost that we are not paying when we build houses, and having a tax it's a fair way to incorporate this externalities. I don't trust the state with the money from this taxes so lets share them equally with the population.
We can do the same with aviation that would also reduce speculation of the house prices.
Those are policy decisions, not the sort of "social" changes alluded to by the other users. Variations on these tax schemes are already enacted and are likely to be expanded. It's nothing new.
> I don't trust the state with the money from this taxes so lets share them equally with the population.
This doesn't make any sense. You want the State to tax you, presumably trusting them to do that, but you don't want the State to manage tax revenue? The point of tax revenue isn't just redistribution (you seem to be gesturing towards UBI), no one should have to explain that.
- Significant net movement of people (e.g. the UK took in 0.6m immigrants in 2022, pushing up housing requirements) resulting in more houses being needed in some locations even if the world had zero extra people
- Cement isn't reusable, so once it's set it's only useful in that place
cement ≠ concrete, but concrete is indeed recyclable. I know TxDOT (likely other agencies and municipalities) allows its use, often as aggregate material for HMAC paving. The cured concrete is crushed, sorted by gradation and used accordingly. Concrete rubble can also be used in retaining walls along with some backfill applications.
That is true for a lot of western countries but we are expect to produce and consume more concrete until 2050 then we did so far in history in developing countries.
We need as many ways to theoretically cut emissions as possible. That way, no one way will ever have to be chosen by a majority of people. So we will never have to actually do any of them. And we can keep polluting but pretend "it's not my fault because I supported <insert random niche idea>".
No one wants to admit they are happy to just ruin everything. So we all need to pretend we want action. But in order to prevent any action happening we need to pick different things.
The Nuclear people won't vote for solar expansion, the solar people will deny windmills work, the windmill people will refuse to condone nuclear. That way EVERYONE can claim the moral high ground AND use nice cheap, reliable coal. The same applies for everything (electric cars? No! Hydrogen!. Hydrogen? No, public transport! Public transport? No, electric cars!).
Quoting this from an article by Australia's chief scientist Alan Finkel:
Between 1990 and 2021 the behemoth known as global civilisation only reduced its fossil-fuel diet from 87% to 83% of total energy consumed worldwide. Let me spell that out. We shaved off 4% in the last 30 years. In the next 30 we need to shave off 83%.
https://www.carbon-direct.com/insights/direct-air-capture-to...
There is also lots of work already underway on electrified calcination. Plenty of industries, such as carbon fiber production, already take advantage of electrified kilns in their production process. This tech just needs to be scaled up. As the article mentioned, cement manufacturing isn't exactly on the cutting edge of technology.