Growth and sustainability aspects of WDM

Growth and sustainability aspects of WDM
OFC2022, special session: Network evolution and adaptation to environmental change, San Diego, March 9th, 2022
Dr. Klaus Grobe, ADVA
Anyone who believes exponential growth can go on
forever in a finite world is either a madman or an economist.
Kenneth E. Boulding, 1910-1993, English-born American economist, educator,
interdisciplinary philosopher, and inventor of the Circular Economy concept

© 2021 ADVA. All rights reserved. Confidential.
2 © 2022 ADVA. All rights reserved.
CONTENT
Growth, growth, growth, ...
1.
Impact and way out
2.
Impact in more detail
3.
Conclusions
4.

The author wants to thank Prof. Jørgen Randers, one of
the authors of the 1972 MIT report Limits to Growth, for
his encouraging feedback on the abstract of this paper.
Growth, growth, growth, ...

Internet throughput forecast
• According to Cisco VNI 2018-2022, the
Internet throughput has a CAGR ≈ 26%
• No apparent sign that this will stop –
5G, 6G, Industry 4.0, IoT (M2M), Big Data, …
• This has impact in particular on infrastructure ICT
equipment, e.g., DWDM energy consumption
[Cisco White Paper, “The Zettabyte Era: Trends and Analysis,” June 2016], [Cisco White Paper, “The Zettabyte Era: Trends and Analysis,” June 2017],
[Thomas Barnett, Jr., et al., “Cisco Visual Networking Index (VNI) Complete Forecast Update, 2017–2022,” Cisco Knowledge Network Presentation, Dec. 2018]
1E-2
1E-1
1E+0
1E+1
1E+2
1E+3
1997 2002 2007 2012 2017 2022
Throughput
WDM System Capacity [Tb/s]
ICT global Throughput [TB/s]

[Hintemann et al., Electronic Goes Green 2016+, Berlin, September 2016]
ICT power consumption (here: Germany)
• Energy consumption of internet
infrastructure – networks and data-
centers – grows exponentially
• Decrease for end-user equipment.
This is mainly due to improvements
in flat screens and laptops.
Power consumption of ICT infrastructure segments predicted to grow exponentially
2010 2015 2020 2025
40
30
20
10
0
Energy
Consumption
[GWh/Year]
Smartphones, Tablets
Computers
Networks
Data Centers
50
8% p.a.
6% p.a.

Equipment power consumption
[H. Mellah, B. Sansò, June 2011, DOI: 10.1109/WoWMoM.2011.5986484], [Vereecken et al., IEEE COMMAG, Vol. 49, No. 6, 2011],
[Tucker et al., ECOC 2008, based on METI, 2006, Nordman, 2007], [ADVA research and specifications]
• Router, switch and WDM
power consumption is
exponentially increasing
• Energy efficiency gets better,
but obviously cannot cope
with bitrate increase
1E+0
1E+1
1E+2
1E+3
1E+4
1E+5
1E-1 1E+0 1E+1 1E+2 1E+3 1E+4 1E+5
Power
Consumption
[W]
Throughput [Gbps]
Switches Router WDM Transponder WDM Plugs
Per Equipment Class, almost linear in Time

Latest WDM achieves efficiency rating (TEER) of ~0.2 W/Gbps
WDM power-efficiency development
Strong improvement of WDM energy efficiency – but absolute consumption still increasing
[ICT Ecology Guideline Council, Ecology Guideline For the ICT Industry, 2021
https://www.tca.or.jp/information/pdf/ecoguideline/guideline_eng_9.pdf ]
Together with the improving emission factors – higher degree of
renewable energy over time – the energy-efficiency improvement
keeps our photonic-products use-phase emissions stable
0.01
0.1
1
10
1 10 100 1000
WDM
Efficiency
[W/Gbps]
WDM Channel Bitrate [Gbps]
Transponder
WDM Plugs
1996
2020
2001 2006
2017
2009
0 50 100 150 200 250 300 350
2017
2018
2019
2020
2021
Global Warming Potential [ktCO2e]
Products Use-phase Products Components Transport All ADVA Activities

Switching and transport energy limits
1E-21
1E-20
1E-19
1E-18
1E-17
1E-16
1E-15
2000 2010 2020 2030 2040
E
Gate
[J]
CMOS Node Number
(Feature Size in nm)
65
22
ln2 kBT SNL Thermal Limit
45
Photon Energy hν @ 1.55 µm
90
32
130
18
7
[R. Tucker, Switching and Energy, based on ITRS ’97-’09 Roadmaps]
• Per-bit switching and
transmission energy is
approaching the SNL
fundamental limit
• Optical transmission will
reach limits even earlier
• Even bio-cell processors,
Nano tubes etc. cannot
avoid the SNL limit –
they just get closer…

