Storing carbon dioxide in cement.
Nato Welton
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Making cement for concrete involves heating pulverized limestone, clay, and sand to 1,450 °C with a fuel such as coal or natural gas. The process generates a lot of carbon dioxide: making one metric ton of commonly used Portland cement releases 650 to 920 kilograms of it. The 2.8 billion metric tons of cement produced worldwide in 2009 contributed about 5 percent of all carbon dioxide emissions. Nikolaos Vlasopoulos, chief scientist at London-based startup Novacem, is trying to eliminate those emissions with a cement that absorbs more carbon dioxide than is released during its manufacture. It locks away as much as 100 kilograms of the greenhouse gas per ton.
Vlasopoulos discovered the recipe for Novacem's cement as a grad student at Imperial College London. "I was investigating cements produced by mixing magnesium oxides with Portland cement," he says. But when he added water to the magnesium compounds without any Portland in the mix, he found he could still make a solid-setting cement that didn't rely on carbon-rich limestone. And as it hardened, atmospheric carbon dioxide reacted with the magnesium to make carbonates that strengthened the cement while trapping the gas. Novacem is now refining the formula so that the product's mechanical performance will equal that of Portland cement. That work, says Vlasopoulos, should be done "within a year."
Other startups are also trying to reduce cement's carbon footprint, including Calera in Los Gatos, CA, which has received about $50 million in venture investment. However, Calera's cements are currently intended to be additives to Portland cement rather than a replacement like Novacem's, says Franz-Josef Ulm, director of the Concrete Sustainability Hub at MIT. Novacem could thus have the edge in reducing emissions, but all the startups face the challenge of scaling their technology up to industrial levels. Still, Ulm says, this doesn't mean a company must displace billions of tons of Portland cement to be successful; it can begin by exploiting niche areas in specialized construction. If Novacem can produce 500,000 tons a year, Vlasopoulos believes, it can match the price of Portland cement.
Even getting that far will be tough. "They are introducing a very new material to a very conservative industry," says Hamlin Jennings, a professor in the Department of Civil and Environmental Engineering at Northwestern University. "There will be questions." Novacem will start trying to persuade the industry by working with Laing O'Rourke, the largest privately owned construction company in the U.K. In 2011, with $1.5 million in cash from the Royal Society and others, Novacem is scheduled to begin building a new pilot plant to make its newly formulated cement.
clearly the facts are not an issue for this publication any more. otherwise, there would be some acknowledgement that there is no proven link between human activity and climate change, making the entire article moot.
In reading the article carefully it explains why this process produces much less CO2 or even consumes CO2: this process DOES NOT USE LIMESTONE LIKE TYPICAL CONCRETE PROCESSES. From the article: "by mixing magnesium oxides with Portland cement." he says. But when he added water to the magnesium compounds without any Portland in the mix, he found he could still make a solid-setting cement that didn't rely on carbon-rich limestone". In other words, the mix is made with magnesium compounds and it does end up having carbonates as a result of atmospheric absorption of CO2. I hope that helps,
BlahBlizah - suggest you Read b4 you rant dude. The 650-920 kg of CO2 emissions are associated with trad portland cement.
Story says the Novacem concrete locks away 100kg of CO2. Having said that it would be good to know if this is net saving or not???
The article DOES say: "Novacem, is trying to eliminate those emissions with a cement that absorbs more carbon dioxide than is released during its manufacture." However, I do agree, it would be nice to see the total energy balance with quantitiative figures so we don't have to guess the process and then do the thermo calcs on our own!
The article reads like the hypey corn based ethanol articles I've seen over the years. All politi-hype for the deceived politically correct hoi polloi, NO Technical HEFT!!! Doesn't anyone do or know how to do a comprehensive energy balance any more?
The PopSCi comment is appropos. They do a sort of hyped "science lite" for those of us looking for some depth and detail in our tech info and I've been a subscriber since my Dad got me my first subscription some 45 years ago! Good place to start but most certainly not where you want to end!
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Decarbonating MgCO3 or CaCO3 is just the same for the CO2 release.
