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Schroder
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PostTue Sep 24, 2019 5:32 pm 
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Bernardo wrote:
Where in the concrete process does the CO2 get expelled?

Lime rock has to go through a kiln and it uses typically natural gas as fuel. When you drive by a cement plant the kiln is the long horizontal turning cylinder with a stack at the end where all the emissions originate. Not to mention what is used to do the mining.
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Malachai Constant
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PostTue Sep 24, 2019 6:01 pm 
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In Portland Cement limestone CaCO3 is “burnt” heated to produce CO2 and lime CaO. When the limestone “sets” CO2 is reabsorbed from the air into the lime the only loss is the carbon in the fuel used to burn the lime.

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Pyrites
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PostTue Sep 24, 2019 6:21 pm 
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CO2 is released as inherent part of process of calcination of limestone. This produces the core active component of concrete.

Lonestar used to have a rotary kiln south of the ports in Seattle. Big pipe looking thing raised above head level, on a slight angle.

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Bernardo
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PostTue Sep 24, 2019 7:35 pm 
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I knew a few folks here would have some technical knowledge of this.

Would it be very expensive to capture the emissions from the burning fuel?  There's probably a lot of room for improvement there.  I guess I'm wondering if the comparison with concrete is really based on optimized concrete production?
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Sculpin
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PostWed Sep 25, 2019 7:19 am 
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Jake Neiffer wrote:
A forests capacity to sequester carbon is optimized if the trees are healthy and at an appropriate stand density.  This may require cutting trees to accomplish.

Healthy sure, but stand density?  Carbon is sequestered by sunlight striking leaves.  Even in the worst doghair stands, nearly all the sunlight is captured by needles and leaves.  Can you back up your assertion about stand density affecting carbon sequestration?   confused.gif

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Jake Neiffer
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PostWed Sep 25, 2019 7:43 am 
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True, but doghair stands are stressed and growth will eventually be limited.  Also more susceptible to being nuked in a fire.

Here is one example discussing these matters.  https://www.sciencemag.org/news/2017/04/save-forests-cut-some-trees-down-scientists-say
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NacMacFeegle
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PostWed Sep 25, 2019 8:39 am 
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I've got no problem with thinning the unnaturally dense replanted forests of the Pacific Northwest. I also wonder if there have been any studies done looking into how forest diversity affects carbon storage rates and potentials. In a diverse natural forest you get many species filling out the various layers of the forest, while in a commercial, monocultural forest they use herbicides to kill practically everything save for the species of tree they are growing. I would think that the more diverse and healthy the forest the greater the rate/potential for carbon storage would be.

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Pyrites
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PostWed Sep 25, 2019 8:34 pm 
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Stefan wrote:
the building probably is built out of wood because it will cost less.  probably has nothing to do with desire for carbon footprint.

I’ve been following this for maybe five years. Carbon sequestration and renewable resources are flags waved. One London architects even passes out Doug-fit seeds as part of his pitch.

Flexibility of design. Speed of off-site reductions in schedule and labor hours. Foundation methodology the same, except maybe 1/4 as much mass supported, restrained. Much less on site time, after foundation work, again, with much less labor. Time is not just paying interest on money borrowed or revenue lost. It’s also market risk. Condos may be selling like sushi one quarter, stink the next.

I think convergence of motivations, maybe.


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Pyrites
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PostWed Sep 25, 2019 8:39 pm 
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For WA & OR States I think motivation is supporting local industry.

One recently opened plant in eastern WA.

https://m.facebook.com/vaagentimbers/


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