-
8/12/2019 13 11 Deidre Wolff
1/19
Comparative Analysis of Life Cycle Inventory
Techniques and Development of a QuantitativeUncertainty Analysis Procedure
Deidre Wolff
School of Civil and Building Services Engineering
Prof. Aidan DuffyProf. Geoff Hammond
Nov. 29, 2013
-
8/12/2019 13 11 Deidre Wolff
2/19
Life Cycle Assessment (LCA)
The compilation and evaluation of the inputs,
outputs, and potential environmental impacts of
a product system throughout its life cycle
(ISO 14044, 2006)
-
8/12/2019 13 11 Deidre Wolff
3/19
7
Life Cycle Assessment (LCA)
Four Stages:
Goal and Scope Definition
Life Cycle Inventory (LCI)
Life Cycle Impact
Assessment (LCIA)
Interpretation
(ISO 14040)
GoalDefinition and
Scope
InventoryAnalysis
Interpretation
ImpactAssessment
-
8/12/2019 13 11 Deidre Wolff
4/19
Motivation
LCA is often used in decision-making processesand to inform policy
LCA involves using expert judgement,
assumptions, data of poor quality, allocationand weighting
These all introduce uncertainty
Uncertainty is often ignored in LCA studiesdue to lack of knowledge and/or time and
budget constraints
-
8/12/2019 13 11 Deidre Wolff
5/19
-
8/12/2019 13 11 Deidre Wolff
6/19
What is uncertainty?
Errors originating from inaccurate
measurements, lack of data, and model
assumptions (Huijbregts, 1998)
The problem of using information that is
unavailable, wrong, unreliable, or that shows acertain degree of variability (Heijungs, 2004)
-
8/12/2019 13 11 Deidre Wolff
7/19
Uncertainty Classification in LCA
Parameter
data uncertainty
arises due to incomplete knowledge of true value of data, lack of data
or measurement error
Model
unknown interactions between model formulations, due to
simplification, derivation of characterization factors, aggregation of
data into impact categories
Scenario
due to decisions made during the LCA, such as choice in system
boundary, functional unit, allocation, weighting factors
-
8/12/2019 13 11 Deidre Wolff
8/19
LCA Overall Steps...
Goal and Scope LCI LCIA Interpretation
System
Boundary
Weighting
Methods
Characterization
Factors
ChooseImpact
Categories
Uncertainty
Analysis
Contribution/
Sensitivity
Analysis
Identify
Significant
Issues
FU and
Reference
Flow
Allocation
Procedure
LCI/LCIA
Method
Assumptions
Scale Data to
FU/ Ref Flow
Data
Collection
-
8/12/2019 13 11 Deidre Wolff
9/19
(Reap et al, 2008)
-
8/12/2019 13 11 Deidre Wolff
10/19
Case-study: Process LCA
Goal and Scope:
Determine the overall Global WarmingPotential for the production of an electric kettle,using data from EcoInvent Database.
System boundary is cradle-to-gate, includingraw material extraction and manufacturing ofthe materials used for the production of a kettle.
The system boundary is simplified, as theoverall goal of the LCA is to quantify theuncertainty.
