1. Uncertainty in EIO-LCA / Hybrid LCA Models

2. Admin Issues Setting Office Hours HW 2 Coming Back
Setting group presentations
1 or 2 classes
can we run late?
How much time?
Or do on Friday?

3. Uncertainty in LCA
Uncertainty exists for all LCA data: mass flows, emissions, impacts, weights and change effects, e.g.
Proprietary data problems
Boundary problems: Lenzen (2000, Journal Industrial Ecology) finds truncation errors on the order of 50% for Australian LCA. Similar to Hocking result.
Measurement, transfer, change, etc.

4. Uncertainty Implications
Consistency and reproducibility of results (e.g. are paper or plastic cups superior).
Certainty of conclusions and usefulness of LCA.
Uncertainty for LCA studies in general obvious - we will focus on EIO-LCA
Data problems, combining data problems, allocation..
Numbers of significant digits – how many digits appropriate for result?

5. EIO-LCA Uncertainty Sources
Survey Errors: sampling and reporting errors – depends on companies and census agencies.
Old Data: IO tables are typically 2 to 7 years old. Last US benchmark: 1997 released 12/2002.
Incomplete Data: reports from only some sectors or plants (e.g. tri sector and threshold limits, holes in census surveys). Note: similarity to boundary problem in conventional LCA!

6. EIO-LCA Uncertainty (cont)
Missing data: Census data missing many topics, such as habitat destruction. Non-monetary inter-sector dependencies also not represented, e.g. congestion effects from truck services.
Aggregation: Sectors too large for detailed analysis on specific products. Problem sectors: ?

7. Uncertainty (cont.)
Imports: EIO treats imports as similar to domestic production.
Model form: Linearity of EIO, lack of substitution as scale economies change.
Mapping and Allocation Problems
Product Prices

8. Uncertainty (Pacca 2003)

9. Mitigating Factors and Approaches
Parameter stability over time
Positive Correlations
More and better data
Simulation analyses
User adjustments

10. Parameter Stability Over Time
Requirements matrix relatively stable over time:
Using 1961 final demand from IO tables of 1939 to 1961 found similar intermediate outputs (Carter, 1970).
Intermediate use relatively constant (Ma, 2003)
Environmental impact vectors more dynamic.

11. Intermediate Use 1972-1997 1972 1987 1992 1997 Manufacturing 49% 41%
Total Intermediate Use Percentages
1972
1987
1992
1997
Manufacturing
49%
41%
39%
35%
Natural Resources
11% 9% 8%
Trade
16%
19%
20%
27%
Services
22%
29%
31%
28%
Miscellaneous 2%
Infrastructure
24%
25%
26%

12. Positive Correlations
Deciding on the best of two designs may be more certain than overall impact due to positive correlations. The designs may share many elements in common, and these elements would be positively correlated. If the element is bad, it is bad for both. If good, it is good for both.
Numerical analysis of effect – Cano (2000).

13. Difference of Correlated Variables
Suppose impact of design a is X and impact of design b is Y. We are interested to know if X > Y or X – Y > 0.
E[X-Y] = E[X] – E[Y]
V[X-Y] = V[X] + V[Y] – 2 cov[X,Y] – correlation means variability is reduced.
Ex: X ~N(1,1), Y ~ N(0,1), Cov (0.5), then E[X-Y] = 1, V[X-Y] = 1, Pr(X-Y>0) = 0.84

14. More and Better Data Mixed picture for more and better data.
No water use data since 1980s in US.
No workfiles for 1997 benchmark released.
Better industrial environmental management systems to collect data.
More international co-operation and public data – international tri.

15. User Adjustments
Many adjustments possible due to known aggregation or emissions problems
Hybrid models including EIO and process models.
Parameter adjustments to reflect non-linearities.
Disaggregating individual EIO sectors.
Bayesian methods applicable here – adjusting estimates based on expectations.
Multiple approaches: EIO-LCA and Conventional LCA.

