This Lab-Made Mineral Just Became a Key Candidate For Reducing CO2 in The Atmosphere
Scientists just worked out a way of rapidly producing a mineral capable of storing carbon dioxide (CO2) - giving us a potentially exciting option for dealing with our increasingly overcooked planet. Magnesite, which is a type of magnesium carbonate, forms when magnesium combines with carbonic acid - CO2 dissolved in water. If we can produce this mineral at a massive scale, it could safely store large amounts of carbon dioxide we simply don't need in our planet's atmosphere.
[...] Being able to make the mineral in the lab could be a major step forward in terms of how effective carbon sequestration might eventually be. "Using microspheres means that we were able to speed up magnesite formation by orders of magnitude," says [Ian] Power. "This process takes place at room temperature, meaning that magnesite production is extremely energy efficient."
[...] With a tonne of naturally-occurring magnesite able to capture around half a tonne of CO2, we're going to need a lot of magnesite, and somewhere to put it all as well. As with other carbon capture processes, it's not yet clear whether this will successfully scale up as much as it needs to. That said, these new discoveries mean lab-made magnesite could one day be helpful – it puts the mineral on the table as an option for further investigation.
Related: Negative Emission Strategy: Active Carbon Capture
Carbon Capture From Air Closer to Commercial Viability
Related Stories
http://www.technologyreview.com/news/531346/can-sucking-co2-out-of-the-atmosphere-really-work/
Discusses the scientific and economic feasibility of using methods to actively capture carbon dioxide from the atmosphere. Also the article discusses the possibility that carbon dioxide harvested from the atmosphere can be sold on the market competitively, and thus engage the private economy in countering man-made climate change.
I wonder if a consequence of profitable harvesting of carbon dioxide from the atmosphere might be that it could lead us into an ice-age.
Sucking carbon dioxide from air is cheaper than scientists thought
Siphoning carbon dioxide (CO2) from the atmosphere could be more than an expensive last-ditch strategy for averting climate catastrophe. A detailed economic analysis published on 7 June suggests that the geoengineering technology is inching closer to commercial viability.
The study, in Joule, was written by researchers at Carbon Engineering in Calgary, Canada, which has been operating a pilot CO2-extraction plant in British Columbia since 2015. That plant — based on a concept called direct air capture — provided the basis for the economic analysis, which includes cost estimates from commercial vendors of all of the major components. Depending on a variety of design options and economic assumptions, the cost of pulling a tonne of CO2 from the atmosphere ranges between US$94 and $232. The last comprehensive analysis of the technology, conducted by the American Physical Society in 2011, estimated that it would cost $600 per tonne.
Carbon Engineering says that it published the paper to advance discussions about the cost and potential of the technology. "We're really trying to commercialize direct air capture in a serious way, and to do that, you have to have everybody in the supply chain on board," says David Keith, acting chief scientist at Carbon Engineering and a climate physicist at Harvard University in Cambridge, Massachusetts.
A Process for Capturing CO2 from the Atmosphere (DOI: 10.1016/j.joule.2018.05.006) (DX)
Direct Air Capture of CO2 with Chemicals (2011)
Earlier this week, Y Combinator, which has backed companies like Airbnb and Reddit, put out a request for startups working on technology that can remove carbon dioxide from the atmosphere.
"It's time to invest and avidly pursue a new wave of technological solutions to this problem — including those that are risky, unproven, even unlikely to work," Y Combinator's website says.
Y Combinator is looking for startups working on four approaches that they acknowledge "straddle the border between very difficult to science fiction" — genetically engineering phytoplankton to turn CO2 into a storage-ready form of carbon, speeding up a natural process in which rocks react with CO2, creating cell-free enzymes that can process carbon, and flooding Earth's deserts to create oases.
Sam Altman, the president of Y Combinator, acknowledged that these ideas are "moonshots," but said that he wants to take an expansive approach to the issue.
