Goal and scope definition

1
Life Cycle Inventory Analysis III
Goal and scopedefinition
Interpretation
Inventoryanalysis
Impactassessment
2
Inventory AnalysisSystem boundaries
In LCA inventory analysis 3 types of boundaries
can be distinguished 1. the boundary between the
product system and the environment system 2. the
boundary between Flows and processes that are
relevant and irrelevant for the product
system (cut-off) 3. the boundary between the
product system under consideration and other
product systems (allocation) Ad 1. Human
control over processes is the main criterion for
regarding a process as a unit
process, hence including it in the product system
(how about landfills?). Ad 2. - Cut-off is
necessary mainly for reasons of lack of data,
time and money - Cut-off is more than
simply ignoring certain parts, the estimation of
lacking data is essential.
- Possible guideline Processes that contribute
less than X of the total inputs
or outputs can be excluded from the
study (ISO14041, Section 3.1) -
Example In many LCAs production and maintenance
of production equipment
is omitted (how about agricultural
machinery?) Ad 3. Allocation is the result of
the multi-functionality (also called
co-production) of an economic process
and is performed at the unit process level
3
Allocation by avoided burden approach
The system is expanded to include additional
burdens of co-product processing and the avoided
burdens of any avoided processes
Vehicle production v
Vehicle
Vehicle life cycle
Recycling process r
Primary production p
Building production b
Building
Building life cycle
Environmental burdens of the vehicle
Ev Er Ep
4
A closer look at the avoided burden method
Vehicle
600 kg
BF/BOF (2.2 kgCO2/kg)
Vehicle Life Cycle
600 kg
EAF (0.6 kgCO2/kg)
600 kg
Building Life Cycle
BF/BOF (2.2 kgCO2/kg)
600 kg
Building
Credit for scrap generation requires debit for
scrap use!
5
The avoided burden principle credit debit
The system is expanded to include additional
burdens of co-product processing and the avoided
burdens of any displaced processes
Vehicle production v
Vehicle
Boundaries of original system
Recycling process r
Primary production p
Building production b
Building
Boundaries of expanded system
Environmental burdens
Vehicle Building Ev Er Eb
Vehicle Ev Er Ep Ev (Ep Er)
Credit
Building Ep Eb Er Eb (Ep Er)
Debit
6
Material Recycling Recycled Content vs. Avoided
Burden
Recycled Content
Avoided Burden
1
A
Prim
Sec
0.75
0.25
Prim
B
Sec
0.75
0.25
Prim
C
1
7
More allocation methods for material recycling
100 Recycled Content
100 Avoided Burden
50 / 50
Average (n3,r0.75)
8
Allocation methods for material recycling
Product A
Primary production
0 recycled content 100 end-of-life recycling
Recycling
Product B
100 recycled content 100 end-of-life recycling
Recycling
Product C
100 recycled content 0 end-of-life recycling
Disposal
9
Allocation methods for material recycling
Product A
Primary production
0 recycled content 100 end-of-life recycling
Recycling
Product B
100 recycled content 100 end-of-life recycling
Recycling
Product C
100 recycled content 0 end-of-life recycling
Disposal
10
Allocation methods for material recycling
Product A
Primary production
0 recycled content 100 end-of-life recycling
Recycling
Product B
100 recycled content 100 end-of-life recycling
Recycling
Product C
100 recycled content 0 end-of-life recycling
Disposal
11
A closer look at the avoided burden approach
Observation 1 There are three types of causality
involved in the approach
Production ofthe necessarymaterial
Futurecollection reprocessing
Avoided materialproduction disposal
Involved processes


Type of causality
Factual
Probabilistic
Counterfactual
Observation 2 Recycling does not automatically
displace primary production

• Collected scrap can
• displace metal from primary production
• displace scrap collection and recycling
  elsewhere
• displace other materials (primary or secondary)
• increase market demand (i.e. not displace
  anything)

12
Attributional versus Consequential LCA Definition
Attributional LCA Quantify the environmental
Impacts generated by a product system (in a given
state).
Example Production of X cars
Use
Eol
Production
Consequential LCA Quantify the environmental
Impacts generated by a change in the product
system.
Example Additional production of ?X more cars
Additionaleol
Additionaluse
Additionalproduction
13
Attributional versus Consequential LCA Inventory
Data
Attributional LCA Process inventories based on
average data
Production
Consequential LCA Process inventories need to
reflect the impact of the output change
Production
Same as
?
14
Attributional versus Consequential LCA Allocation
Attributional LCA How to deal with intermediary
flows crossing the system boundary?
Eol
Use
Production
Consequential LCA Account for all significant
changes that results from the initial change in
the product system.
Additionaleol
Additionaluse
Additionalproduction
Additionalrecycling
Note This is why the avoided burden approach
is consequential system expansion.
Displacedproduction
15
The computational structure of process LCI 1
One way to describe a unit process is the
following vector
with
16
The computational structure of process LCI 2
Assume that the product system is described by
The product system can now be represented by the
following two matrices
Columns are processes
Rows are intermediary flows (in mass, volume or
energy content)
Rows are elementary flows (in mass, volume and
energy content)
17
The computational structure of process LCI 3
The economic part of the process matrix
multiplied by a vector of activity levelsequals
the output vector of the product system
Example
output vector
18
The computational structure of process LCI 4
The environmental part of the process matrix
multiplied by a vector of activity levelsyields
the life cycle inventory of the product system
Example
life cycle inventory
19
The computational structure of process LCI 5
To calculate the LCI of a product system
generating a given reference flow,we first
calculate the required process activity levels,
and multiply the vector of activity levels with
the matrix of elementary flows
The LCI of a product system can thus be
calculated as
20
The computational structure of input-output LCI 1
Here the product system is modeled using an
economic input-output table
Columns a industrial sectors
Rows a the sameindustrial sectors
This is the input (in ) from sector c required
to produce 1 of output from sector a.
21
The computational structure of input-output LCI 2
Output vector
Input vector
x

input of producers output of 1st tier suppliers
22
The computational structure of input-output LCI 3
Input vector
Output vector
x
x

input of producers output of 1st tier suppliers
input of 1st tier suppliers output of 2nd tier
suppliers
23
The computational structure of input-output LCI 4
Step 1 Calculate the total output required to
generate producers output
Step 2 Convert the total output (given in )
into environmental impacts
etc.
24
The computational structure of process LCI
Example
Product system Production, use and disposal of
aluminum packaging Reference flow 10 packages
25
The computational structure of process LCI
Example, cont.
26
Reading for Monday, 4 February Guinée J B
(Ed.) (2002) Handbook on Life Cycle Assessment,
Operational Guide to the ISO Standards, Kluwer,
Dordrecht, The Netherlands Part 3 Scientific
Background, Chapter 4 Impact Assessmentpp
136-147 Sections 4.1 and 4.2 pp 241-252
Sections 4.4 to 4.8 pdf available on course
websitehttp//www.bren.ucsb.edu/academics/course
.asp?number282