Impact and way out

Internet energy consumption prediction
GWP : Global Warming Potential in [kgCO2 equivalents]
• For the GWP, future electricity emission
factors have been extrapolated
• Is the Internet becoming the ultimate
energy-consuming machine…?
• … or will Internet bitrate-increase
(overshoot and) collapse…??
0
1000
2000
3000
4000
5000
2010 2015 2020 2025 2030
GWP [MtCO2e/a]
Energy Con. [TWh/a]
Throughput [TBps]
[A.S.G. Andrae, Int. J. Science and Engineering Investigations Vol. 8, Issue 86, March 2019], [Cisco VNI, extrapolated beyond 2022],
[GWP calculated w/ emission factors known till 2018 and predicted till 2030]

The consequence…?
10
20
30
40
0
2030
2020
2010
2000
1970
1960
1950
1940
Global
total
CO
2
Emissions
[GtCO
2
/a]
1990
1980
Start
of required
Decarbonization
Heavily increasing Internet Emissions
CO
2
Concentration
(Keeling’s
Curve)
[ppm]
320
360
400
280
440
[Scripps Institution of Oceanology, Keeling Curve, online: scripps.ucsd.edu/programs/keelingcurve/wp-content/plugins/sio-luemoon/graphs/mlo_full_record.pdf]
[H. Ritchie, M. Roser, "CO₂ and Greenhouse Gas Emissions," 2020, Retrieved from: ourworldindata.org/co2-and-other-greenhouse-gas-emissions]

The consequence: kill flat-rate…!
Use of the Internet must be properly charged, according to the environmental damage.
This may necessitate unpopular actions like:
• People get charged for internet use on an environmental-cost basis
• Companies like social-media providers get charged, e.g., per bandwidth
• High-resolution content is subject to cost penalties
… or Internet bitrate-increase may (overshoot and) collapse…

Quantums (well, photons) of solace…
Global ICT-enabled CO2 Reduction 2030
Sector GtCO2e
Manufacturing 2.7
Energy 1.8
Buildings 2.0
Mobility 3.6
Agriculture 2.0
Total global 12.1
Global ICT Emissions 2030 1.25
Saving Factor 9.7
[#Smarter2030, Executive Summary, GeSI, 2015]
• ICT can over-compensate its damages
• GWP savings elsewhere can be higher by ×10
• Does not solve the scaling problem…
10
20
30
40
2030
2020
2010
2000
Global
CO
2
Emissions
[GtCO
2
/a]
1990
1980
ICT Emissions
Greening-by-ICT
Carbon Savings
1970

Impact in more detail

Lifecycle assessment (LCA) for 400G/600G WDM transceiver
• Use phase – energy consumption! – dominates WDM environmental impact
• Results confirmed for routers / switches, e.g., by Cisco
Assumptions
• 8 years lifetime (use phase)
• 24/7 always-on use mode
(negligible downtime)
• Globally averaged grid-mix
emission factors as of 2019
(~0.41 kgCO2e/kWh)
0% 20% 40% 60% 80% 100%
Global warming potential
Eutrophication potential
Terrestrial ecotoxicity potential
Acidification potential
Marine aquatic ecotoxicity
Abiotic resource depletion
Human toxicity potential
Freshwater aquatic ecotoxicity
Photochemical oxidation
Ozone layer depletion potential
Support Production Distribution Use EoL

LCA: lifetime limitation for hi-capacity WDM
• How long should an old WDM system’s life be extended – until this is GWP net-negative?
• New – replacement – system has better energy efficiency, however, its production etc. cost CO2
For the fiber-monitoring system analyzed here,
replacement for reasons of energy efficiency
does not make any sense
GWP : Global Warming Potential
0.0
0.2
0.4
0.6
0.8
2020 2030 2040 2050
Lifetime
GWP
[tCO
2
e]
ALM64 (OTDR)
No Replacement
With Replacement
0
10
20
30
40
50
60
2020 2030 2040 2050
Lifetime
GWP
[tCO
2
e]
400G/600G DWDM
No Replacement
Replacement after 8 Years
Optimum Replacement

Conclusions

Conclusions
• Bit rates and energy consumption of core-network ICT equipment are exponentially growing
• Emissions likely to stay stable or slowly decline over time (improving emission factors)
• Certain equipment should be replaced after several years for reason of energy efficiency
(holds for the next two decades or so)
• Saturation effects will pose challenges on energy-efficiency improvements
• ICT emissions can be over-compensated in other sectors

Thank you
IMPORTANT NOTICE
The information in this presentation may not be accurate, complete or up to date, and is provided without warranties or representations of any kind, either express or implied. ADVA shall not be responsible for and disclaims any liability for
any loss or damages, including without limitation, direct, indirect, incidental, consequential and special damages, alleged to have been caused by or in connection with using and/or relying on the information contained in this presentation.
Copyright © for the entire content of this presentation: ADVA.
info@adva.com

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