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>concrete Concrete is staggeringly carbon-intensive. You need to burn a lot of fuel to produce cement, which itself emits carbon during the calcination process

>concrete Concrete is staggeringly carbon-intensive. You need to burn a lot of fuel to produce cement, which itself emits carbon during the calcination process. Every ton of cement produces about 900kg of CO2, making up about 5% of global carbon emissions. http://blogs.ei.columbia.edu/2012/05/09/emissions-from-the-cement-industry/ http://blogs.ei.columbia.edu/2012/05/09/emissions-from-the-c...

sunstone 9y ago
If you do some quick and dirty calculations of a 3000 sqft concrete house with 5 people lasting 100 years then the CO2 burden comes out to around 43kg/yr/person. An average american produces about 1000kg/yr so that's around 5% of a person's total CO2.
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- jotm 9y ago
  Ha, and they're living in some shabby plywood houses, at that.
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Turing_Machine 9y ago
> You need to burn a lot of fuel to produce cement, which itself emits carbon during the calcination process. The CO2 emitted by the calcination process is reabsorbed when the Portland cement sets. You won't get back the CO2 expended in the heating process, but the calcination itself is more or less CO2-neutral. It's roughly this: Making cement: CaCO3 (limestone) + (some other stuff, varying with the type of cement) + lots of heat -> CaO + CO2. Setting cement: CaO + H2O -> Ca(OH)2 ("portlandite"). Ca(OH)2 + CO2 (from atmosphere) -> CaCO3 + H20 (chemically much the same as the original limestone, but now set into a useful form). I'm too lazy to balance all the equations, and there are a lot of other things mixed into modern cements, but that's the basic idea. It seems unfair to charge cement with the CO2 driven off during manufacture, while ignoring the fact that an equal amount of CO2 is absorbed during setting.
anfilt 9y ago
I did say if we get a handle on the energy that fixes a lot of things. If that furnace was powered by a CO2 free source the chemical reaction is neutral once the concrete is used.

sunstone 9y ago

If you do some quick and dirty calculations of a 3000 sqft concrete house with 5 people lasting 100 years then the CO2 burden comes out to around 43kg/yr/person. An average american produces about 1000kg/yr so that's around 5% of a person's total CO2.

deleted 9y ago
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jotm 9y ago
Ha, and they're living in some shabby plywood houses, at that.

deleted 9y ago

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Turing_Machine 9y ago

> You need to burn a lot of fuel to produce cement, which itself emits carbon during the calcination process. The CO2 emitted by the calcination process is reabsorbed when the Portland cement sets. You won't get back the CO2 expended in the heating process, but the calcination itself is more or less CO2-neutral. It's roughly this: Making cement: CaCO3 (limestone) + (some other stuff, varying with the type of cement) + lots of heat -> CaO + CO2. Setting cement: CaO + H2O -> Ca(OH)2 ("portlandite"). Ca(OH)2 + CO2 (from atmosphere) -> CaCO3 + H20 (chemically much the same as the original limestone, but now set into a useful form). I'm too lazy to balance all the equations, and there are a lot of other things mixed into modern cements, but that's the basic idea. It seems unfair to charge cement with the CO2 driven off during manufacture, while ignoring the fact that an equal amount of CO2 is absorbed during setting.

anfilt 9y ago

I did say if we get a handle on the energy that fixes a lot of things. If that furnace was powered by a CO2 free source the chemical reaction is neutral once the concrete is used.