Related: Negative Emission Strategy: Active Carbon Capture
Storing Carbon Dioxide Underground by Turning It Into Rock
A Startup is Pitching a Mind-Uploading Service That is "100 Percent Fatal"
Carbon Capture From Air Closer to Commercial Viability
Y Combinator Spreads to China
Lab-Made Magnesite could be Used for CO2 Capture
NASA Announces CO2 Conversion Challenge, With Up to $750k Awards
Climate Change: 'Magic Bullet' Carbon Solution Takes Big Step:
A technology that removes carbon dioxide from the air has received significant backing from major fossil fuel companies.
British Columbia-based Carbon Engineering has shown that it can extract CO2 in a cost-effective way.
It has now been boosted by $68m in new investment from Chevron, Occidental and coal giant BHP.
[...]CO2 is a powerful warming gas but there's not a lot of it in the atmosphere - for every million molecules of air, there are 410 of CO2.
While the CO2 is helping to drive temperatures up around the world, the comparatively low concentrations make it difficult to design efficient machines to remove the gas.
Carbon Engineering's process is all about sucking in air and exposing it to a chemical solution that concentrates the CO2. Further refinements mean the gas can be purified into a form that can be stored or utilised as a liquid fuel.
(Score: 3, Informative) by c0lo on Monday August 20 2018, @10:21AM (19 children)
Magnesite is already a carbonate, MgCO3. What reaction do they plan to use to make it take another CO2?
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 4, Informative) by takyon on Monday August 20 2018, @10:32AM (18 children)
Magnesite is the end product. The sequestration process is taking CO2 from the atmosphere and permanently storing it as magnesite. The advancement was creating magnesite artificially by using polystyrene microspheres as a catalyst, which took 72 days vs. typically hundreds or thousands of years for natural formation.
If this was done on a large scale, my guess is that the main application [wikipedia.org] would be as a building material.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2, Insightful) by fraxinus-tree on Monday August 20 2018, @10:43AM (13 children)
The idea is a chemical nonsense.
It is almost impossible to find (on Earth) magnesium that is not already a carbonate. To make it absorb CO2 you have to first remove CO2 from it, releasing exactly as much CO2 as it is able to absorb later. And removing CO2 from magnesium minerals is an impressive energy hog, so we'll get even more CO2.
In practice, what they got is a repeat of the lime process, used in construction for the last millennium or two. They just replaced calcium for magnesium - good for them, but completely unrelated to CO2 capture.
(Score: 5, Informative) by takyon on Monday August 20 2018, @11:05AM (11 children)
Are you sure?
Seems like the main source is magnesium oxide [wikipedia.org], which occurs naturally and contains no carbon.
If the process chosen is energy intensive, then you simply have to use solar... or fusion.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by BananaPhone on Monday August 20 2018, @02:18PM
Solar == Fusion by proxy
(Score: 2) by fritsd on Monday August 20 2018, @04:33PM (9 children)
The energy equation is way out of whack. Like this:
Procedure 1:
- use solar or fusion to create energy.
- forget about the Magnesium.
vs:
Procedure 2:
- dig up oil or coal
- burn the oil or coal for (lots of) energy and lots of CO2
- dig up special Magnesia ore [wikipedia.org] that isn't weathered yet
- use solar or fusion to wash and react the CO2 with the Magnesia ore to create Magnesite (not very energy intensive, sounds like it's a bit exothermic, and these people found a catalist)
- dump the Magnesite somewhere, or make cinderblocks from it or something
I can't prove it from such a crude summary, but I suspect that the thermodynamics and therefore the money side of the equation only works, if you postulate that you absolutely *must* somehow burn oil and coal in the first place.
I'm not saying that CCS doesn't work; only that it might be more expensive than to just leave the fossil fuels in the ground in the first place.
(Score: 2) by takyon on Monday August 20 2018, @04:46PM (8 children)
^^ Note that you can get it from desalinization, which gets you some other useful products. You don't have to dig it up.
The money might be worth spending *if* the process does decrease CO2 overall and you put a high value on lowering that number.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 1, Insightful) by Anonymous Coward on Monday August 20 2018, @05:31PM (4 children)
Magnesium is present in seawater at concentrations of about one part per thousand. So you can get about one tonne of magnesium from one thousand tonnes of seawater.
