From the CTO’s corner: Simon Gardner, Oper8 Global Group

Excuse the pun, but technology developments to manage the thermal demands of data centres are hot right now.

I recently wrote about direct-to-chip (D2C) liquid cooling, but the other big emerging field is immersion cooling. That’s where you mount your servers vertically and immerse them completely into a bath of dielectric fluid. And, just like D2C liquid cooling, you can have both single-phase and two-phase immersion cooling. While I explored the differences between the two methods in my D2C post, given immersion technology is still quite nascent I’ll just tackle the subject as a whole.

Interest in immersion cooling is high for a number of reasons.

Most prominently, it is being driven by the rapid growth in demand for edge computing – where the low latency requirements of AI, ML or IoT applications necessitate processing close to the source. However, these locations could have any number of constraints that make it difficult to deploy data centre infrastructure – power or water availability, space, or hostile environments like manufacturing facilities or mine sites.

Immersion cooling offers a lot of advantages to overcome these edge computing constraints.

These edge AI, ML or IoT applications typically require higher performance and higher density computing, which in turn leads to higher cooling requirements. With lower power requirements and far greater cooling efficiency than traditional methods, immersion cooling has the potential to reduce the overall data centre energy demand by more than 10%. That either allows you to channel more electricity into your computing resources or it makes it more feasible for you to locate your data centre in places where power is more expensive or supply is limited.

It’s a similar story with water. A lifecycle assessment study published in Nature found that blue water consumption was reduced by 31-52% in data centres using advanced cooling methods, such as cold plates and immersion cooling. Reducing both energy and water use is a key step towards net zero data centres.

Enabling higher density computing, as well as doing away with peripheral coolers, chillers, fans and evaporative cooling systems, immersion cooling reduces the amount of floor space you need, which gives you the option either to use more expensive floor space or spend more on other components, given floor space can be a significant proportion of the budget when you are evaluating the economics of a new build. Shell, for one, estimates that immersion cooling can help businesses cut the floor space needed to host their computing equipment by up to 80%.

Immersion cooling is also a perfect way to address the spatial, power and thermal constraints of certain hostile environments. We often see these onboard ships, at remote mine sites or in noisy and dusty manufacturing facilities. I know of one high-performance computing unit being used onboard for subsea mapping for oil rig exploration. In dusty conditions or environments with high particulate matter, immersion cooling provides better environmental isolation, while any form of air cooling will tend to increase the circulation of that dust in your data centre.

With any emerging technology there are also some words of caution.

If you have an existing facility and you want to retrofit it with immersion cooling, you will need to replumb. Given traditional air cooled data centre designs generally do whatever they can to keep liquids out of the data halls, this replumbing could be very extensive and expensive.

Also, we aren’t just dealing with water here, so any plumbing needs to be more than robust. Most dielectric fluids (generally vegetable oils or fluorocarbons) will need special handling, and any leak isn’t just catastrophic for your data centre equipment and its operation, there is also the potential for wider environmental damage plus the costs of any regulatory penalties and the cleanup.

On the issue of cost, the final challenge to designing a data centre using immersion cooling is that the system you deploy may require non-standard equipment and rack configurations to fit into the immersion tanks.

So where do we stand? There are a lot of emerging use cases where immersion liquid cooling can play a key role, and now is the perfect time to start investigating how you can apply it in your own facilities. I’d love to have a chat.