It could only be advantageous if:
· MgO would come from another mineral source than a carbonate: e.g., brucite (Mg(OH)2), talc, rock salt, or;
· if the melting temperature of the final mix in the cement oven would be much lower than 1450 °C, decreasing so the use of fossil fuel needed to make the cement.
If it is not the case, it is difficult to distinguish the benefit of the technique.
Seems to be a kind of perpetual motion but with the CO2 cycle: where is the benefit ? I am sceptic. No other argument favourable to the technique ? Fata morgana or propaganda from cement producers ? Sounds like green banking.
Anyway, a physical limit would be the source of Mg raw materials necessary to make billions tons of Mg-based cement. No idea also on the long-term durability of such a concrete: Mg(OH)2 (brucite) is also an expansive material and delayed crystallisation could have unexpected effects.
Carbonate are not good CO2 getters.
The only real CO2 sinks for mineral trapping are olivine (Fe,Mg)2SiO4 and alkaline basaltic minerals.
What about biomimicry for the production of clinker and lime ? Are high temperatures and kilns crucial ?
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These companies are very adept at securing investment funds for work that others have spent much R&D on for years. People like Judd Hamilton with ceramic cement, Bindan corporation, Argonne national labs, Washington State university, & many others have spent years developing low carbon foot print, carbon sequestering, mix designs. The main problem so far has been that portland cement is still much cheaper than the lower carbon alternatives that are already in existence.
Guest (mongander)
I remember from flying magnesium skinned choppers in the Marines that the magnesium degrades when exposed to salty ocean air. Magnesium is also highly flammable.
We're talking about magnesium salts here, not metallic magnesium.
Look at Fundamental - Why Cement
http://blog.163.com/solvere@yeah
Cement is water, energy, clean water intensive.
During production, immense heat is needed, CO2 is also produced.
During curing, immense clean water is needed, immense heat and CO2 are released.
Energy, Clean Water are precious.
Cement is not the only material for construction, we must minimize the use of cement.
We must design building holistically. If they are not structural element, we can use agro-waste fibre, etc for partition wall, facade wall, ceiling board, even floor board. That leave only beam and column that need steel, concrete. A patent "Expand Exposure, Full Concealment" provide details how to further simplify building design, to expand the harnessing of energy from environment, concealed against the unsightly fully.
It is through this holistic way, we reduce energy, clean water, CO2 emission drastically.
While construction becomes a simpler, lighter, easier, faster, weather independent process like Ikea kits.
This is briefed in "Post Industrialization Dynamos" ISBN 9810 833558 and will be detailed in
"The Gold - beyond green and eco" ISBN 9810 845407
This sharing is not to promote the invention, but to promote our thoughts into deeper, more comprehensive understanding of the immense order of nature to fill the insatiable nature of man.
Re: Look at Fundamental - Why Cement
@David: well put! it's just another 18th cent. process who refused to die up to now! when we learn how to mimic photosynthesis (25 years at most, 10 before full production kicks in, and the sun will bless us with an oxygen bonanza and furnish us with unbelievable amounts of bio-mass to be cleanly digested for production of heat, electricity, clean water and neutral mineral solid products which will be used as non-toxic
wall materials... we just have to refuse to think in terms of the past, and be weighted down with all the old ways, and their inefficiency, which have been "our Old Way" for so much of the time. But then , as history teaches us, we only do that
when we are in the jaws of the Dragon... and we let loose the four Horsemen on Earth. And then, reeling and bleeding from our wounds, we try to mend our ways for a little while, before greed pulls us back to the brink... We always learn something, and then quickly forget what it was!
But this was written long before any of us were born:
"We cannot prove that those are in error who tell us that society has reached a turning point; that we have seen our best days. But so said all before us, and with just as much apparent reason. On what principle is it that, when we see nothing but improvement behind us, we are to expect nothing but deterioration before us?"
Re: Look at Fundamental - Why Cement
("During curing, immense clean water is needed, immense heat and CO2 are released")
Water and heat, yes, but during curing of common Portland cement, CO2 is ABSORBED from the atmosphere over a long period of time.
