Data Centres Shift to Dry Cooling Amid Growing Water Scarcity

With rising global temperatures and water scarcity becoming an ever-growing concern, data centers around the world are facing increasing pressure to adopt green cooling systems. The urgency is more so as artificial intelligence (AI) drives the rise in processing power, resulting in more heat density. Traditionally, most data centers utilized water-based cooling technologies to manage heat loads, but with increasing environmental pressures, the shift is towards dry cooling methods that do not rely on water.

Water has been highly prized for its much superior thermal conduction performance—approximately 3,500 times higher than air at atmospheric pressure. But traditional water-based systems are bound to be plagued by too much water loss in the form of high evaporation levels. This is especially unacceptable in locations where data centres are being constructed because energy costs are low and land is abundant but water supplies are scarce.

Current liquid cooling systems have two loops, the Technology Cooling System (TCS) and the Facility Water System (FWS). The TCS is a closed loop where water or refrigerants are utilized to cool computer equipment. Since the liquid in this loop is recirculated, there is no loss of water and no water use limitations are applied. But the FWS loop, removing heat from the plant, tends to utilize treated water and release heat in the form of evaporative cooling towers. These towers, for all the efficiency improvements, continue to lose vast quantities of water by evaporation—particularly in hot climates.

Evaporative cooling, as energy-efficient as it is, continues to be a favorite approach. Hot water cascades over surfaces in cooling towers and is cooled by evaporation. However, in dry and hot conditions, evaporation rates are higher, and hence water loss is more. Evaporative cooling use is now becoming illegal or even banned in water-conservation-based areas. Direct evaporative or adiabatic cooling, where water is sprayed to cool air quickly, has also been utilized in arid areas such as Arizona, but the rising numbers of heatwaves and deteriorating water deficiencies are making it increasingly unviable.

Dry cooling is increasingly a viable, environmentally friendly option. In contrast to water-based systems, dry cooling uses only air for heat removal from data centre conditions. Dry cooling systems consist of air-cooled heat exchangers and make no use of any type of evaporation and thus save water completely. But they consume more energy with respect to moving large quantities of air. Doubling fan speeds by the cube law doubles energy use eightfold, so dry cooling is more energy-efficient than water-based cooling. But where extreme water shortages are being encountered, the energy to water saving balance generally makes dry cooling systems acceptable.

As environmental laws become stricter and more awareness of the water-energy nexus is generated, even greater numbers of data centres will be compelled to use dry cooling technologies but with an added increase in energy consumption. Meanwhile, liquid cooling remains necessary for highly heat-producing AI workloads. Operators increasingly incorporate hybrid systems in order to balance efficiency and sustainability, employing closed-loop liquid cooling to support high-performance computing and dry cooling techniques to manage overall thermal loads without water wastage.

The increasing challenge for data centre managers is how they can manage to keep computing power, thermal load, and environmental footprint in check. The balancing act is particularly vital as data need increases worldwide with AI, cloud computing, and digital transformation.

As climate change reshapes the earlier presumptions on resource availability, attention to sustainable infrastructure will only rise. Cooling technology innovation will remain essential to ensuring that the digital economy continues to expand without adding to the pressure on the world's water supplies.

Source- TechTarget