A paper by data scientists Klaus Grobe and Sander Jansen explores if bitrates growth in our networks will reach breaking point, and raises the question: what is the alternative?
According to various studies on the global electric power use of the Information and Communication Technology (ICT) infrastructure, ICT’s currently significant proportion of total global electricity use is set to increase between 2020 and 2030.
The environmental footprint of the digital sector is significant, with Global Warming Potential, resource depletion, ozone depletion and various toxicity parameters among its negative impacts.
Even taking into account the linear decrease of electricity emission factors from 0.4 to 0.3 between 2020 and 2030, and the partial offset by the conversion to renewable energies, there will be a significant increase in ICT energy consumption and its Global Warming Potential beyond 2025.
Let’s take a look at the reasons why, as outlined by a detailed study "Limits to exponential Internet Growth" by data scientists Klaus Grobe, Director of Global Sustainability at ADVA, and Sander Jansen, Director Product Line Management, ADVA.
The study notes that while end-user equipment consumption has become more efficient in past years, based on the replacement of desktop PCs and cathode-ray-tube monitors by lap-tops and flat screens (especially liquid-crystal display and OLEDs), the energy consumption of data centers and core networks is increasing.
Indeed, there is a trend towards wireless video downloads in 4G and 5G networks. Currently, 50% of the energy of ICT networks is attributed to wireless networks (more than fixed access networks), and is forecasted to grow faster than fixed networks.
The main reason is that ICT parts have to cope with an accumulated and increasing number of applications. The applications that have the potential to increase bandwidth growth include: 5G, Industry 4.0, Internet of Things, HPC (high-performance computing), big data applications such as SKA (square-kilometer array), and 3D high resolution video streaming.
The increase of energy efficiency in electronic switching and fiber-optic transport is approaching some fundamental limits in the coming 10-20 years.
For both switching and photonic transport, this will be the Shannon-von Neumann-Landauer (SNL) thermal limit. Theoretically, thermodynamically reversible computing or entrophy-preserving switching can break the SNL limit, but this may not work in practice because the energy saving comes at the cost of switching speed. Certain practical limits may even be reached before the ultimate SNL quantum limit, due to the threshold of photon energy at a wavelength of 1550 nm, that of almost all commercial WDM systems.
Likewise, data center storage is also facing saturation effects, due to slowing improvements in areal density (note: areal density has an obvious impact on per-device total storage capacity) for the main media for mass storage showing. Holographic techniques or Optical Data Storage developing towards nano-photonic may become an alternative, but so far neither have seen substantial deployment.
In short, for data centers and core network equipment it has not been possible to compensate this bandwidth growth by gains in energy efficiency, unless substantial deployment of (theoretically possible but practically unproven) technologies takes place. With increasing bandwidth requirements, the saturation effects will lead to the necessity to simply use more of what is available. As a result, core-network equipment, over time, is becoming increasingly energy consuming.
"The forecasted Global Warming Potential emissions may achieve some 5% of global emissions in 2030. Based on the Keeling Curve by which de-carbonisation will be required in the coming years, the ICT sector may interfere with this requirement."
There is one important aspect that could be a way out for the emissions issue. This is the idea of "Green-by-ICT". It refers to emissions savings in sectors other than ICT than are enabled by internet and data technologies. The most relevant sectors include manufacturing, power grids, buildings, mobility, and agriculture. According to GeSI Smarter2030, ICT solutions for 21st century challenges, the carbon-saving effect on a global scale can be almost a factor of 10 times higher than ICT emissions themselves. However, this will not solve the issue of emissions by the exploding ICT sector, nor will it solve the resource depletion problems resulting from using an increased amount of ICT equipment.
What does it all mean? As the paper "Limits to Exponential Internet Growth" highlights, the risk is that the Internet either consumes rapidly increasing amounts of energy, or that its energy consumption limits the bandwidth growth and the number / kind of applications. The former can make the Internet the biggest energy and resource consuming machine on Earth, the latter has the potential for a global economic crisis.
The global ICT sector is running into a scaling problem, with the prickly question inevitably arising of how long bitrate growth in our networks can persist, and when physics will stop this growth.
Ultimately, to avoid this situation, measures need to be taken to understand for a more responsible, sustainable use of digital technologies. This will imply not only an increased use of renewable energy and of energy efficiency technology for the infrastructure, but global application of strict circular economy principles, and urgently.
Source: Limits to Exponential Internet Growth, Klaus Grobe, Sander Jansen, 2020, AVDA Optical Networking SE