TED Conversations

James McSparron

Student, University of Ulster

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Can 1 cubic meter of wood really hold 1 tonne of carbon? I would not have thought so.

“Why we should build wooden skyscrapers” http://tres.me/1pZYk3N
Michael Green states in his TED talk that a cubic metre of wood can hold 1 tonne of carbon.
Is a tonne of carbon not the same as a tonne of coal or the same as a tonne of feathers?
It could be said that Michael made a small mistake but someone took time to create a diagram to support the statement.

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    Apr 9 2014: James,
    I addressed your question the best I could about carbon and wood etc. But in further thinking about this, I would be remiss if I didn't address Green's comments about 30 story buildings. He is proposing the use of large laminated wooden beams to provide structural support in the building of these skyscrapers. I have seen the use of laminated beams in large church sacristies. Beautiful. But, the reason for steel and concrete use in high rise building is practicality, efficiency and of course... money.
    High rise are built on cost per useable square footage within the building. So, structure is kept to the minimum. The cross section of iron is much smaller then the cross section of an laminated beam. Then there is the cost of building a laminated beam, it is a laborious process. So, is there a use for structural wooden beams? Absolutely. Will the widespread use of wooden high rise buildings come, unlikely. Although I can see some built for the unique image... sort of an architectural art piece.
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    Apr 8 2014: James,
    Not often do your countrymen come up on TED. I am totally envious of you country, my visits too short and
    a more generous people have ever I met. Of course, I might have given them the impression I had Irish ancestors... they were Mediterranean Irish, but close enough. To your question...

    There have been some massive wooden structures created over time, some temples in Japan come to mind.
    However, the premise of using wood to create "skyscrapers" to address the carbon issues... a difficult .
    From a pragmatic point of view, getting pass building codes, costs, construction difficulties, etc., etc.
    I couldn't find any of the common used woods that came up to the one ton / m rates in the USA. So, I expended my search to world wide wood products and did find woods that met the numbers....the problem was that these woods came from endangered forest or on an do not import lists, costs were prohibitive for what could be obtained. etc. etc.
    I have got to think there is a better way to address carbon issues.
    For the record, I used cellulous to determine atomic weight for carbon and then density properties of the various woods to calculate an amount of carbon per ton. Not laboratory accurate but enough to see the problems. My conclusion after reading Mr. Green's talk is that it is one of wistful thinking.
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      Apr 8 2014: http://tres.me/1pZYk3N
      Hi Mike,
      This is a link to the Michael Green talk I was referring to in my unthinking haste. Have a look if you haven't already.
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        Apr 8 2014: I did read over his talk thank you.
        Now appreciate that there is a schism between engineers and architects.. Architects are artist and engineers are like scientist and sometimes there are divergent views. I got stories. However as I said, the practically of massive vertical structures in wood even if could be built would not as I conclude be an effective way to address carbon problems...
        What is the atmospheric carbon dioxide there, it has to be higher there in lush greenery of Ireland then these deserts of Texas.
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          Apr 8 2014: 388.95 conc (ppm) in West Ireland. Source: Met Eireann 2008.
          Yeah, lush and wet. Too wet.
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    Apr 8 2014: You have misunderstood Michael Green's statement and graphic. He said "One cubic meter of wood will store one tonne of carbon dioxide." And that's what his graphic illustrated with an elephant standing on a block of wood: 1 tonne CO2 and 1M^3 of wood.

    Carbon dioxide is not the same as carbon. What he means is that one tonne of carbon dioxide goes into growing one cubic meter of wood. He did not say that there is one tonne of carbon in a cubic meter of wood.

    A cubic meter of wood will weigh different amounts (or it will have different amounts of mass) depending on the type of wood. Therefore it will also have different amounts of stored carbon, and will probably have used different amounts of carbon dioxide as it grew, so Michael probably used some average for different types of wood commonly used in construction.
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      Apr 8 2014: Thanks for that Carl. I understand now. Dauh!
      I was worried that TED had let an error slip through to a talk and excited that I'd become smarter than Michael Green.
      May the force be with you.