The Shift from Liquid to Dry Cooling in a Warming World
In a world where water scarcity is becoming a critical challenge, the demand for sustainable data center cooling systems has never been higher. As AI continues to drive computing power, and with it, higher heat densities, data centers must find ways to stay cool without adding to global water stress. Two primary technologies are now in focus: Liquid cooling and dry cooling.
The Water-Energy-Cooling Dilemma
Water is a highly efficient medium for transferring heat, about 3,500 times more effective than air under standard conditions. However, much of the water used in traditional cooling systems is lost to evaporation, raising concerns in water-scarce regions where mega-data centers are increasingly being located due to low energy costs and land availability. As climate change intensifies and heat waves become more frequent, the need for responsible cooling systems is crucial.
Understanding Liquid Cooling Systems
Liquid cooling systems are now essential for handling high AI workloads. These systems involve two separate loops: the Technology Cooling System (TCS) and the Facility Water System (FWS).
TCS Loop: This closed-loop system uses water or refrigerant to remove heat from computing equipment. It recirculates within the system and doesn't lose any liquid, making it exempt from water use restrictions.
FWS Loop: This external loop carries the heat away from the building and usually involves treated water. The concern here is that when heat is released to the atmosphere, especially via evaporative cooling towers, significant water loss occurs.
Read More: As AI Grows, Data Centres Face Soaring Energy Demand
Evaporative Cooling: Efficient but Costly in Water
Cooling towers are still the most energy-efficient method of removing heat. They work by cascading warm FWS water over surfaces, using airflow and evaporation to cool it. Though modern towers use less water than older models, evaporation losses remain high, especially on hot, dry days. This method is increasingly restricted or even banned in regions where water conservation is prioritized.
Another technique, direct evaporative (adiabatic) cooling, sprays water to cool air or liquid rapidly. It's efficient in dry climates and is used in data centers in areas like Phoenix, Arizona. But rising global temperatures and water scarcity have made even these locations unsuitable for water-intensive cooling methods.
Dry Cooling: The New Normal
With stricter regulations and heightened awareness around water usage, dry cooling systems are becoming more common, even for large data centers. These systems depend solely on air to transfer heat and eliminate water discharge entirely. They use outdoor air coolers and liquid coils without any evaporation.
However, dry cooling comes with its own trade-offs. Moving large volumes of air requires fan power, and according to the cube law, doubling fan speed increases energy consumption by eight times. As a result, dry cooling is less energy efficient compared to water-based methods, especially in hot climates. Still, in many water-stressed areas, the power vs. water trade-off makes dry cooling the more sustainable choice.
Also Read: The AI Energy Crunch: Bigger Models, Bigger Consequences
Striking the Balance
Data centers today face a difficult balancing act, managing heat loads, maintaining uptime, and reducing both water and energy consumption. While liquid cooling remains the best option for high-density AI computing, dry cooling offers a practical solution in regions where water scarcity is a pressing issue.
As the world adapts to shifting climate realities, innovation in cooling technology will be key to sustaining digital growth without compromising environmental responsibility.
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Source: TechTarget
