Reuse and Recycling: From Supply Chains to Supply Loops

1
Reuse and RecyclingFrom Supply Chains to Supply
Loops
2
Assignment 3 due Wednesday 28 February!
Lecture 13 Monday, February 26
cancelledLecture 14 Wednesday, February 28
cancelled Make-up class Friday, March 9, 830
945 Make-up class Friday, March 16, 830
945Next ClassMonday, March 5 Guest
speaker Stephen MacIntosh,
Environmental Services Supervisor, City of Santa
Barbara
3
Supply Loops
Reuse and recycling Environmental benefits
1-R
1-R
Production Eprod
End-of-life disposal Edisp
Use Euse
R
R
Collection Ecoll
Reprocessing Erepro

• Diversion of product or process waste from
  landfill or incineration by collecting them for
  economic value recovery via reprocessing.
• Generation of secondary resources from product
  or process waste and displace primary
  resources, i.e. materials, components and
  products.

Change in total environmental impact due to
recycling/reuse ?E Ewith Ewithout
R(Erepro Ecoll Eprod Edisp
) Recycling/reuse reduces life cycle impact if ?E
lt 0, i.e. Erepro Ecoll lt Eprod Edisp
4
Case study Recycling and reuse of structural
steel sections in construction
5
Case study Recycling and reuse of structural
steel sections in construction
Environmental evaluation of supply loops for
steel sections
Factor 2
Factor 5
6
Supply Loops
Materials recycling Basic environmental
performance
GJ / ton
Example Recycling of steel sections ?E
R(Erepro Ecoll Eprod Edisp )
R(17.6 0.4 35.3 1.3) GJ / ton - R18.6
GJ / ton
In this linear model, increasing the recycling
rate decreases environmental impact.
7
Supply Loops
Materials recycling Constrained environmental
performance
GJ / ton
Example Recycling of steel sections ?E
R(Erepro(R) Ecoll(R) Eprod Edisp )
R(R30 35.3 1.3) GJ / ton
If Ecoll , Erepro or both are increasing
functions of r, then the lowest environmental
impact may be reached for collection rates lower
than 1.
8
Case study Reusing Components in Durable Goods
Model
Product demand use
Product manufacturing Eman
1-rc
1-c
rc
c
Eol product collection insp. Ecoll
End-of-life product disposal Edisp
Product remanufacturing Ereman
rc
(1-r)c

• Environmental impact
• Without reuse Eman Edisp
• With reuse (1-rc)Emanrc Ereman c Ecoll
  (1-rc) Edisp
• Change in environmental impact
• ?E rcEman rcEdisp - rcEreman - cEcoll
  gross reduction - additional
  impact
• c collection rate, r reuse yield, product between
  c and r is reuse rate rc

9
Supply loop constraint Limited component
durability
10
Supply loop constraint 1 Limited component
durability
Example Average number of lives n 3
Collection rate c 0.1 Total collected
111 Total reused 110
1
Reuse yield r
Collection rate c
1
11
Supply loop constraint 1 Limited component
durability
Example Average number of lives n 3
Collection rate c 0.5 Total collected
875 Total reused 750
1
Reuse yield r
Collection rate c
1
12
Supply loop constraint 1 Limited component
durability
Example Average number of lives n 3
Collection rate c 0.9 Total collected
2439 Total reused 1710
1
Reuse yield r
Collection rate c
1
13
Limited component durability impacts technical
feasibility of reuse
Reuse rate rc is now a non-linear function of
the collection rate c and the average number of
lives n
14
Total environmental impact is a non-linear
function of the collection rate c
Beyond a certain collection rate environmental
impact starts to increase again.
15
Conclusions
In supply loops the additional environmental
impacts ofcollection and reprocessing need to be
traded off against the saved environmental
impacts of primary production and disposal. In
constrained supply loops more is not always
better. Supply loops may haveenvironmentally
optimal collection rates anywhere between 0 and
100.

• In supply loops, the environmental impacts of all
  processes need to be assessed and managed in an
  integrated way withthe following four issues
• the access to product and process waste
• the feasibility of their reprocessing
• the demand for the resulting secondary resources
• the displacement of primary resources

16
Case study Iron and Steel in the UK

• Scope and system boundaries
• Document and analyze the iron steel flows of
  the UK from 1970-2000
• Calculate the current recycling rate
• Boundaries of the material stocks are the
  geographical borders of the UK
• Account for trade

• Process groups
• Production (integrated steelworks, EAF mills,
  foundries)
• Fabrication and manufacturing (component and
  product manufacturing)
• Use

• Material categories
• Iron ore Primary resource for iron and steel,
  average crustal abundance around 5.8
• Iron and steel scrap - Home scrap (generated
  at iron and steel foundries and mills) -
  Prompt or new scrap (generated during fabrication
  and manufacturing) - End-of-life or old scrap
  (generated when iron and steel containing goods
  leave the use phase)
• Iron and steel industry products (e.g. castings,
  ingots, billets, rods, bars, sections,
  plates, strip, sheet, etc.)
• Iron and steel contained in new final goods (
  of iron and steel in goods)

17
Case study Recycling Rate of Iron and Steel in
the UK
Material and process flow model of the UK iron
and steel cycle
Trade
Trade
Trade
Iron steel products
Iron steel in new goods
Iron ore
Production
Use
Fabrication manufacturing
C
Iron steel scrap
TSG
Loss
Ex
Im
UK border
Trade
18
Case study Recycling Rate of Iron and Steel in
the UK
Ex
Im
C
TSG
19
Case study Recycling Rate of Iron and Steel in
the UK
20
Case study Recycling Rate of Iron and Steel in
the UK
21
Case study Recycling Rate of Iron and Steel in
the UK
I S in new final goods entering use in the UK
22
Case study Recycling Rate of Iron and Steel in
the UK
23
Case study Recycling Rate of Iron and Steel in
the UK
Total scrap generation versus actual scrap
consumption
24
Case study Recycling Rate of Iron and Steel in
the UK
Results and sensitivity analysis