Purnell

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Purnell

  1. 1. Operational vs. embedded carbon  p & energy With a cameo appearance from the  Wi h f h functional unit Phil Purnell: Director iRI Phil Purnell: Director iRI Water@Leeds Confluence, 10 March  2010
  2. 2. The iRI The iRI • Institute for Resilient Infrastructure – to provide the knowledge  to ensure that the physical  infrastructure systems  infrastructure systems • The iRI has a unique,  underpinning our way of  world‐class combination  life can adapt to change,  of Engineering Science  both in the way we use  b th i th research with  them and in the social and  Management expertise,  p y physical environment in  which they are designed,  applied through industrial  li d h hi d i l built and operated. collaboration
  3. 3. The Poetry of D.H. Rumsfeld The Poetry of D H Rumsfeld The Unknown Th U k As we know, There are known knowns. There are known knowns There are things we know we know. We also know There are known unknowns. That is to say —Feb. 12, 2002,  We know there are some things We know there are some things Department of Defense  We do not know. news briefing.  But there are also unknown unknowns, http://www.slate.com/ p // / The ones we don't know id/2081042/ We don't know. 
  4. 4. iRI Research & Strategy iRI Research & Strategy • 20+ academic staff • finance, safety and  • structural behaviour of  management in complex  masonry and composite  infrastructure projects i f t t j t structures • numerical optimisation • cement chemistry and  • carbon accounting and  microstructure whole life cycle costing • geotechnical structures  • digital information  • construction materials  standards including recycled and  • flood risk management  waste materials and resilience
  5. 5. A disclaimer A disclaimer http://clovisonline eschool.files.wo ordpress.com/ /2010/01/yoda a.jpg
  6. 6. Operational : Embedded Operational : Embedded • O Operational carbon or energy i l b – heating, lighting, a/c, pumping, decommissioning and  disposal etc; site to grave; ‘running costs’ di l t it t ‘ i t’ • Embedded carbon or energy – materials, manufacture etc; cradle to site ; ‘capital  cost’ • Ratio O:E determines where eco‐£££ should be  spent – E.g. occupied buildings O >> E: spend on insulation etc – infrastructure O ≈ E: need to analyse more carefully
  7. 7. Structural materials: CO Structural materials: CO2 headlines • “1 m3 of wood replacing steel or concrete   saves 1.1 tonne of CO2” [1] [ ] • “Concrete's carbon footprint is fairly large…”  [2] • “Steel construction has no equal in  sustainability. The recycling and reuse rate… in  the UK is 94% [3] the UK is 94% [3]” [1] Wood in Green Building:  Sylvain Labbé, Q‐WEB. Canada Wood Group  (2007). http://www.unece.org/timber/docs/tc‐ sessions/tc‐65/md/presentations/12Labbe.pdf [2] A concrete solution to climate change?: Hayley Birch, Royal Society of Chemistry (2009).  http://www.rsc.org/chemistryworld/News/2009/May/26050901.asp h // / h i ld/N /2009/M /26050901 [3] Sustainable construction ‐ The bigger picture. Steel Construction Institute/Corus.  http://www.corusconstruction.com/en/reference/publications/sustainability_and_environment/
  8. 8. Structural materials: the facts Structural materials: the facts Material eCO2 eE (MJ/kg) ± Timber (Glulam) ( ) 0.7 12 40% Steel: virgin 2.8 37 30% Steel: recycled 0.4 10 30% Concrete (RC50, CEM1) Concrete (RC50, CEM1) 0.2 1.4 30% Concrete (RC50, 50% PFA) 0.1 0.9 30% Hammond, Geoffrey P. and Craig I.  Jones, 2008. 'Embodied energy and  • So who’s right? carbon in construction materials', Proc.  Instn Civil Engrs: Energy, 161 (2): 87‐98.  [DOI:10.1680/ener.2008.161.2.87] [DOI:10 1680/ener 2008 161 2 87]
  9. 9. The functional unit The functional unit • Cannot directly compare  p p p china vs. paper cups – supply, lifespan,  maintenance, disposal… maintenance, disposal… • Compare functional units – e.g. energy/CO2 per 1000  cups of coffee – e.g. coffee consumption per  employee p.a. http://www.faqs.org/photo‐dict/phrase/382/cup.html; http://www.javapackaging.ca/media/ccp0/cat/biodegradable_paper_cup.JPG
