Immersion Datacenter Cooling: Sustainability and ESG

In my previous article, I discussed the flexibility of immersion cooled infrastructure, particularly for edge deployments, as well as its potential to enable significant scalability for datacenter operators while improving their environmental, social, and governance (ESG) posture. Now, let's delve deeper into the environmental sustainability benefits of immersion cooling, focusing on its impact on Power Usage Effectiveness (PUE), Water Usage Effectiveness (WUE), and heat reuse.

I came across a great info-graphic by Shell, yes Shell, that, in hindsight, I could have replaced all my articles with. When big oil is leaning in, you know this thing has legs.

PUE Impact

Traditional air-cooled datacenter facilities heavily rely on HVAC systems to manage the heat generated by servers. These systems involve large air-conditioners that regulate temperature and humidity, with the air being circulated throughout the data halls to maintain optimal conditions. However, this approach is far from energy-efficient, leading to average PUE values of around 1.4-1.5 globally, even though exceptional cases like Google have achieved a commendable PUE of 1.1.

By adopting immersion cooling and eliminating the need for fans and complex HVAC systems, datacenter operators can achieve significantly lower PUE levels of around 1.03-1.05.

For those in the back, that's Non-IT Equipment using 3-5%, instead of 40-50%!

As less equipment is needed to run the servers (fans) and to cool them (HVAC and supporting infrastructure), there is a reduction of materials required to produce and run data centers, further decreasing environmental waste.

Since servers are submerged in a dielectric fluid, it's the fluid that absorbs the heat. This fluid is then cooled using a heat exchanger, which transfers the heat to water in a closed-loop system. Consequently, immersion cooling reduces the energy required for cooling and achieves remarkable efficiency gains compared to air-cooling - reflective in the PUE's above.

https://www.gigabyte.com/Article/two-phase-and-single-phase-liquid-immersion-cooling

Further, HVAC systems rely on harmful refrigerants for cooling, which if leaked, can be potent greenhouse gases. Using dielectric fluids, which can also be biodegradable, are not only more efficient, but are also significantly less harmful to the environment.

WUE Impact

In air-cooled facilities, the heat rejected by servers is dissipated through cooling towers, consuming a substantial amount of water. To put this into perspective, a 20-megawatt facility can consume up to 480,000 gallons of water per day, equivalent to 24 swimming pools. While calculating the average global WUE for data centers is challenging due to a lack of published data, estimates suggest that the median WUE is around 1.3 liters per kilowatt-hour (kWh). However, exceptions like Meta have reported an average WUE as low as 0.24 liters per kWh.

Lake Mead at critically low levels

In contrast, immersion cooling significantly reduces water consumption. The heat absorbed by the dielectric fluid can be efficiently dissipated using a heat exchanger, which often employs a closed-loop system. This method consumes substantially less water and can utilize non-potable water sources, thereby minimizing the strain on freshwater resources. Some immersion cooling solutions even support waterless deployments by leveraging adiabatic cooling towers.

Heat Reuse

One of the remarkable advantages of immersion-cooled datacenters is the ability to capture and reuse a substantial portion of the generated heat. In some cases, over 95% of the heat can be recaptured and repurposed, which is often unfeasible in air-cooled data centers. This captured heat can be directed to district heating systems, used for heating swimming pools, or, as demonstrated by Wyoming Hyperscale, employed in large greenhouses to cultivate fresh fruits and vegetables locally. Consequently, this reduces reliance on long-distance shipping and offers fresher produce to the region.

~900 miles and 2 days of transit for some CA grown strawberries

The prospect of reducing truck transportation of older and more expensive produce presents a significant win in terms of both environmental impact and economic efficiency.

One more thing?!

While not directly an environmental sustainability benefit, it's worth mentioning that immersion cooling can significantly reduce the noise pollution associated with large, air-cooled server farms. This can improve local quality of life of data center operators, and opens up many more possibilities of installations, without noise complaints from the neighbors.

Conclusion

In summary, immersion cooling provides a compelling solution for datacenter operators aiming to improve scalability, flexibility, and environmental sustainability. By adopting immersion cooling, datacenters can achieve exceptional energy efficiency with significantly reduced PUE values compared to air-cooled facilities. Water usage is also substantially decreased, and the ability to capture and repurpose heat opens up new opportunities for energy reuse. Immersion cooling truly offers the best of both worlds, enabling datacenters to balance power consumption, water usage, and the valuable heat created, ultimately fostering a more sustainable and efficient digital infrastructure.