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How optical fibre will help create a sustainable future for data centres

How optical fibre will help create a sustainable future for data centres

Green TechnologyIndustry ExpertNetwork & Storage

Virtual connection, technological advancement and desires for machines to function faster have inevitably led to data centres becoming more resource hungry. Industry experts at Corning Incorporated – Aislin Sullivan, Program Director, Sustainability; Dr Pushkar Tandon, Corporate Fellow; and Dr Roshene McCool, Senior Market and Technology Development Manager – and Sphera Solutions – Amalia Diaz and Dr Ing. Constantin Herrmann – assess data from Corning’s LCA study and explore how optical fibre can reduce carbon footprint and prepare sustainable operations for decades to come.

Optical fibre is at the heart of our modern connected world, transmitting massive amounts of data daily. Today’s connections are made possible by beams of light propagating through hair-thin strands of optical fibre, each potentially capable of supporting more than 150 terabits of data per second.

With the current data rate explosion in data centre applications, managing energy consumption and developing sustainable solutions are becoming paramount considerations in optical fibre network expansions, a trend that is likely to accelerate.

Fibre is integral to some of the technological advances that are driving the future. AI and Machine Learning techniques – the engine of data driven decision making – use fibre optic meshed networks to connect massive amounts of data to processing machines at high speeds. The rise of remote working, video conferencing and the ability to connect to any customer, colleague or family member anywhere in the world, while on the move, is enabled by a worldwide network of fibre optic cables.

In addition to enabling massive bandwidth, optical fibre networks offer environmental benefits over traditional telecommunications networks that use copper. Low energy consumption, low maintenance and future readiness are among the most evident advantages and have been quantified extensively. Less often talked about is the embodied carbon of optical fibre. 

Embodied carbon

The embodied carbon associated with raw material extraction, manufacturing, transportation and End-of-Life of network infrastructure is a critical element when comparing the environmental impact of competing digital technologies.

Corning executed an LCA of the materials contained in optical fibre and its manufacturing process to assess its environmental impact, quantified as carbon footprint (CF). The results from this study were compared to the CF of copper based on publicly available data.

It calculated the carbon footprint of one optical fibre to be 2.3 kg CO2eq/km, while two 0.5 mm copper wires (used in Asynchronous Digital Subscriber Line) are estimated to have a carbon footprint of 14 kg CO2eq/km – 6x the carbon footprint of fibre over the same length. The latest fibre networks for home users, however, can deliver 2,000 times higher bandwidth over 7x longer distances for the same number of users.

Based on these values, it is estimated that to achieve the same transmission capacity, over the same reach, the twisted copper pair has a carbon footprint up to 85,000x higher than that of an optical fibre.

While this analysis is non-exhaustive and excludes recycling and disposal, as well as other materials and equipment needed to make both cables and operate both networks, it conservatively elevates optical fibre networks over copper from an embodied carbon perspective. This complements the findings of other studies that have confirmed that environmental and economic benefits can be achieved with optical fibre by eliminating active components and simplifying network architecture. Ultimately, studying the embodied carbon that results from the materials and manufacturing of optical fibre helps further improve its environmental performance.

Corning’s Cradle-to-Gate LCA study

An LCA is a standard methodology used to quantify the potential environmental impacts of a product or process. It is performed by calculating the GHG emissions associated with the entire life cycle of the product. A commonly used metric that results from an LCA is the global warming potential (GWP), also known as CF. To estimate the CF of optical fibre, all substances needed upstream for its production are considered, as well as electricity and other utilities in what is called a Cradle-to-Gate analysis. This considers all the resources needed and emissions caused by raw material extraction (‘cradle’), their processing into semi-finished products and final manufacturing into optical fibre that is ready for further distribution (‘gate’).

Corning collected primary data from its production sites and detailed material information to quantify the Cradle-to-Gate impact of its optical fibre and optical fibre cables. Using the calculation method Environmental Footprint 3.0 (EF3.0) and according to the principles and requirements of ISO 14040 and 14044 standards, Corning’s LCA study confirmed that the electricity required to manufacture optical fibre is the main source of impact, contributing 70-80% to the overall CF. The study also estimates the raw material impact to be 15-20% of the overall CF.

A Cradle-to-Grave analysis was also carried out to understand the impacts of the entire life cycle. This analysis expands the boundaries to consider distribution and End-of-Life, where recyclability and other concepts of circularity play a key role. The Cradle-to-Grave analysis also confirmed that electricity and raw materials in the manufacturing stage are the main hotspots.

Raw material impact

Corning requires highly pure raw materials to produce low attenuation (low loss) optical fibres. These include silica or doped silica glass, protective acrylate coatings and other auxiliaries. 

Results from Corning’s LCA study indicate that raw materials contribute between 15% to 20% of the total CF of optical fibre, with 50% of this impact attributed to the silica glass precursor used in the chemical vapor deposition process and 40% attributed to the acrylate coating.

In general, for an optical fibre with smaller coating diameter, less coating material is needed, resulting in a lower CF of the fibre. In fact, the LCA confirmed that the raw material CF of a 125 μm glass diameter and 190 μm in coating diameter fibre is 17% less than the raw material CF of the standard 242 μm coating diameter fibre with similar glass diameter. This represents a 3% reduction in overall CF between the two fibre types. As industry trends continue to drive towards increased density, reduced coating diameter fibres result in a favourable impact in both fibre and cable CF.

Manufacturing impact and contribution of electricity

Upstream impact of materials is an important part of Cradle-to-Gate studies, but it does not consider the whole picture. The utilities required to convert those materials into the final product, optical fibre, were also included in the LCA. Fibre production is an electricity-intensive process. Process water, thermal energy and waste have a negligible impact compared to the electricity requirements for manufacturing optical fibre and to the raw materials previously discussed.

Corning’s LCA study uses data from relevant factories, which use electricity from the standard grid mix. Since electricity impacts 70-80% of the total optical fibre CF, the value of continued energy efficiency efforts and a greener electricity mix is clear. The impact of renewable electricity was studied and the LCA confirms that CF can decrease by up to 70%, leading to a 0.70 kg CO 2eq/km value, further improving the current CF advantage over copper-based networks by a factor of 3. High-performance fibres with reduced coating diameters like Corning’s SMF- 28 Contour optical fibre portfolio enable increased cable and duct density while reducing size and materials in cables and solutions. This poses yet another opportunity for further improvements in optical fibre CF. As the impact of raw material is reduced, the fraction of contribution from electricity increases, with conversion to renewable electricity providing an opportunity to significantly reduce cable’s CF.

The future is fibre

The world depends on data more than ever and optical fibre has demonstrated superior capabilities over all other alternatives, offering massive capacity that expands the bandwidth of human potential while reducing power consumption and embodied carbon.

The industry must scale in a sustainable way and optical fibre offers the best pathway from an economic, environmental and social aspect. Compared to copper-based networks, optical fibre reduces energy consumption by up to 54%, reduces operational costs due to lower maintenance requirements and offers high-performance and high reliability that lasts a lifetime. Optical fibre also provides an opportunity to reduce embodied carbon by at least 85,000x when considering the materials and processes needed to achieve the same transmission capacity over the same reach in a copper network. This improvement potentially increases by a factor of three when 100% implementation of renewable electricity in optical fibre manufacturing is achieved.

Looking a decade ahead, the IT industry has a tremendous opportunity to move the world forward – by connecting the unconnected and building out the cloud to serve the data demands of tomorrow. Making sustainable choices, quantified by industry-recognised and transparent studies, is our responsibility.

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