Advanced Environmental Assessments

Transcription

1 Lecture: Subjectivity in LCA - a matter of perspective 3 December

2 What we will learn today Know the main subjective choices in LCA Know how to deal with them Identify them in an LCA case study 2

3 Content Introduction Subjectivity in Goal and Scope definition Subjectivity in Inventory Analysis Subjectivity in Impact assessment How to deal with subjectivity Discussion: LCA of christmas trees 3

4 Main characteristics of LCA decision support tool life cycle based, i.e. not limited in time and space broad scope of environmental impacts not verifiable by means of experiments not (yet) mandatory internationally standardised (ISO) 4

5 Where are subjective decisions located? Goal and scope definition Inventory analysis Interpretation Impact assessment 5

6 Which assessment tool Life cycle approach: yes or no Kyoto-protocol and CO 2 reduction targets based on national GHG inventories In discussion: Transferred benefits and avoided costs due to international trade Transferred benefits: export of CO 2 -free goods to countries that can avoid CO 2 -intensive production Avoided costs: import of CO 2 -intensive goods to avoid domestic CO 2 -emissions 6

7 Mio. t CO2-eq. Subjectivity in LCA Transferred benefits: Avoid GHG-emissions abroad Which assessment tool Swiss greenhouse gas emissions Total HFC PFC SF6 CH4 N2O CO2 Stromexporte electricity exports 0-20 BAFU (2007) Domestic Direkt CH Net trade of goods Saldo für Waren Saldo für Dienstleistungen Net trade of services Total Benefits - Transferred Stromexporte benefits Total HFC E E-05 PFC E E-04 7

8 Decisions related to goal and scope Definition of functional unit - selection of reference flow - selection of alternatives Selection of environmental impacts System boundaries Inclusion or exclusion of - capital goods - other parts of the life cycle 8

9 Example: Red Bull Air Race (Interlaken 2007) Compensation of climate change impact by myclimate 9

10 Cradle to cradle: compostable seat cushions in Airbus A380 (2010) I can feel very nice on Michael's* seat covers in the airplane. Nevertheless I am still waiting for a detailed proposal for a design of the other % of the Airbus 380 after his principles. Friedrich Schmidt-Bleek *: Michael Braungart 10

11 Functional unit: Maslow s hierarchy of needs Usefulness of product analysed in an LCA is not part of goal and scope definition 11

12 Alig et al. (2012), ART: Environmental Assessment of Beef, Pork and Poultry 12

13 Comparative LCA of beef meat BF: Bull fattening PEP: proof of ecological 13 performance SC: Suckler cow

14 Environmental impacts of food items (per kg) 14

15 Definition of functional unit and reference flow Definition of functional unit and reference flow can be highly decisive Too narrow definition may be misleading LCAs on weight reducing parts in private cars: saved weight is used up by additional equipment LCA of time saving measures in traffic infrastructure: Commuting time is constant: Travel distance tends to get longer ) => rebound effects 15

16 Rebound effect: consumption as usual Girod et al

17 Rebound effect of switching from car to bicycle Environmental impact per km differs time needed and costs per km differ Rebound effect: time available is constant income available is constant May be spent on car driving, mobility or anything else more of the same (car driving): E RE = E Car km E Bike km t Car t Bike E Car km more of similar (mobility): E RE = E Car km + t Bike t Car E Mobility time E Car km E Bike km 17

18 Greenhouse gas emissions for assessing rebound effects Girod et al

19 Rebound effects in travelling Comparison of A (Car) and B (Bicycle): Reduction of impact - w/o RE: 98 % (194 4)/194 - RE time (more of the same): 99 % (194*3.5/1.5 4)/453 - RE time (more of similar): 185 % ( ( )/60*5000)/194 - RE income (more of the same): 77 % (194*0.02/0.21-4)/18.5 Girod et al

20 Functional unit definition Commissioner: EUROFER Consultant: Boston Consulting Group 20

21 Reduction potentials attributable to steel? 21

22 Selection of alternatives Decisive in comparative studies include - zero alternative - completely different technologies - exotic products Ensure comparability 22

