I believe that the difference is that the CO2 that we exhale was taken
out of the atmosphere recently, and does not affect the carbon
balance, while the CO2 from fossil fuels has been in the ground for
millions of years and does affect the atmospheric balance of carbon
when released.
Also, just as the straw bales and other materials may have been
trucked in from out of state, the portland cement you are using was
probably trucked in from fairly far away as well.
There are some other factors stacked against portland cement - there
are currently large debates here in CO over concrete plants that are
burning tires in their kilns and releasing dioxins and other nasty
stuff that neighboring communities are not happy about.
In some areas of the world the limestone used for making cement is
stripmined, displacing native people and destroying large amounts of
wildlife habitat. The same could be said for a lot of the coal that
is used as well, as well as drying up aquifers to transport the coal
in slurry form.
With adobe and rammed earth, you would also have to ask what is the
footprint of running fossil fuel machinery to excavate, sift and mix
the dirt and hydraulically compress the earth. Unless, of course,
they are running the machinery on biodiesel.
Apparently there are emerging alternatives:
Carbon neutral concrete:
and
• ecocement – magnesium based replacement for ordinary (portland)
cement which soaks up (sequesters) carbon dioxide as it cures. A sharp
contrast to portland cement. Experts predict it will take 10 years for
this to be a feature in the market place. We aim to help this
innovation get over the market inertia and shrink this time frame.
--- In papercreters@yahoogroups.com, "clydetcurry" <clyde@...> wrote:
>
> in other words- if we sit around debating for a year over the fact we
> will exhale more CO2 than building our house would have produced-
> amazing- boy am I glad you folks have gotten around to this - Clyde T.
> Curry--- In papercreters@yahoogroups.com, Greg House <ghunicycle@>
> wrote:
> >
> > My father worked in the cement and lime production industries most
> of his life. From what I've seen from his work, most cement kilns are
> fired with coal.
> >
> > Greg
> >
> > ----- Original Message ----
> > From: Mikey Sklar <sklarm-yahoo@>
> > To: "papercreters@yahoogroups.com" <papercreters@yahoogroups.com>
> > Sent: Wednesday, August 8, 2007 10:32:47 AM
> > Subject: Re: [papercreters] Re: 26lbs of CO2 per bag of Portland
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > When Portland cement is being made from limestone,
> natural gas or
> >
> > propane is used to heat the limestone. White portland would have a
> >
> > even higher CO2 footprint as it is cooked longer.
> >
> >
> >
> > On Aug 8, 2007, at 9:21 AM, "slurryguy" <slurryguy@yahoo. com> wrote:
> >
> >
> >
> > > Does clinker outgas CO2 as it is getting fired? How much?
> >
> > >
> >
> > > I'm not disagreeing with your overall point. I actually agree.
> >
> > >
> >
> > > --- In papercreters@ yahoogroups. com, Mikey Sklar
<sklarm-yahoo@ ...>
> >
> > > wrote:
> >
> > >>
> >
> > >>
> >
> > >> I have been tormented by a few local adobe and straw bale builders
> >
> > >> for my use of Portland cement. They point out to me that by using
> >
> > >> a high energy product that I am destructive to the environment. I
> >
> > >> had my doubts and decided to run some numbers this evening about
> >
> > >> just how much CO2 was being produced to create a bag of portland.
> >
> > >> The answer I came to was less than 26lbs of CO2 per 94lb bag of
> >
> > >> portland. I suppose I can now point out to the so called green
> >
> > >> builders who are hauling straw bales or pre made adobes from across
> >
> > >> state boarders that their CO2 footprint is orders of magnitude
> >
> > > larger
> >
> > >> than my own.
> >
> > >>
> >
> > >> - portland cement 4,700,000 million btu per ton
> >
> > >>
> >
> > >> - convert btu's per ton to one bag of Portland (94lbs)
> >
> > >> * 1 ton 2000lbs
> >
> > >> * 2000 / 94 = 21.28
> >
> > >> * 4700000 / 21.28
> >
> > >> * 22,0864.66 btu's per bag
> >
> > >>
> >
> > >> - convert btu's of natural gas to pounds of CO2
> >
> > >> * 1 million BTUs (NG) will produce 117.08 pounds of CO2
> >
> > >>
> >
> > >> - convert btu's per ton of portland to pounds of CO2
> >
> > >> * 4,700,000 / 1,000,000 = 4.7
> >
> > >> * 4.7 * 117.08
> >
> > >> * 550.276 lbs of CO2 per ton of Portland made from Natural Gas
> >
> > >>
> >
> > >> - convert lbs of CO2 per ton of Portland to bag of Portland
> >
> > >> * 550.276 / 21.28
> >
> > >> * 25.86 lbs of CO2 per bag of Portland
> >
> > >>
> >
> > >> When we consider that jet fuel, diesel, and car fuel all produce
> >
> > >> about 20 lbs of CO2 per gallon we can see that a bag of Portland
> >
> > >> is producing the same amount of CO2 as driving 20 miles in your
> >
> > >> truck.
> >
> > >>
> >
> > >> If you want to bring yourself to neutral on CO2 for your Portland
> >
> > >> usage. Consider that the average tree will absorb 26lbs of CO2 per
> >
> > >> year.
> >
> > >>
> >
> > >> Keep in mind that we humans on average exhale over 2lbs of CO2 per
> >
> > >> day.
> >
> > >>
> >
> > >
> >
> > >
> >
> > >
> >
> > >
> >
> > >
> >
> > > Yahoo! Groups Links
> >
> > >
> >
> > >
> >
> > >
> >
> > >
> >
> >
> >
> >
> >
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> >
> >
> >
> >
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