Discussion in 'Chemistry' started by kwhilborn, Apr 11, 2007.
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By locking up CO2 in the pulp.
Paper is made from fast growing trees.
Instead of recycling? No.
Recycling newspapers doesn't turn their carbon into CO2.
Fast growing trees could be used to sequester CO2 I guess, but you might as well just bury/store the trees directly rather than turning them into paper first, right?
Is recycling better than sequestering?
Possibly not if you want to lower the level of CO2.
Just throwing an idea in the air. Not sure.
If you burn it it will go back to CO2, plus contaminants.
If you recycle it, it will prevent new trees being grown to replace it.
You could tie the laws into the paper industry.
If all the paper pulp had to be sequestered, say sent as sludge into empty oil wells, then the cost of paper would have to include the cost of disposing of it.
We waste a lot of paper.
You can compost paper and add it to soil, which adds to the carbon in said soil. If you combine that with no-till agriculture, then you start getting carbon depositing in the soil. So recycle the paper until it's not re-usable, then compost it.
I posted an link a while ago about cement that is actually carbon-positive...as in it's production takes more carbon out of the air than it puts in.
Considering that regular cement production is basically one pound of cement=1 pound of CO2 in the air...I hope the new cement catches on in a large way.
Good point Chimpkin.
Yes. Compost paper rather than sequester it.
Storage as soil is an even better idea than sequestering it.
We need to think of methods of removing CO2 from the atmosphere, and that is an excellent one.
Not sure why you think recycling is better than soil creation.
And what were your ideas about cement?
They sound worth repeating.
Oh, I figured we'd recycle the paper until it was unable to be recycled, THEN compost it...
as far as the cement:
(I thought it was pound for pound, one pound of cement created=1 pound of emissions:shrugPlease Register or Log in to view the hidden image!
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If you can give link again, please do so.
I think typical cement production is via slightly-tilted long tube with natural gas flame inside the tube heating the ground up ore mix - to drive water of hydration out, I think.
Brazil has lot of cheap heavy oil and relatively little natural gas. When I added water to make wet cement, there often was a blackish oil film floating on the surface. I assumed from these facts that heavy oil flame is often used in Brazil's cement production.
I guess the de-hydration heat could be supplied electrically, but that would not be "carbon neutral" in US, but might be close to it in Brazil as ~90% of Brazil's electric energy is either hydro-power or ~ 5% generated from burning crushed sugar cane stocks. That is not done as electrical energy is more valuable than same heat energy.
Except for non- fossil fuel heating, how is the water of hydration removed and yet "carbon neutral"? That sounds impossible to me - so I am very interested to know how someone is claiming to make "carbon negative" cement. I strongly suspect they have not considered the entire production system unless they use a "solar furnace" for the needed heat.*
PS It is just semantics, but I think "carbon negative" is more correct for process that sequesters carbon.
* I have a US patent, expired long ago, on a solar furnace, which inherently uses a long tube. I solved the classical solar thermal problem. I.e. if absorber is hot enough for good Carnot limited conversion efficiency then the re radiation losses are large. Earlier solutions required wave length selective filters (let the sun light get to absorber but reflect the re-radiation IR back to it). This approach is both expensive and impractical in practice. (Thermal stresses of a passing cloud crack the filter if in the intense flux and a large area filter is much too expensive if in the low concentration sunlight.)
My "absorber" is just the open hole end of the long tube (perfectly black) and sunlight "mirrors" its way far from that end as outer wall of the transparent tube is a metallic film, depositing small amount of thermal energy with each reflection on the walls as it goes deeper into the tube. A "working fluid" flows on the outside of the mirror tube in an annulus, picking up this wall heat and transporting it also farther from the open end absorber, which remains quite cool. - No significant IR loss from it due to the T^4 law.
Thus all the solar energy ends up at the hot end of the tube, far from the entrance. There is intense IR radiation inside the tube at that very hot end, which is quartz at near it softening temperature, but that quarts, "grades into glass" as you approach the open sunlight entrance end. Thus the re-radiation IR is trapped. - It is re-absorbed in the increasingly glass-like sections of the tube wall and can not "mirror back" to the entrance opening and escape the system. I.e. I designed a perfectly black absorber with practically zero re-radiation losses even though temperature achieved is just below softening point of quartz (dull red hot).