16. Advantages of Conventional LCA vs. EIO-LCA

17. Disadvantages of Conventional LCA vs. EIO-LCA

18. References
Cano-Ruiz, Alexandro Jose, (2000). “Decision Support Tools for Environmentally Conscious Chemical Process Design,” unpublished PhD Dissertation, MIT.
Lenzen, Manfred, (2000). “Errors in Conventional and Input-Output-based Life-Cycle Inventories,” J. of Industrial Ecology, 4(4), pp
Pacca, S., (2003). “Global Warming Effect Applied to Electricity Generation Technologies,” PhD Thesis, UC Berkeley.

19. Hybrid Life Cycle Assessment
Combining process models and EIO-LCA

20. Models of LCA
“Conventional” LCA, developed by SETAC and EPA, based on process models
Economic input-output analysis-based LCA (EIO-LCA), developed by Carnegie Mellon’s Green Design Initiative and Others
Hybrid models:
Using eiolca model to guide boundary and scope of process models.
Disaggregating or augmenting io model.
Using eiolca for some processes, products and supply chain elements (where sector aggregation is not a major issue), with process models for remainder.

21. Utility of Two LCA Approaches

22. Goals of Hybrid LCA Models
Incorporate the advantages of the two models, reduce disadvantages
Include detailed, process-level data, as well as the economy-wide effects
Provide environmental and economic information about every major product and process in the economy
Quantify the widest range of environmental data
Two obvious high level alternatives for hybrid models

23. Integration of EIO-LCA Data into Conventional LCACn C1
system boundary
commodity
EIO-LCA
Process models

24. Integration of Conventional LCA Data into EIO-LCA
process results
product
commodity Cj
Cj1
Cj2
EIO-LCA

25. Economic and Environmental Implications of Online Retailing and Centralized Stock Keeping in the United States

26. E-Commerce Retail Quarterly Volume ($B)

27. Traditional Retail Logistics System
Factory to warehouse to warehouse to retailer.
Last leg of trip by private vehicle

28. Single Facility Sales LL Bean, Lands End - catalogue sales
Amazon (original), MusicOutpost - web based sales from a single facility

30. How to Model E-Commerce for LCA?

31. Book Publishing Case Study
Traditional System:
logistics: printer > warehouse > warehouse > retailer > home, all by truck/car
unsold returns - roughly 35% for bestsellers
E-commerce System:
logistics: printer > warehouse > distribution center >home, by air and truck.
No unsold returns

32. Comparative Analysis: * is EIOLCA Sector Use
Traditional:
truck transport (1000 mi)*
Warehousing*
production of returns*
reverse travel of returns*
private automobile transport
E-Commerce
air transport (500 mi)*
truck transport (500 mi)*
Warehousing*

33. Comparative Costs ($ 1000s for $ 1 M or 290,000 books)

34. Why are E-Commerce Costs Lower?
Higher transportation costs for e-commerce, but:
Returns of unsold copies
Lower retail transactions costs
Lower (private) automobile cost
Result is cost advantage for e-Commerce

36. Summary Environmental Impacts (per-book basis)

37. Sensitivity Analysis ‘Traditional’ becomes better if:
Local distance to bookstore < 3 miles
Air transport of books > 700 miles
Orders not shipped together
Ecommerce better if:
Switch from Air transport
Multiple origin sites
Greater density of sales.

38. Harry Potter Case 250,000 books shipped on release date by Amazon.com
9,000 trucks and 100 airplanes
2.5 lb. book, 0.7 lb. packaging (3.2 lbs.)
Bookstores got 10 per box
Shopping trips for books avg. 11 miles
Marginal effects

39. This is Research….

40. Some Analysis Issues What are E-commerce future scenarios?
What will happen with local manufacturing technology?
What will be impact of new business models for controlling inventory (warehousing), manufacturing and shipping.
What is appropriate time scale of analysis?

41. Analysis Boundary Issues (cont.)
Buildings - decrease in retail or warehouse space?
Shopping - will individuals substitute other travel for reduced shopping travel?
Computers - what fraction of personal computer burdens should be allocated to E-commerce?

42. Will E-commerce Improve or Degrade the Environment?
Net Effect - hypothesis: depends upon product and processes and upon the analysis boundary.
Appropriate Public Policy -
Don’t ignore service industries in environmental policy.
Consider life cycle costs including social costs.
Take advantage of cost savings to create environmental benefits