Life Cycle Assessment: History and Framework H. Scott Matthews Civil and Environmental Engineering Carnegie Mellon University

Course Comments Brief (re)-Intros Projects Intended to help you start practicing Will summarize, not repeat, what is found in readings Make sure you know ‘definitions’ from ISO documents

Life-Cycle Assessment (LCA) A concept and methodology to evaluate the environmental effects of a product or activity holistically, by analyzing the whole life cycle of a particular product, process, or activity (U.S. EPA, 1993). LCA studies analyze the environmental aspects and potential impacts throughout a product's life cycle (e.g., cradle-to-grave) from raw material acquisition through production, use and disposal (ISO).

LCA Uses Process analysis Material selection Product evaluation Product comparison Policy-making Measuring performance Marketing

Components of LCA - 3 or 4 I’s Inventory Impact Assessment Interpretation (and Improvement) We’ll do a lot with #1, then #2, and come back to #2 at end of course Regardless, need to learn terminology first before doing anything else..

Components and Criteria Spatial, Temporal Design Functional unit Significance/magnitude Uncertainty ISO documents a framework (not a recipe); LCAs may or may not consider all points above

Criticisms / Limitations Data reliability and quality is questionable. Models based on assumptions. Problem boundaries are arbitrary. Scale issues - global -> local, etc. Uncertainty is everywhere Spatial and temporal issues Comparisons between studies difficult No single, accepted method

Important Note on Context LCA should be one part of a broad environmental assessment If comparing with LCA, all assumptions and methods should be consistent Especially problematic for validating against external studies

Definitions Big set of definitions in ISO framework documents (e.g., p.1 of ISO 14040) Won’t review all of them here, but you need to know them. Big ones to know are unit process, elementary flows, inputs, outputs

Definitions Elementary flows - material or energy entering or leaving the system, directly to/from the environment, without human transformation Unit process - smallest portion of a product being studied for which LCI data available Inputs / Outputs - materials or energy entering or leaving a unit process

Scope Considerations Setting all the parameters for study e.g., functional unit, boundaries, data, etc. Whether it will be critically reviewed May be iterative (update in progress) Supports product system diagram Realize LCA can be used for ‘products’, ‘processes’, ‘systems’, etc. Functional unit definition ensures unit consistency for validation and comparison

Product Systems Collections of unit processes, elementary flows, and product flows Also shows system boundary Processes, flows maybe in / out of bounds In: fuel, energy, materials, … Out: emissions, waste, …

Simple Example - Tree Sunlight O2 Environ- Energy CO2 Tree ment System? CO2 Tree Water Wood You might also recognize this as a process-flow diagram. Same thing. If we wanted to do a life cycle inventory of a tree, we could draw the boundary in one of several places

More Complex Example We manufacture a part for new automobiles and ship it in cardboard boxes Currently, we “ship and forget it” Generates significant box waste We want to reduce waste - how? What are tradeoffs?

Original System Energy Raw Mats, Energy Energy Unboxed Part Boxed Part Cardboard Manuf. Energy Raw Mats, Energy Energy Unboxed Part Part Boxed Part Manufacture System Transport/ Delivery Car Assembly Packaging Emissions, Waste Emissions, Cardboard Box Waste

Packaging Takeback System Energy Cardboard Manuf. Reused Box Transp/ Logistics Emissions Part Manuf. System Packaging Empty Box Transport/ Delivery Car Assembly Unboxed Part Emissions, (Less?) Cardboard Waste

Packaging Takeback System Our new system uses less cardboard Thus less waste, manufacturing impacts But uses more transportation to retrieve used boxes Thus more energy use, emissions Unclear whether this tradeoff is beneficial Perfect application for LCI/LCA

Example Goal/Scope Goal: “To determine whether the new system is better than the old” More detail: which inventory items? How to assess? Maybe air emissions, energy use, waste generated Would a better goal originally have been to do LCA of old system and suggest improvements? Scope: Fairly detailed description of both systems, items in/out of boundaries e.g., might exclude impacts of product (relevant?) But include packaging/logistics/reuse of systems

Next Step: Inventory In general, just “good research” “Look up the data, add it up” However, data availability varies widely Consider inputs, outputs of interest In: energy, resources, etc. Out: emissions, waste, etc. Also may be iterative Allocation an issue

Inventory Process Iterative Collect/validate Matching data with unit processes/ functional units/etc See “sample forms” on pp.16-20 of ISO 14041 PDF.

Allocation Hard to assign “one to one” linkages between units and inputs-outputs Need standard/specified way to distribute (allocate) them mass balance method Physical properties Economic value ratio? What allocations needed for packaging takeback system?

Inventory Interpretation How do results fit goal/scope? Assessment of data quality Sensitivity analysis on inputs/outputs

Data Sheet Exercise Break into small groups (2-3 max) Using samples provided (from ISO 14041) summarize data for: Getting to school Doing a homework assignment / writing a paper Reading a book chapter Something else similar

Impact Assessment We’ll come back to this later in course Classification Characterization Weighting (e.g. taking an inventory of various toxics, then weighted by toxicity) Assumed that existing weighting methods can be used (not developed as part of LCA)

Resources Don’t despair, you do not need to collect all of your own data for LCAs, for example: US NREL LCI Database (various): http://www.nrel.gov/lci/ BEES (construction materials): http://www.bfrl.nist.gov/oae/software/bees.html Slightly ahead of schedule in content, but you should look at these for ideas before finalizing ideas and scope for Course Project