23 Example: Electric mobility electric diesel/gasoline 23

24 Selection of environmental impacts Which environment to protect? Many so-called LCA s focus on cumulative energy demand or carbon footprint (or even just CO 2 ) Toxicity-related impact categories often excluded because of uncertain modelling Land use related impacts often excluded because of no accepted method available yet 25

25 EPD Nuclear Power Station Beznau, CH Climate change impact in g CO 2 -eq/kwh 26

26 EPD Nuclear Power Station Beznau, CH Impacts from nuclear fuel fabrication Majak, RU 27

27 Environmental assessment of mobility

28 Content of Apeldoorn Convention (2004) On how to assess toxicity of metals report on deficiencies of current assessment models no business nor policy decisions without further discussion take into account metal speciation, in particular amount of dissolved metal if dominant influence of toxicity on results and conclusions, carry out sensitivity analysis with time horizon 100a Impact factors of metals emitted to oceans should be set to 0. It may be different for coastal seas. 29

29 Interpretations of Apeldoorn Convention exclude toxicity impacts in general exclude metals from toxicity assessments exclude long-term metal emissions from toxicity assessment apply toxicity impact factors as usual but carry out sensitivity analysis if impacts are relevant apply toxicity impact factors as usual but highlight deficiencies in the report and summary 30

30 Consequences on e.g. biofuels assessment relevant environmental impacts of agriculture are not captured - impacts due to fertilizer and pesticides - land use by intensive agriculture comparisons of biofuels with conventional fossil fuels are biased 31

31 Inventory Analysis Subjectivity in Inventory Analysis Choice of modelling approach: - attributional model - consequential model see lecture 1. Oct. 15 Choice of allocation principle in joint production and recycling: - cut-off approach - avoided burdens approach see lecture 24. Sept

32 Impact Assessment Subjectivity in Impact Assessment Preference in safeguard subjects (ecosystem, human health, man made assets, resources) Time preference (e.g. après nous le déluge ) Preference of place (e.g. not in my backyard ) Risk perception Perception of uncertainty 33

33 Impact Assessment Time in LCA Long time periods between today and - some activities - releases of pollutants - impacts on environment years 34

34 Impact Assessment Time preference Outcome of discussion at LCA Forum 22: Long-term impacts should be considered Impacts occurring in near future (less than 100 years) should be separated from far future impacts Some prefer to weight short term impacts differently Uncertainty in data is much higher with regard to long-term effects No consensus on how to integrate far future emissions in impact assessment 35

35 Impact Assessment Time preference / 2 Application in External cost assessments: Level of interest rate is decisive for relevance of future effects Even low interest rates (2 to 3 %) lead to little importance of effects occuring more than 100 years from now Usually several discount rates are applied, at least in sensitivity analyses, including a 0% rate. 36

36 environmental impacts Impact Assessment Discounting: effect of different pure time preferences discount rate time [years] 37

37 Impact Assessment Preference of place In LCA usually not distinguished Sometimes information on the shares of domestic versus abroad emissions / impacts requested External cost assessments: value of life year lost differs according to national price levels Concept of equity weighting (EW, or purchasing power parity, PPP) eliminates these differences Results with and without PPP. 38

38 Impact Assessment Example: CO 2 damage costs 1 ton CO 2 : 6 EUR 300 EUR??? far future far away 39

39 Impact Assessment Challenges with climate change damage costs Size of damages is uncertain Damages caused by climate change occur delayed, not (necessarily) where emitted Applying the concepts of discounting equity weighting (purchase power parity)

40 Impact Assessment Source: Anthoff 2007, NEEDS project Example: marginal damage costs of CO 2 US-$ per ton of Carbon 41

41 Synthesis Ways to deal with subjectivity Cultural Theory and Perspectives: ReCiPe 2008 (see Bachelor script, p.82ff.) Apply clearly defined concepts: Strong / weak sustainability as a basis for allocation in material recycling (see lecture Allocation, ) Apply position-oriented allocation in joint production (see Bachelor script, 2.3.6, p.47ff.) Sensitivity analyses 42