Life cycle assessment studies of tablet PCs
Paul Teehan
-- paul.teehan@gmail.com
PhD Candidate
Institute for Resources, Environment and Sustainability
University of British Columbia
Green Electronics Council Slates/Tablets workshop
Dallas, TX, Dec 12, 2013
Outline
• Review of LCA studies of tablets
• In-depth study of embodied CO2 of Apple iPad
and comparison against other electronics
• Summary and research outlook
Review of existing LCA studies
Important caveats
•
LCA studies are highly sensitive to internal study assumptions, data
sources, variations in processes and products under study, omissions of
unknown but high-impact materials, etc.
•
Comparisons of one study to another are therefore generally not valid
(apples/oranges problem) unless the studies are carefully adjusted
•
Studies rarely include enough information to facilitate such adjustments
•
LCA is a data-starved field; researchers rely on ‘best-fit’ proxy models
which may be a decade old or more; all numbers are very uncertain
•
Accurately comparing numbers from different studies is therefore difficult.
Buyer beware.
Existing LCA studies of tablet PCs
• Industry studies
– Apple product environmental reports
– Dell carbon footprint study
• Academic studies
– Teehan & Kandlikar 2013: embodied CO2 of several electronic devices
including iPad (1st gen)
– Moberg et al 2010: LCA of newspaper reading on e-ink device
– Achachlouei et al 2013 – extensions of Moberg et al
Impacts of e-ink tablet per reader per year (2010 study)
* Production GHG: 8kg CO2-eq / yr
Negligible use impacts (e-ink)
Non-CO2 dimensions follow similar trends
*
Moberg, Åsa, Martin Johansson, Göran Finnveden, and Alex
Jonsson. “Printed and Tablet E-paper Newspaper from an
Environmental Perspective — A Screening Life Cycle
Assessment.” Environmental Impact Assessment Review 30,
no. 3 (April 2010): 177–191. doi:10.1016/j.eiar.2009.07.001.
Dell study – 5” Streak tablet (2011)
Total life cycle footprint: 45 kg CO2-eq (US)
2-year use lifespan
22kg CO2-eq production, 18kg CO2-eq use
Most use energy is in the
maintenance-no-load
charge mode
Special thanks and congratulations to Apple for their
industry-leading product environmental reports
www.apple.com/environment/reports/
Apple product environment reports, 2013
Product carbon footprint (kg CO2-eq)
400
350
300
250
Recycling
200
Transport
150
Use
100
Production
50
0
iPad Mini
iPad 2
iPad Mini iPad Air 11-inch 13-inch
w/ Retina
Macbook Macbook
Air
Air
In-depth study and comparison of embodied CO2 emissions
Teehan, P., and M. Kandlikar. “Comparing Embodied Greenhouse Gas Emissions
of Modern Computing and Electronics Products.” Environmental Science &
Technology 47, no. 9 (May 7, 2013): 3997–4003. doi:10.1021/es303012r.
Open access, available online: http://pubs.acs.org/doi/full/10.1021/es303012r
100% of raw data and analysis freely provided in Supporting Information
Study goal: estimate embodied CO2 of 11 devices
Method: Process-sum LCA with ecoinvent 2.2 data
Netbook
LCD monitor (21”)
iPad (1st gen)
Desktop (tower)
Desktop (small)
iPod touch (3rd
gen)
Thin client
Kindle (3rd gen)
Laptop
Rack server
Network switch
“Embodied CO2”: Everything before end transport, use, end-of-life
Includes all extraction, processing, etc, via ecoinvent models
LCD monitor (21”)
Netbook
iPad (1st gen)
Desktop (tower)
Products
Desktop (small)
iPod touch (3rd
gen)
Thin client
Kindle (3rd gen)
Laptop
Rack server
Network switch
Parts
listing
Impact
data
kg CO2-eq
Via hand disassembly
and weighing
Model products in terms of components and
materials in ecoinvent 2.2 database
Result: embodied greenhouse gas emissions
Characteristics of tablets
• Highly integrated; tiny circuit boards with few IC’s
– Key difference from netbooks and laptop
• IC’s tend to be advanced Systems-on-Chip with stacked die –
large source of impact
• Display module a large impact source as well
– No publicly available studies of Retina displays yet, but Apple reports
suggest a big premium
• Substantial battery mass
iPad embodied CO2 emissions
•
•
•
•
•
39%: Display module
34%: Integrated circuits
9%: External power supply
7%: Printed circuit board (excluding IC’s)
5%: Casing
• Assuming simple materials – complex alloys will be more
• 3%: Battery
• Old models for this one – could be higher
• 3%: Other (incl. transport, assembly)
• This is highly variable – other studies report more
Impact per unit mass (log scale)
Component CO2
IC die
IC packages
Circuit board
LCD module
Plastics
