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Liquid Cooling Sustainability Gains – Energy Efficiency and Data Centre Waste Heat Recovery

Liquid Cooling Sustainability Gains – Energy Efficiency and Data Centre Waste Heat Recovery

By David Craig, CEO of Iceotope

With environmental, social and governance (ESG) objectives at the forefront of many organisations business goals for 2021, it’s clear we are in the midst of a transition to a low-carbon economy. While as a society we recognise the urgency of the climate crisis, both the ecology and the economy of the situation are beginning to take hold. Businesses are expanding the traditional definition of shareholder ROI to not only incorporate sustainability goals but to use sustainability as a means to improve their bottom line. 

For example, this year in Europe, 88% of companies are planning to increase investments into digital processes and sustainability practices compared to 58% in 2020. In the data centre industry, specifically, a recent Schneider Electric survey with the 451 Group interviewed more than 800 global data centre operators and found that 97% of providers’ customers are asking for contractual sustainability commitments. Sustainability is no longer “nice to have”, but a “must-have” business requirement. 

The worldwide data centre industry has managed to hold steady at 1% of global energy demand in spite of internet traffic increasing 12-fold since 2010. Much of this has come from the shift to cloud and hyperscale environments, but more will need to be done as data centre demand continues to grow. The challenge now becomes where to find additional sustainability gains. 

Liquid cooling offers data centre operators the opportunity to reduce infrastructure energy use, improve PUE, capture and reuse waste heat, and meet sector targets to be net-zero carbon by 2030. A recent Cundall report assessed the performance and energy efficiency of liquid cooling approaches and found that with liquid cooling, carbon emissions could be reduced by around 11% per kW of ITE power, per year. This is against best-in-class air cooling in hyperscale, it follows that the vast majority of the world would see 2x, 3x and in some cases even 4x savings above that level. For a typical 150MW hyperscale data centre consuming approximately $200 million worth of electricity per year, that is $22 million in savings. 

The first place most people look to is power and water efficiencies. Cooling power can be more than 35% of a data centre’s total energy consumption and in 2020, US data centres alone consumed an estimated 174 billion gallons of water. It makes sense to address those two key areas first. However, several other areas tend to get overlooked but are equally as important and impactful to overall sustainability. Let’s explore density, supply chain and heat recapture/reuse in more depth. 


Contrary to accepted data centre colocation best practices, the industry is likely to see a trend towards smaller data centre footprints moving forward. This is being driven by a few factors all of which have an impact on sustainability. First are the costs of new construction. New building construction impacts the environment through land opportunity cost, natural resources used, materials for building, as well as waste production and disposal. There is a carbon footprint for every extra square foot of a building that wasn’t there before. 

In addition, certain countries and municipalities are facing growing pressure to refuse new data centre builds. Be it for political or environmental concerns, the move to repurpose brownfield buildings begins to make more sense in a post-pandemic era. Repurposing office blocks no longer being used to the same capacity is a very smart alternative. Construction costs are reduced and the time to launch the data centre site is faster. Both have a strong economic benefit in addition to the environmental one. 

Finally, the move to edge computing is changing the way we process data. A quote from Gartner is that ‘the data centre is no longer the centre of the data’. We see that occurring with new and emerging workloads happening in any location. Compute is being processed closer to the user than ever before. This will continue the drive for smaller footprint solutions that maintain the same level of data centre density without sacrificing energy efficiency.

Supply Chain

Accountability for the supply chain is becoming an imperative sustainability metric. Last year Microsoft announced a net negative carbon strategy that included plans to see their suppliers reduce their scope 1, 2, and 3 emissions, a first for the industry. For the entire industry, the ability to remove volume, materials, and movement is only going to gain prominence. 

Immersion liquid cooling has a role to play in that process. With a sealed chassis, all the server components are cooled using precision delivery of dielectric coolant. Dielectric coolant in and of itself is a byproduct of the carbon process. When well maintained, it does not break down easily, which enables it to be recycled for several life cycles and can outlive the ITE it is cooling. 

Liquid cooling also reduces the overall data centre space for a given IT load by eliminating the need for hot and cold aisles. The physical space of the server is scaled back, and as a result, so too is the number of components in a data centre operator’s supply chain. Thousands fewer chips, motherboards, power supplies – and all the individual electronic pieces that make up that equipment – can be eliminated when the server footprint is reduced. 

The push towards supply chain sustainability also coincides with the fact that high-performance computing, and its higher density CPUs and GPUs continue to strain traditional air cooling methods. A recent ASHRAE report highlights a 20% increase in the power requirements of servers from HPC workloads. Air-based data centre cooling systems are being pushed beyond the limits of their capabilities and effectiveness. As well as powering the HPC ITE, the increasing energy required to air-cool HPC IT environments is becoming unsustainable and costly for a data centre operator. 

Heat Recapture and Reuse

Amongst the stories making headlines are towns and villages where homes are heated by data centre heat waste, and liquid cooling provides unique capabilities to make this happen. Typically, a data centre environment is cooled using chillers to blow air through hot and cold aisles, not the most effective solution for heat recapture. Immersion cooling technologies use liquid to cool the servers. They are able to do so at a higher temperature, around 50°C, and are a thousand times more effective at retaining and transferring the heat. The heat then becomes an almost immediately useful byproduct by being at the right temperature, in the right format and easily transportable. 

Challenges remain in implementing heat reuse. Data centres tend to be located outside of towns and cities and not where homes are located. Storage technologies still need to be improved so any surplus gains achieved during the summer, for example, can be effectively stored and used during the winter to heat homes. Finally, the process of converting heat waste to electricity itself still needs to be refined. 

However, heat recovery and reuse is a massive imperative given the net-zero initiatives being established throughout Europe and around the world. As part of the UK’s initiative, we will see the elimination of gas boilers to heat homes, increasing the urgency for alternative solutions. This also brings an economic opportunity to drive growth with sustainable energy. The local data centre can create data, jobs, and revenue for a community. If it can also convert heat energy for use in homes, then there is an opportunity to create a sustainable circular economy that gets us to net-zero carbon even faster. 

Implementing and capitalising on the sustainability gains outlined here requires leadership and vision. The data centre industry was built upon an engineering mindset, which has been necessary and taken us far. To carry us forward, we need to be aware of the increasing impact of data. A moral argument can, and should, be made to use technology to stimulate economic growth while causing the least amount of harm to the planet. This shift to a low carbon economy requires new ideas and solutions to address the problems and leaves no excuse for non-sustainable technology. The time has come for us all to determine how to play our part in making this happen.

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