My invention is called "Mass flow solar absorber" - you can see detail on line at US patent office site.
POINT BEING: the mass flow could be cement ores and the tube could be rotating with very hot finished cement falling out of the open hot end. One would not just let the hot cement cool, but use that heat, via heat exchanger, to make use of it. (drive steam turbine, etc.)
I never thought of this cement production application, which may be one of the most attractive, until now. The cement ore would be the "working fluid" flowing in the annulus as it would prevent the sunlight from mirroring deep into the tube (is not transparent) as required to keep the hot IR trapped far from the cool "absorber" open hole. It is nice also in that the energy is "stored" in the cement (the de-hydrated ore). Thus solves solar energy's storage problem too!
Does not need to be heated as much, uses magnesium oxide...reaction absorbs carbon during curing.
How abundant is Magnesium Oxide?
Would there be large enough deposits to make a large amount of cement from?
I think it occurs where heat has acted in the past on salts to make the oxide.
Magnesium generally occurs as the sulphate or carbonate.
So you would have to drive off CO2 or SO2 to get the oxide.
Here's some info I found:
As an environmentally friendly building material, magnesium oxide board has several attractive characteristics: fire resistance, moisture resistance, mold and mildew resistance, and strength derived from strong bonding between magnesium and oxygen in magnesium oxide (MgO; pronounced: em, gee, oh). Magnesium oxide boards are used in the place of the traditional gypsum drywall as wall and ceiling cover material or sheathing. It is also being used in a number of other construction applications such as: fascias, soffits, shaft-liner & area separation wall sheathing, and as tile backing (backer board) or substrates for coatings and insulated systems such as Direct-Applied Finish Systems, EIFS, and stucco.
MgO board for building construction is available is various sizes and thickness. It is a non-paper-covered material and generally light gray, white or beige in color. It comes in various grades, such as smooth finishes, rough textures, and utility grades.
Presently MgO board is widely used in Asia as a primary construction material. It was designated as the ‘official’ construction specified material of the 2008 Summer Olympic Games and was used in extensively on the inside and outside of all the walls, fireproofing beams, and as the sub-floor sheathing in the world’s tallest building, Taipei 101, located in Taipei, Taiwan.
MgO is manufactured in a number of areas around the world, primarily near areas where MgO ore (periclase) deposits are mined. Major deposits are found in China, Europe, and Canada. MgO ore deposits in the US are negligible. Estimates put the use of MgO board products at 8 million SQF in Asia alone. It is gaining popularity in the US, particularly near coastal regions.
Sounds like good stuff.
A bit like asbestos without the dangerous fibres.
Thanks for link. Very interesting, but as the Captain notes the MgO deposits may not be as large as the need. If other sources of Mg are used, the carbon negative aspect may no longer be true.
According to the Guardian, the cement uses Magnesium silicate rather than the oxide. The oxide is quite rare.
Vlasopoulos responded that magnesium silicates are abundant worldwide, with 10,000 billion tonnes available, according to some estimates. "In addition, the production process of our cement is of a chemical nature, which means it can also utilise various industrial byproducts containing magnesium in its composition." He is confident the material will be strong enough for use in buildings but acknowledged that getting licenses to use it will take several years of testing.
I'm not sure how good the silicate would be.
It's a pity that the oxide is not more abundant, as the product sounds better than concrete for many purposes.
oops, I thought it said oxide?Please Register or Log in to view the hidden image!
No it did not!
How silicate of me!
I used to slap paint on unsuspecting, innocent canvases, maybe that's why my brain said oxide...
I don't think it's you who is confused.
Some of the reports I have looked at do say Magnesium Oxide.
There seems to be an acceptance of science ignorance in some journalistic quarters.
Newspapers which would kick up hell if a reporter made an elementary mistake, like saying Paris was the Capital of Germany, are quite prepared for those same reporters to make elementary scientific blunders.
The Guardian wasn't one of them.
Hydrated Magnesium silicate is better known to us as Talc.
A very common mineral.
Newspapers and reporters in general aren't known for using scientific names / words properly. I can't even begin to count the number of times I've heard or read about "silicon implants" or "silicone chips."
Accuracy in the media for that sort of thing just isn't what it used to be.
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