cement is the world’s leading construction material — but did you know producing it is one of the major sources of greenhouse gas emissions accounting for about 8 percent of all such releases? this means that if cement production were a country, it would be the world’s third-largest emitter. aiming to solve this problem, a team of researches at MIT has come up with a new way of manufacturing emission-free cement that could eliminate the total emissions while also making other useful products in the process.
in a demonstration of the basic chemical reactions used in the new process, electrolysis takes place in neutral water. dyes show how acid (pink) and base (purple) are produced at the positive and negative electrodes. a variation of this process can be used to convert calcium carbonate (CaCO3) into calcium hydroxide (Ca(OH)2), which can then be used to make portland cement without producing any greenhouse gas emissions. cement production currently causes 8 percent of global carbon emissions.
image by felice frankel
‘about 1 kilogram of carbon dioxide is released for every kilogram of cement made today,’ comments yet-ming chiang the kyocera professor of materials science and engineering at MIT. ‘that adds up to 3 to 4 gigatons (billions of tons) of cement, and of carbon dioxide emissions, produced annually today, and that amount is projected to grow. the number of buildings worldwide is expected to double by 2060, which is equivalent to “building one new new york city every 30 days,’ he says. and the commodity is now very cheap to produce: it costs only about 13 cents per kilogram, which he says makes it cheaper than bottled water.
time-lapse video of the decarbonation cell containing pH indicator dye. this decarbonation cell starts at pH 6, as indicated by the yellow color, and has no separators. calcium carbonate powder has been placed at the bottom of the left chamber.
cement is made by grinding limestone and then cooking it with sand and clay at high heat, which is produced by burning coal. this process generates carbon dioxide from the burning of the coal and from the gases released from the limestone. the new process created by chiang would eliminate or drastically reduce the emissions by first, eliminating fossil fuels from the heating process by exchanging them with clean, renewable energy. then, it would use an electrolyzer to dissolve the limestone.
time-lapse video of the decarbonation cell containing pH indicator dye. porous paper separators have been placed in front of each electrode. B, and CaCO3 powder in a cup surrounding the OER electrode on the left.
‘in their laboratory demonstration, the team carried out the key electrochemical steps required, producing lime from the calcium carbonate, but on a small scale,’ reports MIT news. ‘the process looks a bit like shaking a snow-globe, as it produces a flurry of suspended white particles inside the glass container as the lime precipitates out of the solution.’
project info:
name: emissions-free cement
developed by: researchers at MIT
MIT MEDIA LAB(49)
Feb 14, 2020
Sep 03, 2019
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Mar 29, 2019PRODUCT LIBRARY
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Emission free cement…!!!
That is clearly hype and advertising…not honest science!!!
First, I would really love to know the primary funding source for this research and information. It wouldn’t be the “cement industry” itself would it?
Second, starting an article with cherry picked and groomed statistics is always a red flag from my perspective. OPC (ordinary portland cement) is the world’s construction industry addiction…not a great building material. Yet down playing its emissions to only 8% is clearly a groomed statistic and not taking into account all the other support industries that are involved in its harvesting, transportation, fabrication, and manufacture …as well as…its continued replacement as the OPC infrastructure of the world falls apart around us about every 20 to 40 years only to be replaced with the same crap product…MODERN OPC.. Which is great for the cement and construction industry behind it for sure…So to be honest, let’s use the real stats on what it does to the level of pollution generated across the board from the complete picture of its use (and re-use) at 25%…not 8%.
As to a “new way,” I find these comments amusing when I read them. Most often it is more about “reinventing the wheel” than a “new way.” A wheel, by the way, that wasn’t broken in the first place and functioned perfectly (and better than today) for the first four thousand years of its existence. Humans had geopolymeric methods we are still trying to “re-learn” and related pozzolans (aka natural cements) far superior to modern day OPC, but the greedy could not really build a “super industry” around those modalities so it got “dumbed down” and industrialies to be a major consumable and also profitable…NOT…a better building material. So this may be a “new way” (perhaps?) at making a crappy building material easier to make, but why do it when the original materials have proven over millennia to be better and there are alternatives to it anyway?