  10. 10. Functional unit: example Functional unit: example • Beam to span a 9m gap – Max depth = 700 mm p – 6 kN/m dead load – 8 kN/m live load 8 kN/m live load – Ultimate limit state – 50 year life • RC v Steel v Timber… RC v Steel v Timber… http://www.tgp.co.uk/services/projects/king.html; http://www.mainroads.qld.gov.au/~/media/files/business‐and‐industry/technical‐ publications/queensland‐roads‐technical‐journal/march‐2006/qr_mar06_taromeocreek.pdf
  11. 11. Functional unit: example Functional unit: example • RC • Ti b Timber – b = 0.225 m – UK pine glulam grade  – 40 mm cover 40 C24, ρ ≈ 600 kg m 3 C24 ρ ≈ 600 kg m‐3 – steel ratio 0.029 – b = 0.14 m – assume 90% recycled  assume 90% recycled • NB in real life would NB in real life would  probably need to be  high‐yield steel wider: LTB – 50% PFA replacement 50% PFA replacement – rectangular section rectangular section • Steel • Part 1: How do  – char. yield = 270 MPa char. yield  270 MPa embodied energy and  embodied energy and – UB 385 x 165, 54 kg/m CO2 compare? – assume 60% recycled y
  12. 12. Beam: eCO & eE… Beam: eCO2 & eE 1000 eCO2 / kg eCO2 / kg eE / GJ eE / GJ 14 12 800 10 / kg 600 GJ 8 eE / G eCO2 / 400 6 4 200 2 0 0 RC Steel Timber RC Steel Timber
  13. 13. …cf Materials: eCO2 & eE cf Materials: eCO & eE… 2 eCO2  eCO2 eE / MJ/kg eE / MJ/kg 30 25 1.5 20 J/kg O2  eE / MJ eCO 1 15 10 e 0.5 5 0 0 Conc. Steel Timber Conc. Steel Timber
  14. 14. Other embodied considerations Other embodied considerations • Lifetime of beam if i fb – e.g. if timber beam only lasts  25 years, will need 2  double  the embodied energy/CO2 • Transport to site – RC: 2100 kg, Steel: 500 kg,  g g Timber: 530 kg • On‐site operations O s te ope at o s – in‐situ casting, welding etc. http://www.telegraph.co.uk/news/uknews/6004724/Lorry‐stuck‐on‐bridge‐for‐two‐days‐after‐diversion.html;  http://www.okladot.state.ok.us/newsmedia/i40bridge/gifs/pics‐020717/Welding_on_steel_beams_b.gif
  15. 15. Part 2: Operational energy Part 2: Operational energy • Maintenance i – Steel: painting, Timber: preservative – RC: hopefully none if QC ok, else CP etc. • Disposal – Steel: recycled with high energy cost, or reused – Timber: possible recycled if OK else landfill – RC: partly recycled or landfill – Note: landfill = zero energy/CO2 cost! f gy 2  • importance of ‘weighting’ different impacts: LCA • All fairly small (?) so O:E prob <1 y ( ) p
  16. 16. Case study: domestic housing Case study: domestic housing • H Heavyweight concrete (HC) vs.  i ht t (HC) lightweight timber frame (LTF) • eCO2 (ton) HC 37 LTF 32 (ton): HC = 37, LTF = 32 – carpets ≈ 6 ! • Total CO2: HC 180 LTF 220 Total CO : HC = 180, LTF = 220 • ‘spending’ +5 t during  building saves 40 t over 100y building saves 40 t over 100y 2‐bed, SE England. 65m2  – thermal inertia reduces  100 year lifespan: climate  heating/cooling load  heating/cooling load change factored in change factored in • O:E = 4 – 5  Hacker et al, Embodied and operational  carbon dioxide emissions from housing: A case study on the effects of thermal  d h ff f h l mass and climate change. Energy &  Buildings 40 (‘08) 375‐384
  17. 17. Case study: rooftop wind turbine Case study: rooftop wind turbine • >80% of E  from materials esp.  80% f f i l Al, CFRP • Payback time: time when E + ∫O(t) = 0  – 8%: 4.2y (energy), 3.3y (CO2) – 30%: 1.1y (energy), 0.8y (CO2) – i.e. 20 year O:E –ve, ‐5 > O:E > ‐18 • Intensity (kgCO2/MWh): 27‐41 y( g / ) max 1.5 kW  (13 MWh/year) (13 MWh/ ) – cf inland, coastal wind ≈ 25, 9 eCO2 = 2400 kg coal ≈ 900, PV ≈ 100, nuclear ≈ 5 eE = 23000 MJ 20 year lifespan R K Rankine, J P Chick, and G P Harrison , Energy and carbon audit of a rooftop wind  turbine. Proc. IMechE Vol. 220 Part A: J. Power and Energy pp643‐654.
