Life Cycle Assessment: The ABC’s

1. Life Cycle Assessment:The ABC’s H. Scott Matthews Civil and Environmental Engineering Carnegie Mellon University

2. Goal of Course • Simply put, the goal is to change forever the way you think about products and systems • Hard but achievable • No more errors in ignoring the whole life cycle

3. A - 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?

4. Allocation (cont.) • Ideally, avoid it • Separate into subprocesses • Divide and conquer (only allocate from 1) • Example: CMU produces 30 CEE graduates per year. How to model student production of the university? • There are ~30 departments, assume each produces one? • One of the 30 departments is CEE, and produces all of the graduates • This sounds trivial, but is a common mistake! Source: ISO 14041, Appendix B

5. Allocation Rules (cont.) • Else expand system boundaries! • Allocate by physical relationship • Allocate incinerated waste emissions of cadmium only to waste products containing cadmium • Mass or volume for transport allocation • See other examples in ISO 14041, App B

6. sub-system2 process process process process process process process process process process process process process process process process process process process process process sub-system1 Structure of a Process-based LCA Model

7. B - The Boundary Issue • Where to set the boundary of the LCA? • Include all processes, but at least the most important processes if there are time and financial constraints • Which are the least and most important? • Often do not know until you’re done! • Draw boundaries around processes, number of flows tracked, life cycle stages, time, ..? • Maybe combinations of the above

8. RESOURCES waste system boundary C - Circularity Effects • Circularity effects in the economy must be accounted for: cars are made from steel, steel is made with iron ore, coal, steel machinery, etc. Iron ore and coal are mined using steel machinery, energy, etc... product emissions

9. Special Notes - Public Studies • Follow ISO-prescribed format on reporting the results • Use external peer-reviewers to ensure validity • Incorporate, as necessary, comments of reviewers • Much like an academic journal publication process! • Be careful with comparative assertions (i.e., “A is better than B”) • Cannot just use LCIA results, weighting methods

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

11. Reporting • Need to document everything you’ve done, especially assumptions. • See ISO 14041 document (Section 8)

12. “Process-based” Resources • US NREL LCI Database (free): • http://www.nrel.gov/lci/ • BEES (construction materials): • http://www.bfrl.nist.gov/oae/software/bees.html • Athena • Swiss ecoinvent ($1500) • http://www.ecoinvent.ch/en/index.htm • SimaPro ($2000-$4000 per license) • GaBi ($1000-$3000 per license) • Most “tools” are Euro-centric

13. Data Sources - Heart of Tools • All ‘tools’ are ‘front ends’ to databases • The data is the important part • The interface is just there to help • Should examine data documentation to guide you towards what you need

14. Ecoinvent query / results • Let’s look at the metadata for the ecoinvent database, available for free • The actual flow data is not free • Portland cement • Look at metadata - what is included? Scope? Assumptions? Source? Location? • What could you use it for?

15. Some notes from NREL LCIDatabase User’s Guide • Four kinds of LCI data on flows: • Inputs from technosphere (other processes) • Inputs from nature • Outputs to nature • Products / co-product outputs (not to nature) • Provides allocated and unallocated data • unallocated better - can allocate yourself • Scopes vary (cradle to gate/ gate to gate) • Imagine all of this data “in a database” with front end -> you have a US LCI tool.

16. Using the NREL LCI Database • Look at User’s Guide on website • Understand terminology and flows • Download some spreadsheets to see what they look like

17. Look at Coal and Electricity Generation data (handout)

18. Energy Balance for Typical Coal Plant http://www.energy.qld.gov.au/electricity/infosite/elec&env7/roleofenergy7_3/efficiencyinpowerstat/energylosses/energylosses.htm Energy Balance for Typical Coal Plant

19. Question 1:Simple Coal LCI • Just use information from previous slide, and provided information (from NREL database) on coal production and combustion @ utility • What is total energy (GJ) required to make electricity? • Conversions: 1 lb coal ~ 12000 BTU • 1 BTU =1054 Joule; • Gasoline ~ 125000 BTU/gallon • Distillate (e.g., diesel) ~ 135,000 BTU/gallon • Residual ~ 150,000 BTU/gallon • 1 ft^3 of natural gas ~ 1000 BTU • Truck transportation ~2500 BTU/ton-mile

20. Now.. • Can we now follow how the NREL inventory for “Electricity Generation” comes from? (given our insights on coal) • Start by drawing your product-system diagram, with key processes/modules (relating of course to data you have) • What is your boundary?

21. NREL Data Comparison • Let’s look at NREL data for CO2 and energy effects from shipping stuff • Note a ton-mile = 1 ton shipped 1 mile • Like a kiowatt-hour (kWh) • What are impacts for boat, rail, truck, air? • Does their order make sense?

22. CO2 per 1000 ton-miles • Air - 169 lbs CO2 • Combination truck - 257 • Rail - 61 • Ocean - 46 • What does this tell us?

23. Issues with LCI Databases • Sources? • Assumptions - what needed to use them? • How do they link with other data sources, internally and externally? • What else came up from exercises today?

24. Next Time • Streamlined LCA • Demo of Process-based tool, database