Metals
Mass in the product (log scale)
Impact per unit mass (log scale)
Component CO2
IC die
IC packages
Circuit board
LCD module
Plastics
Metals
“Don’t care
zone”
Mass in the product (log scale)
Embodied GHG
per component (kg CO2-eq)
Component mass (g)
Other
70
1600
1400
60
1200
50
1000
Power supply
Display
Battery
Casing
40
IC's (die)
800
30
IC's (packages)
600
Circuit boards (excl. IC's)
20
400
10
200
0
0
Netbook,
10"
iPad
iPod
touch
Kindle
Netbook,
10"
iPad
iPod
touch
Kindle
Embodied GHG (kg CO2-eq)
800.0
800.0
600.0
600.0
400.0
400.0
200.0
200.0
0.0
0.0
9/27/2012
iPod shuffle
iPod nano
iPod classic
iPod touch
iPhone 3GS
Apple TV
iPhone 4
iPad 2
MacBook
Mac mini with Lion Server
Mac mini
11-inch MacBook Air
13-inch MacBook Air
13-inch MacBook Pro
15-inch MacBook Pro
Thunderbolt Display
17-inch MacBook Pro
21.5-inch iMac
Xserve
27-inch iMac
27-inch LED Cinema Display
Mac pro
iPod touch
Kindle
iPad
Thin Client
Netbook 10-inch
Desktop - small
Switch
Laptop 16-inch
Desktop - tower
LCD monitor 21.5-inch
Laptop with dock 12-inch (ei)
LCD monitor 17-inch (ei)
Desktop (ei)
Rack server
This study (2012)
Apple product reports (2012)
Both datasets show embodied emissions roughly linear
with respect to mass (see paper for details)
Teehan & Kandlikar. LCA XII,
19
Study conclusions
• Physically smaller products = less production CO2; linear with
mass
–
–
–
–
Desktop PC (tower) = 160 kg CO2-eq
15” laptop = 108 kg CO2-eq
10” netbook = 62 kg CO2-eq
iPad (1st gen Wi-Fi) = 26 kg CO2-eq
• *** Buyer beware – best used for internal comparison only
• These numbers are lower than Apple’s; but similar trend
• Top-down EIOLCA models will produce still larger numbers.
Process-sum LCA vulnerable to truncation error. Consider
these results to be lower bounds.
Summary and research outlook
• iPad emissions comparatively small
• Production CO2-eq > Use
• More complex powerful devices will
have higher emissions
• Embodied CO2-eq roughly linear
with mass
– More stuff == more CO2
• What about emissions due to
network data transfer? They’re
quite large – see this afternoon’s
presentation
Product Carbon Footprint (kg CO2-eq)
Apple product environment reports, 2013
400
350
300
250
200
Recycling
150
Transport
100
Use
50
0
Production
Lifespan and end-of-life
• Most models assume tablets last two or three years
• Production emissions recur with each new purchase
• Extending lifespan is the most obvious way to limit
CO2 impact from tablets, if feasible
– See: other discussions on repairability
– Will the next generation be significantly more efficient,
justifying early upgrades? Unlikely – already very efficient
• Recycling has very small CO2 impact, but other
reasons to support it
Research outlook
• Carbon footprint is not a very useful number for product
differentiation due to uncertainty in methods and data
• We desperately need better data – new studies of modern
displays, batteries, casing materials; better inventories of
materials used, especially chemicals and coatings which are
difficult to identify through disassembly; this will depend on
participation from producers
• There are some emerging standards for LCA of electronics and
ICT; meaningful product comparisons will require
standardized studies which apply consistent assumptions and
models
Research outlook (2)
• Replacing PC with tablet usually a win, if practical
• Where is the leverage to reduce impacts?
– Lifespan – reduce recurring production impacts – #1
– Standardized chargers and connectors – increased part reuse
– “Less stuff”
• Other ideas, which are hard to model in quantitative LCA
–
–
–
–
Removal of hazardous substances (human health impacts)
Better recycling and take-back programs
Social justice? Worker rights?
“Higher-order” environmental impacts
Acknowledgements
Extra slides
iPod touch
Kindle
iPad
Thin Client
Netbook, 10"
Desktop - small
Switch
Laptop, 16"
Desktop - tower
LCD monitor, 21.5"
Laptop, with dock, 12" (ei)
LCD monitor, 17" (ei)
Desktop (ei)
Rack server
Embodied GHG emissions (kg CO2-eq)
400
This study (2012)
Other
Power supply
300
Casing
200
Battery
Display
100
PCB and IC's
0
iPad part mass vs embodied CO2
12
Display
kg CO2-eq
10
8
6
IC's (die)
Circuit board
Power supply
4
2
IC's (package)
0
0
Casing
Other
100
Battery
200
Part mass (g)
300
400
iPad part mass vs embodied CO2
12
Display
kg CO2-eq
10
8
6
IC's (die)
Circuit board
Power supply
4
2
IC's (package)
0
0
Increasing CO2
per unit mass
Casing
Other
100
Battery
200
Part mass (g)
300
400