[Committee] How much land for Biomass (WAS : Effect of methane leakage on Carbon footprint of gas)

Sun Feb 25 21:20:42 UTC 2007

 I agree with your rough figure

 a managed forest absorbs 0.18\,kg\,\COO\ per m$^2$ per year.
 So to balance emissions of one tonne of \COO\ per year,
 one needs 5500\,m$^2$ of managed forest.
 To balance 1\,Gt\,\COO\ per year (the Branson advertisement's figure),
 one needs 5.5\,million km$^2$ of managed forest.

 For comparison,
 agriculture currently uses 40\% of global land area.
 Global land area is {{148}} million km$^2$.
 So sequestration by managed forest would require 
an area equal to 3.7\% of the world's land, and equal to
9\% of the area currently used for agriculture.
 And somewhere safe to put 1400\,million\,m$^3$ of dry wood every year.

Where would you shove the 
dry wood that is safe? Up Richard Branson?

David

* Robin Smith <robincsco at hotmail.com> [2007-02-25 20:24]:
> This is probably a bit off topic but please can you give me your quick
> opinions. I'm doing the maths on the CCS yields possible from Biomass with
> all the lifecycle process deficiencies included. Target is 1Gt CO2 per year
> as per the Virgin Earth Prize!
> 
> Question) Given the land available, efficiencies and energy output, would 9%
> of the global land surface area needed to yield the 1Gt be a field too far
> in your opinions?
> 
> Brgds
> Robin.
> 
> > -----Original Message-----
> > From: Steve Stretton [mailto:sjstretton at googlemail.com] 
> > Sent: 27 January 2007 01:48
> > To: 'David J.C. MacKay'; 'Gunnar M?ller'
> > Cc: committee at zerocarbonnow.org; 'Adrian Wrigley'; 'Adam 
> > Barnes'; 'Jonathan Kohler'; 'Philip Sargent'; 'Philip 
> > Slater'; 'Robin Smith'; 'Ronan Kavanagh'
> > Subject: FYI: Effect of methane leakage on Carbon footprint of gas
> > 
> > As far as gas leakages are concerned...
> > 
> > The effect of CH4 (Global Warming Potential over 100years by 
> > mass = 23) [1] translates to 23x(16/44)= 8.4 times the GHG 
> > effect of CO2 per Molecule.
> > 
> > So we multiply the leakage rate by 8.4 to get the additional 
> > greenhouse effect If we assume (cf. [2]) a high (4%) methane 
> > leakage rate, then methane leakage has 34% the 100y-effect of 
> > the CO2 from burning the same gas.
> > 
> > Assuming 350g/kWh for gas electricity, there is a boost of 
> > ~120gCO2 equiv/kWh so ~470gCO2equiv/kWh total GHG effect. 
> > (this is consistent with the *text* which says "around half 
> > that of coal (~500gCO2eq/kWh)"; figure 3 is lower).
> > 
> > Assuming 50g/kwh for CCS (85% effective[3]), we would then 
> > also add 120g/kWh from methane leakage to get 170g/kWh for gas + CCS. 
> > So it's a significant increase, but still slightly below the 
> > 240g/kWh shown on figure 3.
> > 
> > I haven't included the extra gas needed per kWh for CCS in 
> > order to power the compression and storage of the CO2, but 
> > I'm assuming this isn't too significant.
> > 
> > So gas leakages are significant in the case of gas+CCS, but 
> > don't seem to explain all the increase.
> > 
> > All the best,
> > Steve
> > 
> > (Apologies for anyone copied in but not interested).
> > 
> > 
> > NOTES
> > 
> > I enclose the figures from the POST note. BTW there's lots of 
> > these post notes on all sorts of interesting topics (there's 
> > one on CCS) and they're quite useful.
> > http://www.parliament.uk/parliamentary_offices/post/pubs2005.cfm
> > 
> > 
> > [1] IPCC 2001 quoted in Wikipedia
> > http://en.wikipedia.org/wiki/Global_warming_potential
> > The effect of Methane per unit mass is 23
> > (23 times more potent than CO2 over 100 years).
> > 
> > [2] James Lovelock 'The Revenge of Gaia' p74-76. Original Sources:
> > Lelieveld J. et al., Nature, April 2006
> > (Max Plank Institute for Chemistry, Mainz, Germany). Leakage 
> > rate of 1.4% from Russian Pipelines, comparable with 1.5% 
> > leakage rate reported in the US. Does not include leakage at 
> > production and burning sites.
> > cf. Society of Chemical Industry (2004). Overall leakage rate 2-4%
> > 
> > [3]Ecofyn study on CCS, included
> > -----Original Message-----
> > From: David J.C. MacKay [mailto:mackay at mrao.cam.ac.uk]
> > Sent: 26 January 2007 14:33
> > To: Stephen Stretton
> > Cc: Gunnar M?ller; committee at zerocarbonnow.org; Adrian 
> > Wrigley; Adam Barnes; Jonathan Kohler; Philip Sargent; Philip 
> > Slater; Robin Smith; Ronan Kavanagh
> > Subject: Re: Parliamentary Office of Science and Technology / 
> > Electricity Generation Carbon Footprints
> > 
> > 
> > very nice document.
> > 
> > The only thing I didn't understand is figure 3 gas with CCS.
> > 
> > Why do they have such an ineffective figure for CCS?
> > Anyone understand?
> > 
> > Is it because of accidental leakage of CH4? (Stephen's suggestion.)
> > 
> > thanks
> > 
> > David 
> > 
> > * Stephen Stretton <sjstretton at googlemail.com> [2007-01-26 13:56]:
> > > Hi,
> > > I've just noticed the work of the Parliamentary Office of 
> > Science and 
> > > Technology (POST). "POST is an office of both Houses of Parliament, 
> > > charged with providing independent and balanced analysis of public 
> > > policy issues that have a basis in science and technology."
> > > http://www.parliament.uk/parliamentary_offices/post/new.cfm
> > > You can register for email updates online.
> > > 
> > > Attached is the report of the carbon footprint for electricity 
> > > generation. Any comments?
> > > 
> > > Best regards,
> > > Steve
> > > 
> > > 
> > > 
> > > POST is grateful to all contributors and reviewers. For further 
> > > information on this subject please contact Dr Stephanie 
> > Baldwin at PO 
> > > ST. P arliamentary Copyright 2006
> > > 
> > > Parliamentary Office of Science and Technology, 7 Millbank, London 
> > > SW1P 3JA
> > > 
> > > t el: 020 7219 2840 email: post at parliament.uk
> > > *
> > > 
> > > www.parliament.uk/post
> > > *
> > 
> > 
> > 
> > -- 
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> > David J.C. MacKay                                 
> > mackay at mrao.cam.ac.uk
> >                              
> > http://www.inference.phy.cam.ac.uk/mackay/
> >       Cavendish Laboratory, 19 J J Thomson Ave, Cambridge CB3 
> > 0HE. U.K.
> >     (01223) 339852 | fax: 354599 | home: 740511 
> > international: +44 1223
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-- 
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David J.C. MacKay                                 mackay at mrao.cam.ac.uk
                             http://www.inference.phy.cam.ac.uk/mackay/
      Cavendish Laboratory, 19 J J Thomson Ave, Cambridge CB3 0HE. U.K.
    (01223) 339852 | fax: 354599 | home: 740511 international: +44 1223