  18. 18. The Water context The Water context • UK water industry: total 5 Mt CO2 equiv pa – ⅔ waste water, ⅓ potable , p – 0.29 tCO2 / Ml potable water • 1:1 pumping:treatment 1:1 pumping:treatment – 0.74 tCO2 / Ml waste water • 12 1:2 pumping:treatment i – 80% gas & electricity, 20% direct emissions from  sludge and other waste: CH4 ‘GWP’ Environment Agency (2009) report SC070010/R2 “Transforming wastewater treatment to reduce carbon emissions”; Scottish Water  Carbon Footprint Report  2007‐2008. 
  19. 19. The Water context The Water context • Water Framework Directive (WFD) likely to  increase emissions by ≈100 kt CO2 pa y p – Addition of end‐of‐pipe processes to achieve  required water quality can double operational and  required water quality can double operational and embodied CO2 of individual plant – Against background of Carbon Reduction Against background of Carbon Reduction  Committment (‐26% by 2020) • Multiple strategy approach: no silver bullet… li l h il b ll
  20. 20. The Water context The Water context • Source control – avoid substance contact with water in first place • Increased operational efficiency – SUDS: divert runoff to avoid pumping storm water  p p g (‐100 kt CO2) • Switch existing treatment to low‐Energy processes g gy p • Renewable energy generation – CHP from anaerobic sludge digestion (‐100 kt CO2) CHP from anaerobic sludge digestion (‐100 kt CO • Least carbon end‐of‐pipe strategy… Environment Agency (2009) report SC070010/R2 “Transforming wastewater treatment to reduce carbon emissions”; Scottish Water  Carbon Footprint Report  2007‐2008. 
  21. 21. E:O – Treatment processes E:O Treatment processes 20‐year Embodied CO2 k Operational CO2 b d d kg  l O:E treatment type equiv/Ml kg equiv/Ml Trickling filters Trickling filters 10 – 21 224 >10 Reed beds 16 ? (low) <1 Activated carbon 62 66 – 78* ≈1 Reverse osmosis 2‐31 370 – 470 >10 Biological filters 22 224 >10 Activated sludge 10 224 >10 Process level: operationally intensive – focus on O‐CO2,  p y , not E‐CO2 in mitigation strategies Environment Agency (2009) report SC070010/R2 “Transforming wastewater treatment to reduce carbon emissions”. * does not include  regeneration of carbon
  22. 22. Case study: treatment plant Case study: treatment plant • Water treatment works Isle of Water treatment works, Isle of  Man, 37 Ml/day – Floc DAF/Mn contactors Floc‐DAF/Mn • LCA: 40 year life O:E ≈ 7:1 – Embodied: 13 kt CO2 • 80% materials, 20% M&E – Operational: 85 kt CO2 • 70% electricity & sludge, 30%  embodied in chemicals b d d h l Calculating the carbon footprint of a water treatment  • Treated water pumping: plant. Paul Hunt et al. Northern Water Conference and  >30 kt >30 kt CO2 Exhibition November 2008, Manchester.  , http://www.envirolinknorthwest.co.uk/Envirolink/Events0 .nsf/0/8025739B003AADE3802574AA002778CF?OpenDo cument
  23. 23. Conclusions • Simple comparisons based on materials’  y y y ‘renewability’ or ‘recyclability’ are not valid – define a functional unit • Cannot generalise about O:E ratio Cannot generalise about O:E ratio – ‘Spend’ E to reduce O • Embodied carbon ≈ 2:1 waste:potable water • Most treatment processes & plant O >> E Most treatment processes & plant O >> E – Operational focus give greater CO2 benefit

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