Estimating from standard atomic weights gives that magnesite is about ⅓ magnesium by mass. So to get one tonne of magnesite you could get the required magnesium from about ⅓ kt of seawater.
TFA says one tonne of magnesite will sequester about half a tonne of CO₂ (assuming you can produce it with zero carbon dioxide emissions). This is consistent with the atomic weight estimates.
To get enough magnesium from seawater, then, to produce the 8 billion tonnes of magnesite [soylentnews.org] per year required to offset human breathing, you must process about 3 trillion tonnes of seawater per year. That's on the same order of magnitude as the global freshwater water usage by humans.
So if we were to replace literally all modern human uses of freshwater aquifers and essentially all other natural sources of freshwater with desalination, and do it all with zero carbon emissions, then maybe we'd be processing enough seawater just to produce enough raw material for this carbon sequestering process from seawater to offset human breathing
(Score: 2) by takyon on Monday August 20 2018, @06:33PM
Yeah, might be easier to start injecting sulfur compounds [technologyreview.com] into the upper atmosphere.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2) by Zinho on Monday August 20 2018, @06:37PM (2 children)
That's good news, then! Our friends at El Reg have done the math, and it already looks favorable economically to replace natural water sources with desalination in places like California [theregister.co.uk] and London. [theregister.co.uk] What's holding us back is the sad fact that the energy used to do so would lead to release of CO2. If replacing our drinking water offsets our CO2 use, then we're into two-birds-one-stone territory.
Naturally, it would be better to run the desalination from a zero-emission source like solar, wind, hydro, or (please $DIETY, let it be soon) fusion. Of course, once fusion is an option, we're back to fritsd's argument [soylentnews.org] that the CO2 problem is solved at that point anyhow.
Still, I'm happy that desalination is within an order of magnitude for producing the magnesium we'd need; my first reaction to this article was, "who is going to need all that magnesite?" With the prospect of sourcing the raw material from a process we kinda need anyhow, combined with a market for the waste product as building material, there's hope that the economic loop might close and make this a reality. I've seem much worse proposals for methods to save the earth from CO2.
"Space Exploration is not endless circles in low earth orbit." -Buzz Aldrin
(Score: 1, Insightful) by Anonymous Coward on Monday August 20 2018, @08:19PM (1 child)
El Reg used an 11 trillion US gallon figure (about 40 billion tonnes) from NASA and go with that. The NASA number, if you go to the source, is actually the amount of water required to replenish the aquifers to normal levels (not the actual consumption of the state). However, this figure coincidentally turns out to be pretty close to the yearly freshwater usage of the state [usgs.gov]. They use a 7kWh figure per tonne as the energy required by the reverse osmosis process. So that means it will take about 300 TWh to desalinate that 40 billion tonnes. Over the year that's about 35GW.
The total electricity generation of the United States in 2017 [eia.gov] was 4000 TWh. About 65% of that was generated by burning fossil fuels, so the nuclear and renewable portion of that is just 1400 TWh.
So we're talking about about 10% of the entire electrical generation capability of the entire United States, to desalinate the water used by California alone. Or about 50% of the entire country's non-fossil-fuel-burning electrical generation capability, just to desalinate the water used by California alone.
The biggest nuclear plant in the United States [eia.gov] has 3 reactors and has a peak generation of about 4GW. In principle I suppose we could build ten of these in California and use them to run a massive reverse osmosis capability to desalinate that 40 billion tonnes per year. So it appears possible but I doubt it is economical. I think El Reg's conclusion that it is economical is due to their comparison with the state's total energy consumption figure; which includes non-electrical uses and the lion's share of which is transportation (mostly burning fossil fuels... and also that energy is not really in a form usable for desalination purposes), and the assumption that diverting such a massive amount of electrical energy to desalination will have zero impact on prices.
And that's just 1% of the 3 trillion tonnes of saltwater needed to extract the 3 billion tonnes of magnesium to produce 8 billion tonnes of magnesite to sequester the 4 billion tonnes of carbon dioxide from humans breathing alone.