As the CO2 absorbs into cement, the carbonate front migrates inward. When it reaches the rebar, the rebar rusts.....lessons learned from Biosphere 2.
Those against the use of concrete in building construction are forgetting its primary advantage: fire resistance. The concrete floor of your hotel room contains fire between floors, allowing additional time for escape. The concrete columns of your hotel resist the damaging effects of fire's intense heat, preventing (or at least delaying) catastrophic collapse.
The reason concrete, and gypsum products for that matter, are so effective at fire resistance is because they contain so much water.
In a country clamoring for increased population density (no more sprawl), I suspect the use of products with "natural" fire resistance, such as concrete, will only increase.
One of Novacem's critical hurdles will be demonstrating their product's fire resistance.
Fire Resist of Bio-waste board - an important, profitable field
Yes, we agreed Fire Resist is one key advantage why concrete, cements are used.
But if you examine post earth quake scence, people are not killed by earth quake, but kill by bricks and mortar.
Also urban rejuvenation, post disaster reconstruction, broken mortar is difficult to remove, worst if reinforced by re-bar.
If you look at how Japan design their buildings to stand the earth quake, then you see walls, floors are not constructed of concrete. Even pillars are mostly steel (coated with concrete for fire proving).
The need to replace concreate, is not just of reducing energy, carbon, clean water usage. Also it is overweight, under strength, costly to tear down, yet fallen like dominos when earthquake come.
Fire proving bio-fibre is already done, by coating fireproofing coats or heat spreading conductor (this is used in power cables in critical applications). This is an infinite field for R&D. If these two methods are still inadequate, then watch out for another new invetnion from here.
Solvere
www.cts-ideas.com
In reference to the amount of carbon removed,
here's the company website that describes the
process and how they plan for it to be a carbon-negative process (vs. 600+ kg carbon):
http://novacem.com/technology/novacem-technology/
That said, I'm more with 'smithsomian' in thought that there's been no convincing scientific link between human activity and climate change. I watched a congressional hearing recently with a panel of scientists pandering to politicians - lots of strong emotional arguments, light on the science. I don't remember hearing one quantitative prediction except the end of the one world we live on. I'm concerned it's become more of a religion.
As for your comment about anthropogenic climate change - there are buckets of compelling studies out there showing very strong links between human activities and climate change. Go read the literature. It is easy to find. Start with the IPCC reports. Or Nat Geo and Smithsonian. There are some things that aren't well-understood, but that is the nature of science in general. While gravitation is still a theory, it is pretty well understood that if I drop a pencil, it will hit the floor. We also don't understand how to keep oil from gushing into the Gulf of Mexico (BP incident) but that doesn't keep us from drilling. So it is irresponsible to simply state that we should not take action despite the preponderance of evidence just because you don't believe it. Besides, like I tell my kids, there are few bad reasons to conserve, but many good reasons.
Very Good Joe. I was wondering if someone on this forum was going to state the obvious.It is unfettered foolishness to dismiss a solvable problem simply because it is easier to say there isn't evidence to consider. This outlandish stance that there is no hard evidence that Human interaction effects our biosphere is as absurd as saying there is no such thing as fire because I am not burning.
The big question concerning "Green" concrete is whether or not the process can be altered to meet environmental needs and our building requirements. There seems to be some evidence that it can but not without a radical shift or approach and prioritization.
too much co2 concentration IN concrete? I am not chemist but could this be another cancer provoking mean? I hope not.
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erbium
336 Comments
This is interesting
I've wondered if sort fibers of various lengths could reinforce concrete. Currently it is the crystals when it sets that provide strength.
Fiberglass is very strong, and carbon fibers are similar. If these were made from flue gas then added to concrete would sequester quite a bit of carbon. Since carbon fibers would have free reactive bond sites would have to figure out if reactions that would occur down the road in use would strengthen or weaken the concrete made with carbon fibers.
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shatuga
17 Comments
Re: This is interesting
Fiber-reinforced concrete is in common use in the industry, to add strength, resist cracking, and confer other smoothing properties to concrete mixes.
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