How Green is That Product? An Introduction to Life Cycle Environmental AssessmentHomework #6Goals: In this assignment, youll do the following: address a multi-functionality issue by using the avoided burden approach; perform a data quality assessment of a published LCI study.Instructions: The questions below can be answered offline. When you complete the assignment, return to the Week 6 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.

Multi-functionality and the avoided burden approach Recall from Homework #5 that Table A contains representative facility energy use and production data for the commercial bakery example that weve discussed in the lectures. This time, assume that you dont have process-level data; thus, you cannot divide the facility into its sub-processes as you did in Homework #5. Instead, youll use the avoided burden approach to estimate the facility energy inputs that are associated with just the baked bread.

Table A: Energy and production data for a commercial baking facility

Production of baked bread (kg/year)500,000

Production of frozen dough (kg/year)400,000

Natural gas used to generate steam (TJ/yr)0.97

Natural gas used directly in baking ovens (TJ/yr)2.31

Electricity use (MWh/yr)461

Table C contains data on frozen dough production processes from another facility that manufactures only frozen dough. Table C: Process energy requirements for frozen dough production

ProductProcessSteam use (MJ/kg)Direct natural gas use (MJ/kg)Electricity use (kWh/kg)

Frozen doughMix - - 0.10

Form and chill0.37 - -

Bake0.400.800.05

Cool - - 0.54

Finish - - 0.09

Package - - 0.15

Your job is to use the avoided burden approach based on the information in Tables A and C to assign the commercial bakerys inputs of natural gas (for steam), natural gas (direct use), and electricity to just the baked bread. Enter your results below. For all answers, enter only the numerical value using two decimal places after the decimal separator (i.e., X.XX). (8.33 points for each correct answer)Question 1: How much of the facilitys annual natural gas use for steam is attributable to just the baked bread? Use units of TJ/year in your answer.

Question 2: How much of the facilitys annual direct natural gas use is attributable to just the baked bread? Use units of TJ/year in your answer.

Question 3: How much of the facilitys annual electricity use is attributable to just the baked bread? Use units of MWh/year in your answer.

Now, compare your answers above to Answers 6, 7, and 8 from Homework 5. T hen, answer the following questions (5 points for each correct answer):Question 4: Compared to Homework 5, Answer 6, does the avoided burden approach overestimate or underestimate the annual natural gas use for steam that is attributable to just the baked bread? Overestimate UnderestimateQuestion 5: What is the percent difference between Answer 1 (above) and Answer 6 (Homework 5)? Chose the closest answer. Hint: Calculate the percent difference as (Answer 1 Answer 6)/(Answer 6)*100. 12% -42% 2% -21% -88%Question 6: Compared to Homework 5, Answer 7, does the avoided burden approach overestimate or underestimate the annual direct natural gas use that is attributable to just the baked bread? Overestimate UnderestimateQuestion 7: What is the percent difference between Answer 2 (above) and Answer 7 (Homework 5)? Chose the closest answer. 25% -5% -23% 42% 11%Question 8: Compared to Homework 5, Answer 8, does the avoided burden approach overestimate or underestimate the annual electricity use that is attributable to just the baked bread? Overestimate UnderestimateQuestion 9: What is the percent difference between Answer 3 (above) and Answer 8 (Homework 5)? Chose the closest answer. -46% 75% -50% 50% -42%

Data quality assessment (5 points for each correct answer)To answer these questions, youll need to first download and read the following article:Aldo Roberto Ometto, Michael Zwicky Hauschild, Woodrow Nelson Lopes Roma (2009). Lifecycle assessment of fuel ethanol from sugarcane in Brazil. The International Journal of Life Cycle Assessment, May 2009, Volume 14, Issue 3, pp 236-247.http://users.ugent.be/~jdewulf/Rodrigo%20Alvarenga/Ometto%20et%20al%202009.pdf Refer to the Week 17 lecture notes and review the Pedigree matrix with 5 data quality indicators table from Weidema and Wesnaes (1996). Your job is to read the above article and assess the overall temporal correlation of all the data used for each unit process by giving the unit process inventory a single score from 1 to 5 based on the guidance in the pedigree matrix. Note that the year of the authors analysis as stated in the paper is 2008. Important: further note that they have obtained primary data for the years 2001-2008 for some of their foreground data; for the purposes of this assignment, treat those primary data as having less than 6 years difference from 2008 for the purpose of scoring their temporal correlation, since these data are an average of a 7 year period that extends up to the data of their analysis. Note that they mix primary data and secondary data in each unit process inventory; the primary data are reported without a source, and the secondary data are reported with a source.Also, use the following simplifying assumptions:When a publication is cited for particular data, assume that the year of publication is the same as the year of the data within that publication (this is certainly not always the case, but a necessary shortcut for us in this assignment since we dont have access to all cited sources)If 2008 the year of the data = 6 or less, choose less than 6 years differenceIf 2008 the year of the data = 10 or less, choose less than 10 years differenceIf 2008 the year of the data = 15 or less, choose less than 15 years differenceIf 2008 the year of the data = greater than 15, choose more than 15 years difference(These data year simplifications are needed because we dont have the months and the years of publication for cited data, we just have the years. However, a study published in December 1998 is less than ten years prior to January 2008, so even though 2008-1998 = 10, the study could be less than 10 years old.)Enter your answers in the boxes below. (Hint: take a conservative approach! If there are multiple years of data for the non-primary data that have been used in a given unit process inventory, use the oldest year to assign your single score for that unit process inventory.)QuestionUnit process inventoryYour score for temporal correlation to 2008

10Unit Process 1: Soil preparation

11Unit Process 2: Sugar cane plantation

12Unit Process 3: Chemicals application

13Unit Process 4: Harvesting

14Unit process 5: Fuel hydrated ethanol industrial process

15Unit process 6: electrical energy cogeneration

16Unit process 7: irrigation

17Unit Process 8: Ethanol distribution

18Unit Process 9: Use of fuel ethanol