There is a secondary problem. Magnesium is essential for life on Earth. About 70% of the global freshwater usage is in agriculture, and you need to add the magnesium back to the water (you could alternately add it to the soil) after desalination or it's going to eventually kill the crops you irrigate with it. You probably don't need to use all of it, though, as freshwater typically has much lower concentrations than seawater.
Also, it's unclear to me if the reverse osmosis process normally used for desalination can even be used to extract elemental magnesium from seawater, so a different (perhaps more energy hungry) process might be needed.
(Score: 0) by Anonymous Coward on Monday August 20 2018, @09:58PM
Apparently there is just one company ("US Magnesium") remaining in North America producing "primary" magnesium (that is material which is not recovered from existing products). They actually do extract it from water from the Great Salt Lake in Utah (which has a much higher concentration of magnesium than seawater, about 5 parts per thousand) using an electrolytic process.
Unfortunately the US government's annual reports [usgs.gov] do not disclose the US production amounts. It was about 10% of global production in 2008 but China's production has roughly quadrupled since then, and the US production is probably proportionally less.
I can't find a good figure of the total energy usage of the process used but I expect it is quite large as it involves very high temperatures and evaporation of large amounts of water. Apparently they have 300km² of evaporation ponds [usu.edu] which apparently represents the world's single largest industrial use of solar energy (well, at least when that was written a decade ago). Neat eh?
(Score: 2) by fritsd on Tuesday August 21 2018, @03:37PM (1 child)
Magnesium is cheap though:
Once upon a time I was lucky to be on vacation in Bolzano (Nort hItaly).
When I woke up the next morning at dawn, those humongous pink mountains we saw to the north, were the Dolomiti.
Those are made of mostly 50-50 Calcium and Magnesium carbonate AFAIK (I don't believe they coated just the visible outside with the stuff).
(Score: 0) by Anonymous Coward on Tuesday August 21 2018, @10:24PM
The going rate of elemental magnesium, direct from China on eBay, seems to be about 40 USD/kg. I wouldn't call that cheap; it's relatively expensive for a common metal (and one of the most abundant elements on Earth), presumably due in a large part to the high energy cost of extraction [soylentnews.org]—at 0.15 USD / kWh that'd be about 15USD/kg in extraction energy costs alone.
(Score: 2) by fritsd on Tuesday August 21 2018, @05:02PM
Yes that's very true :-) we don't yet know the full cost of *not* decreasing CO2, but this summer vacation I was well pissed off that it was 35°C! And I'm not even a barley stalk! (essential for brewing beer, which you can't drink anymore when it's 35°C anyway. and apparently when it's >=35°C for longer time the barley yield goes down "disastrously")
But this process competes with other Carbon sequestration processes, some of which may be cheaper, is my sincere hope.
I read (a little bit) about biochar: biochar [wikipedia.org]
- plant cheap and fast-growing trees
- let the trees do all the work of the Carbon sequestration as if their lives depend on it, and wait 20 years (repeat every year, of course)
- pyrolyze (i.e. burn but with only the oxidizers of the tree itself, sealed off from air) the wood. This should give enough energy that you only need to set the wood on fire, so it costs little.
- take the gases to burn to heat something else, and drain the tar to make turpentine or something else useful. A large part of the original sequestered CO2 stays in the form of biochar.
- the charcoal can be stuck underground, it improves the soil and gets consumed only very slowly, so it can delay the worst of Climate Change over a period of 1000 years or so.
As long as forest fires are rare this should work? Has anyone done the maths? (Not me).
(Score: 3, Informative) by c0lo on Monday August 20 2018, @11:34AM
Heaps of it, mainly together with Fe, Ca and Al silicates. From which harder to mobilize and extract than from carbonate.
Or... go extract it from Earth mantle [wikipedia.org], I'll cheer from the side.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 3, Insightful) by c0lo on Monday August 20 2018, @10:58AM (2 children)
And the precursor that combines with CO2 is... what exactly?
If the answer is magnesium or magnesium hydroxide, I'll have to tell you the majority of those two substances are obtained from magnesite [wikipedia.org]. With a process that not only releases the CO2 already sequestered, but very likely produces extra amount of CO2 by burning coal.
