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Wed 5 Jun 2024

In this feature, Astrid Wynne, Head of Public Sector and Sustainability at Techbuyer, and Chair of the DCA Sustainability Special Interest Group, discusses the impact of the US-China tech trade war on Gallium prices and semiconductor manufacturing, the increased focus on data centres’ resource usage due to artificial intelligence (AI), and severe global water stress.

In April, the mainstream press reported the escalating technology trade war between the US and China is resulting in a doubling of Gallium prices, with a high impact on the manufacture of semiconductors. Meanwhile, plans advance for governmental ratification of deep-sea mining for metals used in battery production. We are running short of resource, and these are some of the results.

This, and the attention generated by AI is bringing increased focus on data centres. Researchers at the University of California, recently found ChatGPT uses half a litre of water for 10-50 prompts. The prospect of having this on our mobile phones, raised questions on how we are going to manage this scale of water and electricity use. The sector is increasingly looking at metrics on each and the interplay between them.

The headline water usage issue

According to the Stockholm Resilience Centre, we have exceeded the safe limits of “green water” (above ground) and “blue water” (subterranean reserves) are in a much worse position. The World Resources Institute stated around 25% of the world’s population live under extremely high water stress year round. By 2050, an additional 1 billion people are expected to live with extremely high water stress, and the number rises if we exceed a 2.4 degree temperature rise.

Estimates vary even on the direct water footprint of DC operations. An average figure for a 1 Megawatt enterprise data centre is 25 million litres per year (about the size of 10 Olympic sized swimming pools). Google and other hyperscale data centres estimate 760 million litres per year in their operations. This figure will be dwarfed when the water footprint of the data networks, energy supply and equipment is taken into account.

Water usage of DCs

The standard efficiency metric for water efficiency is Water Usage Effectiveness (WUE). This is calculated by dividing the annual site water usage by the IT equipment energy usage in kilowatt hours. However, with the work on energy consumption of electricity usage advancing, the calculation may become more complicated. This is because there is a water footprint in the energy itself, and it is variable.

Hydrocarbon power plants and hydropower plants have considerably higher water consumption solar and wind power. This means location of energy production will have an impact on its water footprint. This can be calculated on national averages (e.g. 1.33 m3 of water per MWh in the UK, 4.23 m3 in France, 2.04m3 in Germany and 1.31m3 in the Netherlands), or it can be calculated in down the wire energy.

In the past, data centre builds have been in areas that have good power availability or in areas where a strong energy supply can be created by renewable means. However, with water stress is increasingly on the agenda, decision making needs to adapt. A study by American academics found less than a fifth of the DC energy demand was from sites in the West and Southwest US. However, these used almost a third of the indirect water footprint of the sector. This was unexplored when the paper was published in 2021. It is unlikely to be unexplored for long.

And then there is the supply chain…

Data centres do not exist if they do not have servers to house. This IT load comes at significant embodied water cost. According to Morgan Stanley, making semiconductors is among the most water-intensive undertakings out there, using about 1,869 m3 per dollar of spend. Up to 30 litres of water were needed to make a single chip back in 2016 according to Earth Magazine. Growing complexity in the manufacturing process is likely to have increased this over the past 8 years, so we can expect the number to be higher now. An entire circuit board requires 4,165 litres of water to create according to an Innov Energy blog.

Alongside this, there is the water required for the networking infrastructure and cabling. The production of copper is a very water intensive process – roughly 455 cubic meters are required for each tonne. With the miles of cabling within and from the data centre, this represents a significant water spend.

So, what can we do?

The data centre sector has been aware of water efficiency within the building for a long time. Interventions like alternating cooling strategy, novel evaporative condensers , installation of redundant multi-chillers , introduction of hybrid (water–air) cooling systems  have all helped to increase water efficiency as measured by the WUE metric. There are also some novel approaches like sea water for cooling that avoid freshwater use.

Alongside this, it is a good idea to factor in the water footprint of the energy used. This can be used to choose the type of renewable supply, for example, and also as a balance to water savings on the cooling equipment.

Extending product life for servers, storage and networking will reduce supply chain water usage in the production of new equipment. Selling to the secondary market will allow the same savings for other organisations in the digital sector.

Alongside this, there is a lot of work being done by the hyperscale data centres on returning water for community use and water restoration projects. Some of this fits into the combined heat at power approach that is growing in popularity. In cooler areas, “waste heat” can be used for local swimming pools and houses. In hotter climates, it can be used for desalination plants, thereby increasing freshwater levels.

This all starts by measuring the problem and designing systems to address it, so let’s do that.

Astrid Wynne is Head of Public Sector and Sustainability at Techbuyer, a sustainable IT solutions provider. She has represented the company on a number of Circular Economy research projects in the data centre sector. Astrid is also chair of the Sustainability Special Interest Group at the Data Centre Alliance.

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