January 9, 2024

What is immersion cooling and what are the benefits? Immerse yourself in the what, why and how

Writing credit: Emilia Coverdale, Marketing Project Manager at Asperitas

With Gartner predicting that 75 percent of all companies will have a datacentre sustainability strategy by 2027 [1], more and more attention is being drawn to one major energy consumer – the datacentre. Moreover, datacentre cooling. Datacentres are here to stay and they’re rapidly growing in number, but by their nature they can be seen as inflexible and energy-sapping. They face challenges on performance, efficiency and sustainability. A mere Google search shows that immersion cooling has successfully cemented itself within the zeitgeist, however, this article aims to dive deeper into what it actually is, why we need it, and how we get it.

Immersion cooling offers a solution that presents the best possible performance, energy reduction, density and flexibility for datacentre workloads. The technology itself is an IT cooling practice by which complete servers are immersed in a dielectric, electrically non-conductive fluid that has significantly higher thermal conductivity than air. Heat is removed from the system by circulating liquid in direct contact with hot components, then through water-cooled heat exchangers.

Single-phase immersion cooling using Asperitas’ natural convection method in combination with drycoolers

Power Usage Effectiveness (PUE) has been adopted as a major KPI for datacentres. The formula is simple: total energy footprint of the facility divided by the energy consumed by IT. Air cooling (the method traditionally used in datacentres) relies on fans and air circulation to dissipate heat from the IT components, while immersion cooling uses a fluid to directly cool the hardware, providing more efficient heat transfer. When the average global PUE is 1.55 [3] and immersion cooling can reduce that to below 1.1, there’s no better efficiency approach than immersion cooling in today’s market.

“Research shows that immersion cooling is the most promising technology from a performance perspective as it offers high thermal dissipation and you can recover all of the heat. It’s also clean and environmentally friendly, says Andy Young, CTO at Asperitas. Furthermore, removing the fans means that all the energy invested in the server is put to work, which adds value to the data, saving over 10% of IT power and essentially removes a failure point.”

So what else is good about it? Let’s dive in.

The benefits of keeping IT cool using immersion

Immersion cooling has many benefits, including but not limited to: sustainability, performance, reliability and cost. But when we talk about sustainability, what does that mean exactly? Simply put, lower PUE is synonymous with reduction in energy usage and CO2e emissions and there’s no water consumption due to the solution being a closed-loop system. The ability of the liquid to capture all the IT energy combined with warm water cooling enables solutions ready for heat reuse. Furthermore, there’s no need for adiabatic chillers, which is currently the main source of water consumption in datacentre operations.

On a performance level, there’s a huge density benefit. Immersion cooling allows for much higher compute density compared to traditional air-cooling methods. Since the dielectric liquid can dissipate heat more efficiently than air, tanks can be packed more closely together than racks in a smaller space, increasing the amount of compute housed in that area.

Reliability is key when adopting a new technology. On an IT level, immersing the servers reduces the risk of overheating, thermal stress and oxidation on server components by displacing air from the server components, leading to fewer hardware failures and longer equipment lifetimes. It’s also worth noting that the Asperitas natural convection system is able to function very well on high operating temperatures – high utilisation while being self- managed at the same time. But what about redundancy? Thankfully, continuous cooling and maintainability can happen concurrently, and this all happens alongside autonomous safety and comprehensive monitoring.

Cost savings come in the form of a decrease in datacentre CAPEX and OPEX. Air cooling requires large amounts of energy to continuously circulate and cool the air, not to mention run the compressors in refrigeration air chillers within the datacentre. Immersion cooling reduces energy consumption by leveraging the high heat capacity of the cooling liquid, resulting in significant energy savings. Big win.

Datacentre industry challenges wheel
Datacentre industry challenges

Commenting on immersion adoption, Maikel Bouricius, CMO at Asperitas states that:

“Sustainability and regulations surrounding the topic is at the top of the agenda when it comes to datacentre thermal management, so immersion is the logical choice, and it’s also a reliable one – reliability meaning predictable and consistent performance. Ultimately, with immersion, you’re next gen ready, and ready for the generations after that too.”

Speaking of future generations, the topic of climate change is never far away from the sustainability narrative. It’s important to think about what opportunities are available for datacentre cooling in hot climates, which can be very dry and even dusty. Dust and contaminants in the air can negatively impact air cooling systems, leading to reduced cooling efficiency and potential hardware damage. Immersion cooling eliminates these risks as the components are fully immersed in a sealed tank, protecting the IT from external contaminants.

Let’s now make a noise about immersion cooling’s lack of noise. It’s no secret that datacentres are best enjoyed with a set of earplugs, given the extensive fan operation and air circulation. Think about it this way – the noise you hear is wasted energy you’re paying for. Immersion cooling significantly reduces noise levels as no fans are required for cooling, resulting in quieter working conditions within the datacentre. This creates a convenient environment for things like service and maintenance – which doesn’t need to be as messy as one might think...

Spilling the tea on the reality of working with fluids

An understandable misconception of immersion cooling is that it makes a splash. Right on your datacentre floor. Thankfully, that doesn’t need to be the case. With the right training, PPE and service tools, the reality of working with immersed IT can be quite straight forward. Previously, datacentre operators may have seen immersion as being a tricky choice due to these concerns about maintenance, but with offerings that include expert commissioning and servicing as well as innovative add-on solutions such as service trolleys, maintaining an immersion system is simple and efficient..

Asperitas’ AIC24 21” solution with service trolley, used for server insertion and maintenance

How can it be done with confidence?

It all starts with planning and road mapping. Setting sustainability objectives is one thing, but it’s important to also identify your performance requirements for the next few years. Lastly, where do you see your workloads being facilitated?

The next step is sharing your project brief. Then it's a matter of gaining experience via remote testing and on-site experiences, starting with piloting and then building your scale-out plan.

“Realistically, a hybrid form of cooling for datacentres is the likely scenario moving forward, says Bouricius. At the moment, we’re seeing a variety of usecases – standalone, integrated, owned and colocation. Immersion can be applied in all of these options while keeping in line with regulations such as the European Energy Efficiency Directive. In the long term, we see greenfield datacentres as the way to go to fully see the impact on sustainability.”

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