I can easily take calcined lime to "sequester" CO2 as calcium carbonate... except that the calcined lime is obtained by heating calcium carbonate until it gives away the C02.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 3, Informative) by takyon on Monday August 20 2018, @11:21AM
Everything I wrote was a summary of the research. See reply made to fraxinus above for some ideas about the chemistry.
There is also another source of magnesium compounds I didn't mention.
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 1, Informative) by Anonymous Coward on Monday August 20 2018, @10:25PM
Extracting magnesium from magnesite appears to be very energy intensive. I guess that's because magnesium is so reactive. China produces the lion's share of the world's magnesium using the Pidgeon process (which extracts magnesium from magnesite), and that process requires about 100 kWh / kg of magnesium [uow.edu.au]. If you used diesel to power this you'd need to burn about 8kg of diesel [wikipedia.org] fuel to release the 100kWh to obtain about 1kg of magnesium (assuming you can use 100% of the energy from burning diesel). Burning 8kg of diesel fuel emits about 18kg of carbon dioxide [eia.gov], plus the half kg of CO₂ from the magnesite, let's say 20kg of CO₂ emissions per kg of magnesium produced by this process.
Unfortunately I don't have a figure for the total energy required to extract magnesium from water. That would avoid the problem of releasing already-sequestered carbon from the materials, at least, but I expect the energy requirement is probably on a similar scale.
(Score: 2) by JoeMerchant on Monday August 20 2018, @11:35AM
Scale that down from 72 days to 72 milliseconds, and you've got something that can keep up with industrial CO2 production flows.
72 days means giant ponds like salt drying operations.
🌻🌻 [google.com]
(Score: 1) by anubi on Monday August 20 2018, @11:14AM (3 children)
Wonder if this can be rigged to make concrete as a end product?
If we can't make something useful as an end product, we are certainly going to end up with a shit-load of it.
But, if we can make something that's useful as a paver or building material, at least we will have somewhere to put it.
Else, we gotta plant and maintain more forests... which was how Nature handled this in the first place.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 4, Informative) by takyon on Monday August 20 2018, @11:26AM (1 child)
https://en.wikipedia.org/wiki/Magnesite#Uses [wikipedia.org]
https://www.sciencedirect.com/science/article/pii/B978012803581802378X [sciencedirect.com]
https://cdn-pubs.acs.org/doi/10.1021/acs.chemrev.5b00463 [acs.org]
[SIG] 10/28/2017: Soylent Upgrade v14 [soylentnews.org]
(Score: 2, Insightful) by anubi on Monday August 20 2018, @11:52AM
Those links look interesting... especially the last one.
I wonder how much energy will be required to procure/refine/transform the magnesium, and will we be releasing yet more CO2 to make that energy?
Sometimes, these offerings read like the ads which goad me to buy this "thing" and "Save $20"! ( When the "thing" is priced at $200 ).
Geez, I'll go broke with all the savings!
I consider I "save" at least $180, ( probably more like $500 , by the time all the businesstalk* hidden in the ad is honored ) by just walking away.
*Other charges may apply. Batteries not included. Just pay separate fee.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 3, Interesting) by zocalo on Monday August 20 2018, @11:59AM
UNIX? They're not even circumcised! Savages!
(Score: 1, Informative) by Anonymous Coward on Monday August 20 2018, @02:24PM (3 children)
Sorry, you're not even going to make the slightest dent in atmospheric CO₂ levels with these kind of quantities.
A typical human breathes out about 1kg of CO₂ per day, which is about half a tonne per year. That's your carbon footprint just by being alive. (If you also include other aspects of a person's carbon footprint, a typical westerner is about 30–40 times that).
With ~8 billion humans that's ~4 billion tonnes of CO₂ per year, just by those people being alive. So just to counteract the carbon footprint of humans breathing you need to produce 8 billion tonnes of this shit every single year (at increasing quantities year over year), and you need to do it all with zero carbon emissions in your entire production, transportation and storage process.
Sorry, while this might be a cool process for manufacturing magnesite; the application as a solution for atmospheric CO₂ levels sounds like bullshit to me.
