Towards the Best Practice Environmental Sustainability Metrics for Chemical Engineers: Using a Hierarchical Life Cycle Impact Assessment

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Towards the Best Practice Environmental
Sustainability Metrics for Chemical Engineers
Using a Hierarchical Life Cycle Impact Assessment
AICHE 2003 Annual Meeting Nov. 16-23, San
Francisco

• Xun Jin and Karen A. High
• School of Chemical Engineering
• Oklahoma State University

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SusCAD
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Sustainability Concept

• Definitions
• - Inter/intra-generation equity view
• - Critical limits view
• - Competing objective view

• Basic characteristics
• - Vagueness
• - Complexity
• - Transdiscipinarity
• - Flexibility

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Difficulties for Chemical Engineers

• Conceptual intricacy
• Perspective diversity
• Knowledge deficiency
• Relevancy emphasis

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Metric Transformations

• Paradigm shift Greening to Sustaining
• - NAE NRC (1999)

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Best Practice Metrics

• Is there a set of best practice metrics in
  general ?

- Impossible no-size-fits-all - Trade-offs
between desired features, cost and feasibility -
Lack of systematization

• What will help?
• - Identified endpoint(s) and the pertinence to
  the endpoint(s)
• - A well-defined assessment framework that
  allows operational diversity
• - A scientifically sound classification

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Endpoint and Causality

• Causality represents the relevancy to
  sustainability
• Traditional isolated endpoints ignored the
  integration of the environment
• Extended endpoint

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Endpoint Human Welfare ?

• Bad
• - Still Fuzzy
• - Less defendable environmental relevancy
• Good
• - Independent to the subsystems
• - Endpoint reflects maximum relevance, provide
  an important criterion to evaluate alternatives
• - A universal endpoint, Canary in coal mine or
  common currency

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Assessment Framework

• LCA is the best candidate
• - Well-developed theoretical framework
• - Prosperous resources and applications

LCA derived methods Developer Year
EDIP Wenzel 1997
CML Heijungs 1992
CML Guinee 2002
Eco-indicator Pre 1995
Eco-indicator Pre 1999
TRACI USEPA 2002

• Provides no default metric
• Variety in metric selection

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Handling Variety

• A multi-level hierarchy could potentially tackle
  the inconsistency and classify the metrics
• Existing frameworks include

Pressure-State-Response (PSR) OECD
Driving force-State-Response (DSR) UNCSD
Pressure-State-Impact-Response (PSIR) UNEP
Driving force-Pressure-State-Impact-Response (DPSIR) EU
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A SSEIW Hierarchy

• Stressor
• The discharges associating with a given human
  activity
• Status
• The induced state change of the exact
  environmental compartment that the stressors are
  directly exerted on
• Effect
• The resulting environmental impacts that embody
  certain aspect of societal concern
• Integrality
• Component completeness, structural rationality
  and functionality of the environment as a whole
• Well-being
• The damages caused by all the prior aspects to
  human welfare

Impact
CFCs emission
Stressor
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LCA Framework
I Define impact category II
Identify category indicator III Select
characterization model VI Classification
V Characterization VI
Normalization VII Grouping VIII
Weighting
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Operational Issues

• Bottom-up vs. Top-down
• - Bottom-up
• The target problem is analyzed first without a
  concrete goal. This approach may not be adequate
  for the achievement of specific goals, mostly
  adopted by scientists, engineers and other people
  who is interested in the performance of the
  particular system
• - Top-down
• The top-down scheme starts with defining the
  assessment goals and aims to evaluate the
  accomplishment of specific goals. The limitation
  of this approach is that pre-defined goals
  sometime have to be compromised with indicator
  availability. Mostly applied by managers,
  environmentalists, policy-makers

Top-down
Bottom-up
CFCs emission
Stressor
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Operational Issues (cont.)

• Two-dimensional Impact Categorization

Across the causal chains
Status
Effect
Along the causal chains
Integrality
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Operational Issues (cont.)

• Indicator and characterization model selection
• - Compatibility of the indicators across
  multiple levels depends on how to utilize them in
  decision-making
• - Develop a characterization model

Status Selected property environmental model
Effect Selected property environmental model fate, exposure and effect analysis
Integrality Eco-modeling systems analysis
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Example

• Ground level ozone formation

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Example (cont.)

• Different metrics of measuring environmental
  sustainability

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Conclusion

• Keep an open mind
• Best practice is
• - Goal satisfaction at allowable cost with
  available resources
• - Apply Life Cycle Assessment theoretical
  framework
• - Maximize sustainability relevancy in a valid
  manner
• - Customize metrics according to the proposed
  hierarchy
• - Effective decision-making paradigm
• The future research
• - Case study
• - Human welfare indicator
• - decision-making using pareto optimality
  concept

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Acknowledgement

• Environmental Institute _at_ OSU

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Questions