It is a Sunday afternoon, you are scrolling through Instagram while the Netflix show you’ve watched at least three times is playing distractingly in the background. You are not really paying attention to the feed. Instead, you are thinking of uploading photos from the weekend onto Facebook before a notification from the smart watch on your wrist interrupts. While you’ve been enjoying the perks of the digital age, there are billions of gigabytes of data flowing from your devices to the ‘sky’. However, this data does not just disappear into the “cloud”, but ends up in vast, windowless buildings filled with rows and rows of ‘Orwellian’ servers.

Millions of data centres around the world run our planet’s digital services and support the increased use of cloud-based technology. They account for 3% of total energy consumption and 0.3% of overall carbon emissions, while the information and communication technology (ICT) sector as a whole contributes around 2% to global emissions. Although this seems insignificant, because the global data traffic is growing exponentially, it is predicted that data centres will consume 10% of overall energy by 2030. That is a fivefold leap in just ten years. According to New Scientist, one of the most significant contributors to the increased energy consumption is video streaming from sources like Netflix, Amazon Prime Video, Hulu and others, which account for a daunting 60% of global internet traffic.

Although big tech companies like Facebook, Apple, Google and the like have made a long-term commitment to be 100% renewable powered, the availability of renewable energy sources to power data centres is still a problem in the ICT sector. The carbon footprint is especially problematic for those built in Asia, which is experiencing the fastest growth in data traffic. Centres for internet giants such as Alibaba, Naver, Tulip Telecom among others remain heavily dependent on coal power. For instance, Data Centre Knowledge estimates that in 2018, 73% of electricity consumed by China’s data centres was generated from coal. As consistently reported by the United Nations' Intergovernmental Panel on Climate Change (IPCC), coal power is the single greatest cause of greenhouse gas emissions.

"...raising public awareness about the impact of data centres on our climate by exposing the black box of the ‘cloud’ in the public imagination is crucial."

Steps have and are being taken to reduce this footprint. The industry standard for measuring energy efficiency of data centres is Power Usage Effectiveness (PUE) - the ratio of the total amount of energy used in

the centre to the amount needed to run the processors themselves. A decade ago, the average PUE of data centres was 2.5, meaning that it took 2.5 times more energy to cool the centres than to run the

processors. Advances in technology and design improvements have been able to limit the energy consumption of data centres despite the rapid increase in global data traffic over the last decade. Some reports even show facilities reaching a PUE as low as 1.12.

One of the main reasons why data centres have become more effective over the last decade is the “hyperscale shift” – the move towards extremely efficient data centres. Started by Facebook in 2011, this trend uses the computer architecture’s ability to scale hundreds of thousands of servers. “Hyperscale” refers to both the size of the facility and the ability to optimize its operations, and because of their straightforward design, centres are more easily able to add servers and power as they expand. These types of data centres allocate electrical power and balance workload across multiple servers as well as maximize cooling efficiency by concentrating cooling in servers hosting higher workloads.

Almost as important as switching data centres to low-carbon energy sources is improving their energy efficiency. The largest operation expense in data centres is powering the climate control system. Therefore, developing more advanced cooling techniques would drastically improve the PUE, and this is where solutions become very interesting.

"...73% of electricity consumed

by China’s data centres was generated from coal."

One is to locate data centres in cold and windy climates that provide natural cooling for the servers. A fast-emerging data hub, Iceland is home to several large data centres providing clients with a wide range of data services; from Bitcoin mining to BMW crash simulations. Icelandic data centres like Advania and Verne Global take advantage of the cool climate and use it for climate control in the centres. The carbon footprint is further reduced as a result of available renewable energy sources, including geothermal (see Fig. 1) and hydroelectric power. Moreover, the heat from the processors can be utilised to divert the hot air to a nearby city’s heating system, adapting a wasteful problem to serve as another sustainable solution.

Figure 1

While locating data centres in near-freezing climates is relatively easy to achieve, the overheating problem can be approached more creatively. A radical example of this is Microsoft’s project “Natick”, which is exploring the idea that data centres can be based on the sea floor. In the summer of 2018, a shipping-container-sized data centre prototype was lowered into the seas off the Orkney Islands. The data centre can operate for up to five years without maintenance, is powered by tidal turbines and wave energy converters, and is naturally cooled by the sea water. Given that about half of the world’s population lives within 200 km of a coastline, having these centres near large cities would provide smoother and much more efficient data traffic.

Steps are being taken to reduce the carbon footprint associated with the expanding energy consumption of data centres. However, it will take more than incremental efficiency improvements or delightfully imaginative data centre positioning to tackle what will become an exponentially more serious problem in the future. Educating both consumers and companies within the ICT sector would be a significant step towards environmentally conscious data usage. As heavyweight tech companies are exposed to criticism for contributing to climate change, there should be mounting pressure on them to reduce the carbon footprint of their data centres. As some are beginning to argue, raising public awareness about the impact of data centres on our climate by exposing the black box of the ‘cloud’ in the public imagination is crucial. Highlighting how your Netflix show, Instagram story and Facebook uploads represent much more than clean data exchange is a big part of this vital reconfiguration process.

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