(Score: 1, Interesting) by Anonymous Coward on Monday August 20 2018, @02:36PM
To get an idea of how ridiculous this quantity is, it is interesting to compare this number with the global production of magnesium today, which is about 800 thousand tonnes per year!
(Score: 0) by Anonymous Coward on Monday August 20 2018, @02:48PM
I love this tidbit from the article (link is original):
If you follow the link, the actual number in the source article is 40 billion tonnes per year.
But hey, what's a few orders of magnitude between friends?
(Score: 1, Interesting) by Anonymous Coward on Monday August 20 2018, @06:46PM
Moreover, considering just the carbon and estimating by standard atomic weights, magnesite (MgCO₃) is about one seventh carbon by mass.
Glucose (C₆H₁₂O₆), is a bit less than half carbon by mass. So corn syrup (essentially pure glucose) has about 3 times the carbon content as magnesite for a given mass.
Given that, the photosynthesis reaction seems like a much more effective sequestering process:
6CO₂ + 6H₂O -> C₆H₁₂O₆ + 6O₂
The reason is that less of the (more massive) oxygen remains, and the resulting O₂ is not a greenhouse gas so we don't need to sequester it.
(Score: 5, Informative) by Runaway1956 on Monday August 20 2018, @02:33PM (11 children)
The problem with portland cement is less that it is energy intensive, than it is short lived and wasteful. The typical concrete highway has to be torn up and replaced every decade or so, because it has been beaten to death. (The two primary causes of this are spalling and rust of the rebar, and roadways being undercut by the elements.) Concrete in most structures lasts considerably longer, if maintenanced properly. But, concrete in many industrial settings doesn't last so well. I've built concrete structures that have lasted thirty years and more. I've also built concrete structures that were replaced in about 20 years.
Spalling is a big deal in concrete. Roman concrete didn't spall. A good deal of their concrete still stands, today. Notable are their harbor breakwaters. The concrete crystallized, and got stronger, in the presence of seawater, instead of deteriorating, like our modern-day Portland.
We need to figure out the Roman's recipe. That way, we can build once, and count on the structure being there a hundred years, or five hundred years in the future.
Now, let's be clear - our concrete falls down in less than a century with intensive maintenance. Roman concrete is still standing today, without ANY maintenance over the course of a couple millennia.
http://www.romanconcrete.com/ [romanconcrete.com]
Simply rediscovering the recipe for Roman concrete would reduce our need for concrete by orders of magnitude. If concrete highways would last for only 50 years, instead of a single decade, the highway departments would see an 80% reduction in the need for concrete. Concrete bridges, ditto. Dams and reservoirs, and so much more. And, buildings.
My high school was torn down soon after it's 100th anniversary. The concrete was rotten, and the mortar holding the bricks had been replaced several times. With Roman concrete, the school likely would have seen more than 200 years of service, and possibly 500 years. Or longer.
(Score: 0) by Anonymous Coward on Monday August 20 2018, @03:49PM (3 children)
You make it sound like there was one recipe for Roman concrete, but according to https://en.wikipedia.org/wiki/Roman_concrete [wikipedia.org] there are wide variations depending on the availability of local material.
(Score: 2) by Runaway1956 on Monday August 20 2018, @04:40PM (2 children)
That's all well and good: Portland cement and it's concrete have a lot of variations. I've poured with added air, with fiberglass, with fly ash, with oversize rock, with pea gravel. I can't say just how much the recipe for Portland varies, but I can say with certainty that not every bag of Portland I've ever handled was precisely the same.
The thing about Roman cement is, at least some of it has lasted 2000 years. THAT is what we need! And, the secret seems to be in the volcanic ash they used. Our fly ash is a poor substitute for the volcanic ash they used.
(Score: 0) by Anonymous Coward on Monday August 20 2018, @11:56PM
https://www.geopolymer.org/archaeology/roman-cement/high-performance-roman-cement-and-concrete-high-durable-buildings/ [geopolymer.org]
(Score: 2) by deimtee on Tuesday August 21 2018, @11:31AM
Other than the fly ash, the big differences are water content when molding, and time to set. Roman concrete is barely damp, and is pounded into place - add some, tamp it down hard, add a bit more, tamp it down hard, etc. Then leave it alone.
