How Green is That Product? An Introduction to Life Cycle Environmental Assessment

Homework #8

Goals: In this assignment, youll do the following:

conduct the life-cycle impact assessment (LCIA) step for your bottled soft drink LCA using TRACI;

and

generate and interpret a contribution analysis of your LCIA results.

Instructions: When you complete the assignment, return to the Week 8 course page on the Coursera

website. Click on the Submit Homework Assignment Answers button, which will allow you to enter

your answers into a web form for automated grading.

Grading: This assignment is worth 100 points. The point values of each answer are listed below. You

can submit a maximum of 30 attempts. The highest scoring attempt that is submitted before the

deadline will count toward your official grade. Scores for each attempt will be available immediately

after submission of your answers.

Numbers: In this assignment, and throughout this course, numbers will be expressed using the U.S.

numeric convention where commas separate thousands and the dot (or decimal point) is the decimal

separator. For example, the number one thousand two hundred and one-tenth is written 1,200.1.

Life-cycle impact assessment (LCIA) using TRACI (5 points for each correct answer)

The Week 8 version of the bottled soft drink LCA contains the final and complete life-cycle inventory

(LCI). Your job is to now conduct the life-cycle impact assessment (LCIA) step, using characterization

factors from the U.S. EPAs Tool for the Reduction and Assessment of Chemical and Other Environmental

Impacts (TRACI). These characterization factors can be observed on the TRACI tab in the Week 8

version of the bottled soft drink LCA spreadsheet file.

Using your final LCI results and the TRACI characterization factors, complete the TRACI Results tab in

your project spreadsheet. Use the Week 8 version of the HDPE grocery bag LCA spreadsheet as a helpful

example. When youve completed the TRACI Results tab, enter the category indicator results you

obtained into the table below.

When completing this task, please do the following:

1. Assume that all air emissions occur in urban areas, just as we did in the Week 8 version of the

HDPE grocery bag LCA spreadsheet.

2. Calculate the grand totals for the eutrophication, ecotoxicity, human health cancer, and

human health non-cancer impact categories by adding the results for air and water into one

grand total. Note that TRACI category indicator results for a given impact category can be

summed across emissions media, which is what we are asking you to do here. Refer to the

Contribution I tab of the Week 8 version of the HDPE grocery bag LCA spreadsheet file to

observe how we simply summed up air results and water results for these impact categories into

grand totals for the calculations in our contribution analysis. Note that you may have to

unhide some columns on the Contribution I tab.

Note: All answers should use the following format X.XXE-XX. However, the E-XX term has already

been provided for you for each answer. Thus, you only need to enter the X.XX portion of the number

in each answer box. For example, if the category indicator result for global warming is 3.22E-01, just

enter 3.22 into the shaded answer box in Table 1; the E-01 term has already been provided for you.

TRACI category indicator results (X.XXE-XX)

Impact category (units) Total (X.XX) Total (E-XX) Question

Global Warming Air (kg CO2 eq) E-01 1

Acidification Air (kg H+ moles eq) E-02 2

Human Health Criteria Air (kg PM10 eq) E-04 3

Eutrophication total (air + water) (kg N eq) E-05 4

Ozone Depletion Air (kg CFC-11 eq) E-10 5

Smog Air (kg O3 eq) E-02 6

Ecotoxicity total (air + water) (PAF.m3.day) E-01 7

Human health - cancer total (air + water) (cases) E-10 8

Human health - non-cancer total (air + water) (cases)

E-09 9

Contribution analysis (6 points for each correct answer 10-17; 7 points for answer 18)

Using your LCIA results in Table 1, construct a contribution analysis for each TRACI impact category by

unit process in your bottled soft drink life cycle. Follow the format thats been provided for you on the

Contribution I tab of the Week 8 version of the HDPE grocery bag LCA spreadsheet file. Your

contribution analysis table should list your 21 bottled soft drink life cycle unit processes in rows, the 9

impact categories in columns, and the percent contribution of each unit process to each impact category

in the cells. When youve completed this task, enter the name of the unit process that makes the

greatest contribution to each impact category into the table below. Note that your contribution analysis

should be based on the grand totals (air results + water results) for eutrophication, ecotoxicity, human

health-cancer, and human-health non-cancer. This is the same approach as we used on the

Contribution I tab of the Week 8 version of the HDPE grocery bag LCA spreadsheet file. Refer to that

file for guidance. Note that you may have to unhide some columns on the Contribution I tab.

Greatest contributing unit processes by impact category

Impact category Unit Process Question

Global warming 10

Acidification 11

Human health criteria 12

Eutrophication total 13

Ozone depletion 14

Smog 15

Ecotoxicity total 16

Human health - cancer total 17

Human health - non-cancer total 18