-
8/12/2019 13 11 Deidre Wolff
11/19
RawMaterial
Extraction
Transport toproduction
facility
Assembly of
Electric Kettle
Energy Input Energy Input
Emissions to Air Emissions to Air
Transport of
Electric Kettle
to Consumer
Energy Input
Emissions to Air
Energy Input
Emissions to Air
Disposal/
RecyclingUse Phase
Energy InputEnergy Input
Emissions to Air Emissions to Air
Case-study: Process LCA
-
8/12/2019 13 11 Deidre Wolff
12/19
System Diagram
Stainless
Steel
Poly-
propylen
e
Silicone
Poly-
propylene
Copper
Polyamide
Electrical
Component
Body ofKettle
Stainless
Steel
KettleAssembly
437 g
0.4 g
245.5 g 682.9g
1038.5 g
355.6 g
3.5 g
41.9 g
310.2g
15 g
The emissionsassociated with energyconsumed during these
steps has been ignoredfor simplification
-
8/12/2019 13 11 Deidre Wolff
13/19
Process LCI and LCIA ResultsEmissions to Air Quantity Unit Total Characterization Factor CO2-equivalents
CO2 Biogenic HPD 2.79E-02 kg 3.16E-02 1 3.16E-02
CO2 Biogenic LPD 2.58E-03 kg
CO2 Biogenic Unspecified 1.13E-03 kg
CO2 Fossil lower strat and upper tro 3.52E-08 kg 2.94E+00 1 2.94E+00
CO2 Fossil unspecified 3.23E-01 kg
CO2 Fossil HPD 2.16E+00 kg
CO2 Fossil LPD 4.57E-01 kg
CO2 Land Transformation, LPD 4.49E-05 kg 4.49E-05 1 4.49E-05
SF6 LPD 4.16E-11 kg 3.65E-08 22800 8.33E-04
SF6 Unspecified 3.65E-08 kg
N2O LPD 7.46E-06 kg 4.19E-05 298 1.25E-02
N2O lower strat and upper trop 3.36E-13 kg
N2O HPD 2.67E-05 kg
N2O Unspecified 7.77E-06 kg
Methane biogenic LPD 8.20E-06 kg 5.40E-05 25 1.35E-03
Methane biogenic HPD 2.72E-05 kg
Methane biogenic Unspecified 1.86E-05 kg
Methane fossil LPD 4.78E-03 kg 1.15E-02 25 2.87E-01
Methane fossil lower strat and upp 5.60E-13 kg
Methane fossil HPD 6.68E-03 kg
Methane fossil Uspecified 3.57E-06 kg
CF4 HPD (PFCs) 2.28E-11 kg 2.29E-07 7390 1.69E-03
CF4 Unspecified (PFCs) 2.29E-07 kg
C2F6 HPD (PFCs) 2.03E-10 kg 2.57E-08 12200 3.13E-04
C2F6 Unspecified (PFCs) 2.55E-08 kg
CHF3 HPD (HCFCs) 8.11E-12 kg 8.11E-12 14800 1.20E-07
Total GWP: 3.277
LCIALCI Data
-
8/12/2019 13 11 Deidre Wolff
14/19
Contribution Analysis
-
8/12/2019 13 11 Deidre Wolff
15/19
Contribution Analysis
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
Polypropylene Stainless Steel Silicone
ContributiontoOverallGWP
(%)
Contribution of Body Component Material toOverall GWP
Methane (Fossil HPD)
Methane (Fossil LPD)
CO2 (Fossil LPD)
CO2 (Fossil HPD)
CO2 (Fossil Unspecified)
-
8/12/2019 13 11 Deidre Wolff
16/19
Sensitive Parameters
Sensitive Parameter
Contribution toOverall GWP
(%)
Mean Value (kgCO2-eq per
Kettle)
Raw EcoInvent Data
Emission
Kettle Part
and
Material
Mean (kg) Minimum (kg)Maximum
(kg)
CO2(Fossil) Electrical,Polyprop.
15.9% 0.519 1.673 1.670 1.676
CO2(Fossil)Body,
Polyprop.12.6% 0.410 1.673 1.670 1.676
CO2(Fossil)
Body,
Stainless
Steel
56.5% 1.842 4.212 3.673 4.865
-
8/12/2019 13 11 Deidre Wolff
17/19
Sensitivity Analysis
-
8/12/2019 13 11 Deidre Wolff
18/19
Next Steps
Quantify Uncertainty
Identify scenario and model uncertainty
Is it necessary to quantify scenario and model
uncertainty in all cases?
-
8/12/2019 13 11 Deidre Wolff
19/19
Thank You!
Any Questions?