It takes weeks to set to the point of being slightly usable, and months to years to set properly.
The water used to set modern concrete leaves voids, which is why it deteriorates so fast. Water and air can percolate through to the rebar, causing rust, and water in the voids can freeze, causing spalling.
If you cough while drinking cheap red wine it really cleans out your sinuses.
(Score: 3, Interesting) by VLM on Tuesday August 21 2018, @01:53AM (6 children)
From a strictly historical perspective the Romans saw their infrastructure as a mix of a welfare/jobs program and a propaganda outlet. Like if the USA delivered postal mail with Saturn-5 rockets we wouldn't be doing it to be environmentalist or economically efficient.
We could build a 10000 year concrete bridge or whatever, but it would be a heck of a lot cheaper to build a 100 year bridge 100 times.
And some very powerful people would be very pissed off.
Some epic stories from China in the last decade or so about crumbling concrete.
Just making the point that merely being able to make 1000 year concrete doesn't mean anyone will or will want to. No actual disagreement.
(Score: 2) by Runaway1956 on Tuesday August 21 2018, @02:09AM (5 children)
You say that like it might be a bad thing?
More seriously - I suspect that a lot of environmentalists don't have clue one about the production of concrete, or the alternatives to Portland. If they did, there would probably be more high profile protests at construction sites around the nation, or even around the world.
Adobe, for instance, is far more environmentally friendly than concrete, and it can be very durable. People have been using adobe since prehistory. But, we don't see major corporations dealing in adobe. It would be anathema to produce cheap, eco-friendly, durable building materials to the masses. It's much more profitable to provide concrete foundations, and cut down pine plantations to make homes with.
(Score: 2) by VLM on Tuesday August 21 2018, @08:22PM (4 children)
The masses are kinda limited to Nevada, in that it doesn't work below grade, where it rains, there there's intense freeze/thaw cycles, where there's earthquakes; still millions of people could use adobe in theory.
I suspect mass adobe use would suffer even worse from corruption and poor installation than cement. Lots of building collapses.
Cement is some pretty nasty stuff WRT environmental cost; makes it all the worse when its wasted via bad short lived design. If you're gonna "destroy the planet" by making the cement for concrete for a road, at least design the road to last longer than 20 years, etc.
(Score: 0) by Anonymous Coward on Tuesday August 21 2018, @10:38PM (3 children)
How many road surfaces in the world are actually made with portland cement, though? Does it represent a significant amount of portland cement use globally?
Most road surfaces are made with asphalt concrete, which uses bitumen (essentially the shit left over when you've finished extracting all the other useful compounds out of crude oil) as a binder. Incidentally it is also one of the most recyclable materials in use today: basically all of the bitumen can be recovered from an old road surface by heating it.
(Score: 2) by Runaway1956 on Wednesday August 22 2018, @01:25AM (2 children)
Can't speak for any other countries, but a lot of the US highways and interstate highways are concrete. Some lesser roadways, such as city streets, as well. Oftentimes, you don't see the concrete - roadways with a lot of wear on them are often resurfaced with asphalt.
https://pubs.usgs.gov/fs/2006/3127/2006-3127.pdf [usgs.gov]
(Score: 0) by Anonymous Coward on Wednesday August 22 2018, @01:53PM (1 child)
So what you're saying that for roads in the US, even if they were originally surfaced with portland cement concrete, when surface repairs are needed those repairs are often done using asphalt concrete. In other words, portland cement is typically not used for resurfacing work.
So there is 48 million tonnes of cement currently in place in US interstates, in total. That's about 1% of global production of cement which is about 4 billion tonnes per year. And it sounds like that cement is mostly from the original construction if repairs are done with asphalt... roads aren't looking like a major consumer of cement in the world.
(Score: 2) by Runaway1956 on Wednesday August 22 2018, @02:29PM
Need some clarity, I guess.
