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Sunday, 24 May 2009

Concrete Thinkers_Putting CO2 emissions into perspective_but how sucessful are they in this?

In my previous post, I recommended, from my scant readings of non-metallic materials, The Portland Cement Association ,Concrete Thinkers _ page and mentioned in my post, what I saw as short comings in several science news releases from the scientific community.

Specifically, I felt that the scientific teams mentioned lacked commitment and resolve in setting their sights and hence their objectives to the highest levels, ie. choosing near zero-carbon emissions and not categorically "zero-carbon emissions". [Either the scientists in question appeared to lack commitment and resolve in setting their objectives or having seen how difficult getting results from the lab. to full scale in industrial ( socio-economic) practice preferred to remain modest and prudent, I did not know. But we shall see in posts to follow that more ambitious approaches seek not only to achieve zero-emissions but carbon negative standards ie. CO2 absorption rather than emissions.]

Back to Concrete Thinkers site,while it does give a good summary of the state of the art, progress and approaches which now lead to 2% or less CO2 emissions with referenced white papers, the paragraph which caught my eye for future reference was as in the title of my current post title "Putting CO2 emissions into perspective". Upon a second reading with intent to blog I found the paragraph guilty of many of the faults over and above the use of non- International standard Organisation (ISO) units. The paragraph leads the reader to believe that one will gain a much more balance view of activities leading to specific and CO2 emissions based on units and comparable chores (daily,annual etc.) Meaningless comparisons, activities are not comparable between one another, no comparable standard activity is taken when common energy units are an obvious choice and these could be related to some common daily "global" activity cf. Prof David J.C. MacKay's approach referenced below:

Read Concret Thinkers page with some specific critical comments as follows:

"The manufacture of cement produces about 0.9 pounds of CO2 for every pound of cement. Since cement is only a fraction of the constituents in concrete, manufacturing a cubic yard of concrete (about 3900 lbs) is responsible for emitting about 400 lbs of CO2.[1] The release of 400 lbs of CO2 is about equivalent to[2]" [refs.1,2 refer to papers on their site]:

* The CO2 associated with using 16 gallons of gas in a vehicle (what sort of vehicle!!!)
(16x3.79 litres = 60.64 litres and if your Limousine gives you 100 kms per 5 litres then, => 60.64 /5)x100 = 1212.8kms and say at a speed of 100km/h Then you get 12.12h driving pleasure!)

* The CO2 associated with using a home computer for a year (24h a day connected?)
* The CO2 associated with using a microwave oven in a home for a year (a few minutes or 1 h, lets say per day?)
* The CO2 saved each year by replacing 9 light bulbs (N° of W (Watts and KWh?) in an average house with compact fluorescent light bulbs (Units please?)

Other sources responsible for CO2 emissions include: [I have given the conversion factors below to play with but....

* 28,400 lbs for an average U.S. house in a year
* 26,500 lbs for two family vehicles in the U.S. in a year
* 880,000 lbs for a 747 passenger jet traveling from New York to London

The reason concrete is responsible for 1.5 to 2% of the U.S. anthropogenic CO2 (that is, due to humans) is due to the vast quantities of concrete used in the world around us.

Metrics - Conversion
lbs, US: 1 pounds (lbs) (avoirdupois) is equal to 0.45 kilograms

Yards cu: 1 cubic yards is equal to 0.76 cubic meters
1 cu yd concrete 3900lbs ( kg) => 400lbs CO2 )

gallons US: 1 gallon (US) is equal to 3.79 liters
gallons GB: 1 gallon (British) is equal to 4.55 liters

miles 1 miles (statute) is equal to 1.61 kilometers.

Concrete
400lbs/3900lbs roughly, 1/10 =10% CO2
Therefore, For every unit weight of concrete produced the weight of CO2 emissions is 1/10 or 10% of the weight of concrete produced
Cement
For every unit weight of cement produced approximately the same weight of CO2 is emitted. (or 1 unit of cement produced roughly 0.9 or 90% of CO2 emissions is also produced)

Does anyone know of a better account?

Sources and References:

1. The Portland Cement Association ,Concrete Thinkers _ page

2. A much better approach is that of Cambridge,UK, Prof. David J.C. MacKay, in his freely available ebook Without Hot Air!

What a coincidence (serendipity) I came across David MacKay's Video on light bulbs!

3. CO2 and other greenhouse gases GHG's
Global Warming Potentials (GWP) and Atmospheric Lifetimes (Years)
LINK to US Environment Protection Agency (EPA).

NB. To be fair here are a couple of graphs from references on the Thinkers Site that are more informative than the written paragraph presented by the Thinkers. All and more are referenced on the Thinker site cf. in particular the Stewardship pages


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High Purity Cr sources for Superalloys

Energy for th Future:Phil.Trans.A-Vol. 365, N° 1853 / April 15, 2007, curtesy The Royal Soc. London

Engineered foams and porous materials: Phil Trans A. Vol 364, N° 1838 / 06 curtesy_The R Soc. Lond