As data centre requirements continue to expand to meet surging demand, traditional water intensive cooling methods are facing greater scrutiny due to their negative environmental impact.
Consequently, operators are turning to more innovative water-saving techniques that maintain thermal regulation without straining local water supplies. This shift not only cuts freshwater usage, but also bolsters resilience against droughts and future regulatory constraints.
What, then, are the alternatives?
One such innovation is free air economisation. Instead of running water-cooled chillers, economisers filter and circulate cool external air directly through the data hall when outdoor conditions permit. Modern systems auto-switch between free air and traditional mechanical cooling depending on the season, ensuring optimal performance year round.
This, ultimately, reduces water usage by up to 100% during cool seasons, lowers operational costs and minimises carbon emissions by relying on natural air flows.
Another option is rear door heat exchangers (RDHx). These attach to rack backs, capturing and rejecting heat via refrigerant coils rather than water coils. This approach eliminates larger, water-cooled chillers and avoids water consumption altogether.
Immersion cooling submerges server components in dielectric fluids (non-conductive liquids with high heat capacity) absorbing heat directly at the source. This displaces water-cooled chillers and air handlers, offering significant energy and water savings. This reduces water use to near zero and can improve energy efficiency by up to 40% compared to air cooling.
Beyond immersion cooling, two-phase liquid loops circulate specialised refrigerants. When the refrigerant boils, it carries large amounts of latent heat away, condenses in an external heat exchanger and repeats the cycle. These closed loops avoid evaporated water-cooling towers and drastically curtail water reliance.
Data centres can pair thermal storage tanks with cooling systems to shift peak loads and reduce water tower dependency. During off-peak hours, excess cooling capacity charges the storage medium. Meanwhile, waste heat harvested from servers finds new life heating office spaces or district heat networks by being a ‘good neighbour’ and further offsetting water-cooled boiler demands.
AI platforms analyse sensor data, such as temperature, humidity, equipment, and adjust cooling valves, fan speeds and economiser thresholds in real time. By predicting thermal stress and dynamically balancing workloads, AI systems eliminate unnecessary cooling cycles that often trigger water evaporation in traditional towers.
While each solution can reduce your water usage demand, not all of them will be applicable to all data centres.
For instance, with new-build data centres these solutions can be readily incorporated into the design. Strategies such as free cooling, RDHx, and immersion cooling are particularly well-suited for early-stage integration. However, approaches like thermal energy storage and waste heat export require more detailed consideration during site selection and planning, especially regarding space requirements and proximity to potential heat consumers.
There is also growing demand to improve the performance of existing data centres or adapt them to accommodate AI servers. Unlike new-build facilities, retrofitting existing data centres presents greater challenges. The primary constraints are typically available space within the facility, as well as the structural capacity of the floor plates. Technologies such as thermal energy storage, the use of nearby water bodies, and waste heat export are further limited by site-specific factors like geolocation and planning permissions. These limitations require careful evaluation to determine the feasibility of implementing modern cooling and energy-saving strategies.
So, as the data centre sector continues to grapple with sustainability targets and water scarcity, there are plenty of alternative cooling innovations to consider. The focus, now, will be on the speed in which the sector upgrades its traditional legacy facilities.
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