Typically, an Interstate Highway was built of concrete. After a few years use, the surface would be "profiled", that is, a big old machine would come along, and grind up the top 1/2 inch or so. A few more years use, and they put a layer of asphalt on top of the already profiled surface. Relatively quickly, the asphalt wears down - two or three years, and it's ready to be replaced. The DOT might pull that old asphalt up, or they might surface over top of it again with more asphalt. Of course, all these years, they are watching the edges of the concrete, watching for erosion, and scanning the roadway with X-rays. Nowadays, they use GPS-like satellite data, so they can see more clearly which slabs might be moving, horizontally or vertically. At SOME POINT, the DOT makes up their mind that the roadbed is no longer serviceable.
They come out, pull up all the asphalt to be recycled, then start breaking up the concrete, and hauling that off to be recycled. Strip the roadbed, reinstall drainage, rebuild the roadbed on top of that, then pour another "superslab".
I leave it to you to find out how long the "typical" slab of concrete lasts. I grew up in Pennsylvania. There was an awful lot of news during my junior and senior high days about fraud. Highways that were expected to last for 20 years and more were being torn up and replaced when I was a teen. (A bit of context - Interstate 80 was being laid down when I was born.)
Now, SOME of those problems were technical. Sharon Pa. was kinda infamous for being near impossible to build across. Apparently, they worked for months to build their stabilized roadbed across the swamp. The bed finally passed inspection, and the crews went home for the night, expecting to start forming the next morning. Problem was - next morning, the roadbed and all the equipment sitting on it had sunk out of sight, into the swamp!
But, there was a helluva lot of fraud involved, as well. Areas further up in the mountains, built on bedrock, were falling apart as well, because the contractors used low-grade mixes, and the inspectors let them get away with it. Profit, profit, profit!!
If the roads are built to the highest standards, you might expect the concrete to last 30 or 40 years. If the standards slip, 20 years is unlikely.
Generally, if you're driving on a major highway in the US, you are probably riding on or above a concrete slab. If you're seeing macadam or some other surface, that surface is just dressing on top of the concrete.
Tertiary roads may or may not have concrete under them. State highway 41, in front of my house, has none. Stabilized earth, pretty good drainage, and about three or four inches of blacktop. When the road needs resurfacing, it gets a chip&tar treatment. Towns and cities pretty much do whatever they want to do, or what their budget allows.
(Score: 0) by Anonymous Coward on Monday August 20 2018, @04:48PM
Not in any meaningful scale
(Score: 1, Funny) by Anonymous Coward on Monday August 20 2018, @10:45PM
We already know how to store carbon. Trees are pretty good at it, require no advanced chemistry and virtually no maintenance. Notably wind moves CO2 away from power plants, to forests without any shipping expense whatsoever. CO2 sequestration is a question of capacity, not method.
Notably the other big issue is not the CO2 but all the other toxic chemicals and unburned fuel that come out of a typical coal fired plant. If you've ever been near a really big coal plant, you'll know what I'm talking about. Everything you touch for miles around it, has a film of coal sludge on it. Even the air feels oily all the time. That is why they've been switching to cogeneration.
Most plants will increase their growth rate up to 30% with CO2 enrichment. So the practical question is, why don't all power plants have massive greenhouses next to them, producing millions of seedlings a year? Considering the incredible cost of adirondack and sitka spruce, flamed maple, and white oak, and the respective industries that are utterly crippled because of the rarity of those materials (ship building, aircraft construction, insrument making, cooperage etc.) one would think the answer would be obvious.
But I guess a whiz bang rock making plant sounds pretty cool. God knows we could use more rocks. Hit em' with a stick to make music? Nope. Store beer in them? Not unless your Irish. Fix a leak in your boat? Nope. Make a wing for your new airplaine? Certainly not. Screw up the PH in all your rivers and streams because rainwater runnoff now has carbonic acid in it? Yep.
I can see what they mean. Rocks are awesome.
(Score: 0) by Anonymous Coward on Monday August 20 2018, @11:50PM
This is an awful idea. There are already serious magnesium deficiencies in the soil of many countries[1]. We do not want to sequester magnesium, it is making people sick and stupid... I swear these "climate engineering" ideas are straight out of idiocracy. Its like they cant consider more than one thing at a time.
[1] https://www.sciencedirect.com/science/article/pii/S221451411500121X [sciencedirect.com]